old and new 7 quality control tool
DESCRIPTION
report fileof old and new 7 quality control toolTRANSCRIPT
1 DEFINITION of Quality Control
A process through which a business seeks to ensure that product quality is maintained
or improved and manufacturing errors are reduced or eliminated Quality control
requires the business to create an environment in which both management and
employees strive for perfection This is done by training personnel
creating benchmarks for product quality and testing products to check for statistically
significant variations
A major aspect of quality control is the establishment of well-defined controls These
controls help standardize both production and reactions to quality issues Limiting
room for error by specifying which production activities are to be completed by which
personnel reduces the chance that employees will be involved in tasks for which they
do not have adequate training
2 Importance of quality control
Quality control is essential to building a successful business that delivers products that
meet or exceed customersrsquo expectations It also forms the basis of an efficient
business that minimizes waste and operates at high levels of productivity A quality
control system based on a recognized standard such as ISO 9001 published by the
International Organization for Standardization provides a strong foundation for
achieving a wide range of marketing and operational benefits
3 Competitiveness
The ability to offer customers quality products provides a strong competitive
advantage Quality helps you to win business from competitors who are not able to
match your standards and gives you the opportunity to charge premium prices for a
superior product It can also open new business opportunities in market sectors where
quality is critical
1
4 Customer Loyalty
Providing the market with quality products helps to increase customer satisfaction and
loyalty Satisfied customers have confidence that your products will continue to
provide reliable performance in the future and that increases the likelihood that they
will buy from you again Satisfied customers may also recommend your products to
other companies either directly or by providing testimonials that you can use in your
marketing communications
5 Reputation
Quality makes an important contribution to your companyrsquos reputation particularly
with the growth of social media Customers share their views on products and services
on product review sites and social media such as Face book Positive reviews and
comments can reinforce your own marketing efforts but quality problems can have a
damaging effect on your reputation if the word spreads A major quality issue such as
a product recall may also attract media attention causing further damage
6 Compliance
Compliance with recognized quality standards may be essential for doing business
with certain groups of customers If you are part of a supply chain for example the
lead manufacturer may impose consistent quality standards on all members of the
chain Some customers aim to reduce or eliminate the cost of inspecting incoming
components or materials by insisting that their suppliers implement the same quality
system If you operate in a regulated sector such as chemicals or food you may have
to comply with industry quality standards
7 Costs
2
Quality control can help to reduce your production and product support costs A
quality control system helps to lower levels of waste and rework cutting costs and
improving productivity and production efficiency Delivering quality products can
also reduce the number of returns you have to handle or the cost of repairing or
servicing products in the field
Benefits of Using Quality Control in Manufacturing
The most obvious beneficiary of quality control is the customer who receives a high-
quality product This in turn benefits the company by ensuring customer satisfaction
which leads to repeat business customer loyalty and spreading the word about the
quality of the companys product Therefore quality control in manufacturing pays off
for a company in both reputation and revenue
Companies with quality control procedures in place are far less likely to face product
recalls or safety hazards from poorly constructed products The cost associated with
these recalls can be steep In 2009 Toyota had to recall 124 million cars for sticky
gas pedals and floor mats that could jam accelerators at a cost of approximately $2
billion This could have been avoided had quality control been properly implemented
Methods of quality control
Old 7 tools
Paretochart
Fishbonediagram
Controlchart
Histogram
check sheet
Scatterdiagram
Stratification (flow chart or run chart)
3
4
Feature of this tools
DataorientationFocuson numericaldatameasure andcalculation
New 7 tools
Relationshipdiagram
Treediagram
Arrowdiagram
Affinitydiagram
Matrixdiagram
Matrixdataanalysis diagram
Processdecision programchart(PDPC)
Feature of new quality controls tools
Combineverbalwith numerical
Lookingforrootcause
Clarifyprioritizegoals andschedule
Involveeveryoneinto fullcooperation
Generateideas
5
Now starting with 1st quality control tools
1) Pareto chart or Pareto diagram
A Pareto chart is a bar graph The lengths of the bars represent frequency or cost (time
or money) and are arranged with longest bars on the left and the shortest to the right
In this way the chart visually depicts which situations are more significant
When to Use a Pareto Chart
When analyzing data about the frequency of problems or causes in a process
When there are many problems or causes and you want to focus on the most
significant
When analyzing broad causes by looking at their specific components
When communicating with others about your data
Pareto Chart Procedure
Decide what categories you will use to group items
Decide what measurement is appropriate Common measurements are
frequency quantity cost and time
Decide what period of time the Pareto chart will cover One work cycle One
full day A week
Collect the data recording the category each time (Or assemble data that
already exist)
Subtotal the measurements for each category
Determine the appropriate scale for the measurements you have collected The
maximum value will be the largest subtotal from step 5 (If you will do
optional steps 8 and 9 below the maximum value will be the sum of all
subtotals from step 5) Mark the scale on the left side of the chart
6
Construct and label bars for each category Place the tallest at the far left then
the next tallest to its right and so on If there are many categories with small
measurements they can be grouped as ldquootherrdquo
Steps 8 and 9 are optional but are useful for analysis and communication
Calculate the percentage for each category the subtotal for that category
divided by the total for all categories Draw a right vertical axis and label it
with percentages Be sure the two scales match For example the left
measurement that corresponds to one-half should be exactly opposite 50 on
the right scale
Calculate and draw cumulative sums Add the subtotals for the first and
second categories and place a dot above the second bar indicating that sum
To that sum add the subtotal for the third category and place a dot above the
third bar for that new sum Continue the process for all the bars Connect the
dots starting at the top of the first bar The last dot should reach 100 percent
on the right scale
Pareto Chart Examples
Example 1 shows how many customer complaints were received in each of five
categories
Example 2 takes the largest category ldquodocumentsrdquo from Example 1 breaks it
down into six categories of document-related complaints and shows cumulative
values
If all complaints cause equal distress to the customer working on eliminating
document-related complaints would have the most impact and of those working on
quality certificates should be most fruitful
7
8
2) The fishbone diagram
A Cause-and Effect Diagram also known as fish bone diagram is a tool that shows
systematic relationship between a result or a symptom or an effect and its possible
causes It is an effective tool to systematically generate ideas about causes for
problems and to present these in a structured form This tool was devised by Dr
Kouro Ishikawa and as mentioned earlier is also known as Ishikawa Diagram
Procedure
The steps in the procedure to prepare a cause-and-effect diagram are
1 Agree on the definition of the Effect for which causes are to be found Place the
effect in the dark box at the right Draw the spine or the backbone as a dark line
leading to the box for the effect
1 Determine the main groups or categories of causes Place them in boxes and
connect them through large bones to the backbone
2 Brainstorm to find possible causes and subsidiary causes under each of the main
groups Make sure that the route from the cause to the effect is correctly depicted The
path must start from a root cause and end in the effect
3 After completing all the main groups brainstorm for more causes that may have
escaped earlier
4 Once the diagram is complete discuss relative importance of the causes Short list
the important root causes
9
10
3) Check sheets
Also called defect concentration diagram A check sheet is a structured prepared
form for collecting and analyzing data This is a generic tool that can be adapted for a
wide variety of purposes
When to Use a Check Sheet
When data can be observed and collected repeatedly by the same person or at
the same location
When collecting data on the frequency or patterns of events problems
defects defect location defect causes etc
When collecting data from a production process
Check Sheet Procedure
Decide what event or problem will be observed Develop operational
definitions
Decide when data will be collected and for how long
Design the form Set it up so that data can be recorded simply by making
check marks or Xs or similar symbols and so that data do not have to be
recopied for analysis
Label all spaces on the form
Test the check sheet for a short trial period to be sure it collects the
appropriate data and is easy to use
Each time the targeted event or problem occurs record data on the check
sheet
Check Sheet Example
The figure below shows a check sheet used to collect data on telephone interruptions
The tick marks were added as data was collected over several weeks
11
12
4) Control chart
The control chart is a graph used to study how a process changes over time Data are
plotted in time order A control chart always has a central line for the average an
upper line for the upper control limit and a lower line for the lower control limit
These lines are determined from historical data By comparing current data to these
lines you can draw conclusions about whether the process variation is consistent (in
control) or is unpredictable (out of control affected by special causes of variation)
Control charts for variable data are used in pairs The top chart monitors the average
or the centring of the distribution of data from the process The bottom chart monitors
the range or the width of the distribution If your data were shots in target practice
the average is where the shots are clustering and the range is how tightly they are
clustered Control charts for attribute data are used singly
41 When to Use a Control Chart
When controlling ongoing processes by finding and correcting problems as they
occur
When predicting the expected range of outcomes from a process
When determining whether a process is stable (in statistical control)
When analyzing patterns of process variation from special causes (non-routine
events) or common causes (built into the process)
When determining whether your quality improvement project should aim to
prevent specific problems or to make fundamental changes to the process
Control Chart Basic Procedure
Choose the appropriate control chart for your data
Determine the appropriate time period for collecting and plotting data
13
Collect data construct your chart and analyze the data
Look for ldquoout-of-control signalsrdquo on the control chart When one is identified mark it
on the chart and investigate the cause Document how you investigated what you
learned the cause and how it was corrected
Out-of-control signals
A single point outside the control limits In Figure 1 point sixteen is above the UCL
(upper control limit)
Two out of three successive points are on the same side of the centreline and farther
than 2 σ from it In Figure 1 point 4 sends that signal
Four out of five successive points are on the same side of the centreline and farther
than 1 σ from it In Figure 1 point 11 sends that signal
A run of eight in a row are on the same side of the centreline Or 10 out of 11 12 out
of 14 or 16 out of 20 In Figure 1 point 21 is eighth in a row above the centreline
Obvious consistent or persistent patterns that suggest something unusual about your
data and your process
5 Continue to plot data as they are generated As each new data point is plotted
check for new out-of-control signals
14
6 When you start a new control chart the process may be out of control If so the
control limits calculated from the first 20 points are conditional limits When you
have at least 20 sequential points from a period when the process is operating in
control recalculate control limits
5) Histogram chart
A frequency distribution shows how often each different value in a set of data occurs
A histogram is the most commonly used graph to show frequency distributions It
looks very much like a bar chart but there are important differences between them
When to Use a Histogram
When the data are numerical
When you want to see the shape of the datarsquos distribution especially when
determining whether the output of a process is distributed approximately
normally
When analyzing whether a process can meet the customerrsquos requirements
When analyzing what the output from a supplierrsquos process looks like
When seeing whether a process change has occurred from one time period to
another
When determining whether the outputs of two or more processes are different
When you wish to communicate the distribution of data quickly and easily to
others
Histogram Construction
Collect at least 50 consecutive data points from a process
Use the histogram worksheet to set up the histogram It will help you determine the
number of bars the range of numbers that go into each bar and the labels for the bar
edges After calculating W in step 2 of the worksheet use your judgment to adjust it
to a convenient number For example you might decide to round 09 to an even 10
15
The value for W must not have more decimal places than the numbers you will be
graphing
Draw x- and y-axes on graph paper Mark and label the y-axis for counting data
values Mark and label the x-axis with the L values from the worksheet The spaces
between these numbers will be the bars of the histogram Do not allow for spaces
between bars
For each data point mark off one count above the appropriate bar with an X or by
shading that portion of the bar
Histogram Analysis
Before drawing any conclusions from your histogram satisfy yourself that the process
was operating normally during the time period being studied If any unusual events
affected the process during the time period of the histogram your analysis of the
histogram shape probably cannot be generalized to all time periods
Analyze the meaning of your histogramrsquo
16
17
6) Scatter chart
The scatter diagram graphs pairs of numerical data with one variable on each axis to
look for a relationship between them If the variables are correlated the points will
fall along a line or curve The better the correlation the tighter the points will hug the
line
When to Use a Scatter Diagram
When you have paired numerical data
When your dependent variable may have multiple values for each value of your
independent variable
When trying to determine whether the two variables are related such ashellip
When trying to identify potential root causes of problems
After brainstorming causes and effects using a fishbone diagram to determine
objectively whether a particular cause and effect are related
When determining whether two effects that appears to be related both occur with the
same cause
When testing for autocorrelation before constructing a control chart
Scatter Diagram Procedure
Collect pairs of data where a relationship is suspected
Draw a graph with the independent variable on the horizontal axis and the dependent
variable on the vertical axis For each pair of data put a dot or a symbol where the x-
axis value intersects the y-axis value (If two dots fall together put them side by side
touching so that you can see both)
18
Look at the pattern of points to see if a relationship is obvious If the data clearly form
a line or a curve you may stop The variables are correlated You may wish to use
regression or correlation analysis now Otherwise complete steps 4 through 7
Divide points on the graph into four quadrants If there are X points on the graph
Count X2 points from top to bottom and draw a horizontal line
Count X2 points from left to right and draw a vertical line
If number of points is odd draw the line through the middle point
Count the points in each quadrant Do not count points on a line
Add the diagonally opposite quadrants Find the smaller sum and the total of points in
all quadrants
A = points in upper left + points in lower right
B = points in upper right + points in lower left
Q = the smaller of A and B
N = A + B
Look up the limit for N on the trend test table
If Q is less than the limit the two variables are related
If Q is greater than or equal to the limit the pattern could have occurred from random
chance
19
Scatter Diagram Example
The ZZ-400 manufacturing team suspects a relationship between product purity
(percent purity) and the amount of iron (measured in parts per million or ppm) Purity
and iron are plotted against each other as a scatter diagram as shown in the figure
below
There are 24 data points Median lines are drawn so that 12 points fall on each side for
both percent purity and ppm iron
To test for a relationship they calculate
A = points in upper left + points in lower right = 9 + 9 = 18
B = points in upper right + points in lower left = 3 + 3 = 6
Q = the smaller of A and B = the smaller of 18 and 6 = 6
N = A + B = 18 + 6 = 24
20
Then they look up the limit for N on the trend test table For N = 24 the limit is 6
Q is equal to the limit Therefore the pattern could have occurred from random
chance and no relationship is demonstrated
Scatter Diagram Example
Scatter Diagram Considerations
Here are some examples of situations in which might you use a scatter diagram
Variable A is the temperature of a reaction after 15 minutes Variable B measures the
colour of the product You suspect higher temperature makes the product darker Plot
temperature and colour on a scatter diagram
Variable A is the number of employees trained on new software and variable B is the
number of calls to the computer helps line You suspect that more training reduces the
number of calls Plot number of people trained versus number of calls
To test for autocorrelation of a measurement being monitored on a control chart plot
this pair of variables Variable A is the measurement at a given time Variable B is the
same measurement but at the previous time If the scatter diagram shows correlation
do another diagram where variable B is the measurement two times previously Keep
increasing the separation between the two times until the scatter diagram shows no
correlation
21
Even if the scatter diagram shows a relationship do not assume that one variable
caused the other Both may be influenced by a third variable
When the data are plotted the more the diagram resembles a straight line the stronger
the relationship
If a line is not clear statistics (N and Q) determine whether there is reasonable
certainty that a relationship exists If the statistics say that no relationship exists the
pattern could have occurred by random chance
If the scatter diagram shows no relationship between the variables consider whether
the data might be stratified
If the diagram shows no relationship consider whether the independent (x-axis)
variable has been varied widely Sometimes a relationship is not apparent because the
data donrsquot cover a wide enough range
Think creatively about how to use scatter diagrams to discover a root cause
Drawing a scatter diagram is the first step in looking for a relationship between
variables
22
7) Stratification
Stratification is a technique used in combination with other data analysis tools When
data from a variety of sources or categories have been lumped together the meaning
of the data can be impossible to see This technique separates the data so that patterns
can be seen
When to Use Stratification
Before collecting data
When data come from several sources or conditions such as shifts days of the
week suppliers or population groups
When data analysis may require separating different sources or conditions
Stratification Procedure
Before collecting data consider which information about the sources of the data
might have an effect on the results Set up the data collection so that you collect that
information as well
When plotting or graphing the collected data on a scatter diagram control chart
histogram or other analysis tool use different marks or colours to distinguish data
from various sources Data that are distinguished in this way are said to be
ldquostratifiedrdquo
Analyze the subsets of stratified data separately For example on a scatter diagram
where data are stratified into data from source 1 and data from source 2 draw
quadrants count points and determine the critical value only for the data from source
1 then only for the data from source 2
Stratification Example
23
The ZZndash400 manufacturing team drew a scatter diagram to test whether product
purity and iron contamination were related but the plot did not demonstrate a
relationship Then a team member realized that the data came from three different
reactors The team member redrew the diagram using a different symbol for each
reactorrsquos data
Now patterns can be seen The data from reactor 2 and reactor 3 are circled Even
without doing any calculations it is clear that for those two reactors purity decreases
as iron increases However the data from reactor 1 the solid dots that are not circled
do not show that relationship Something is different about reactor 1
Stratification Considerations
Here are examples of different sources that might require data to be stratified
Equipment
Shifts
Departments
24
Materials
Suppliers
Day of the week
Time of day
Products
Survey data usually benefit from stratification
Always consider before collecting data whether stratification might be needed during
analysis Plan to collect stratification information After the data are collected it might
be too late
On your graph or chart include a legend that identifies the marks or colours used
25
Now starting with new 7 quality control tool
Need of new quality control tool
Many customer requirements cannot always be adequately expressed by numerical
data alone Nevertheless even verbal statements can be expressions of facts because
it represents facts we ought to use Verbal data as well as numerical data in
controlling the managing quality It provides both quality control as well as
improvement during the manufacturing process
Benefits of new 7 quality control tool
Combine verbal with Numerical data
Looking for root cause
Clarify prioritize goals and schedule
Involve everyone into full cooperation and generate new ideas 1048577
The first new quality control tool is
1) Affinity Diagram
Application
An affinity diagram is used to organize into groupings large number of ideas opinions
or concerns about a Particular topic
Description
When a large number of ideas opinions or other concerns about a particular topic are
being collected this tool organizes the information into grouping~~based on the
natural relationships that exist among them The process is designed to stimulate
creativity and full participation It works best in groups of limited Size (a maximum
26
of eight members is recommended) in which members are accustomed to working
together This tool is often used to organize ideas generated by brainstorming
Procedure
State the topic to be studied in broad terms(details may prejudice the
response)
Record as many individual ideas opinions or concerns as possible on cards
(one per
card)
Mix the cards and spread them randomly on a large table
Group related cards together as follows
a)sort cards that seem to be related into groups and
b) limit number of grouping to ten without forcing single cards into groups
Locate or create a header card that captures the meaning of each group
Place this header card on top
Transfer the information from cards onto paper organized by groupings
Example For next generation digital camera we can organize the customer
Complains and requirements in an Affinity Diagram1048577
27
Affinity diagram
28
2) Tree diagram
Application
A tree diagram is used to show the interrelation between a topic and its component
elements
Description
A tree diagram systematically breaks down a topic into its component elements Ideas
generated by
Brainstorming and graphed or clustered with an affinity diagram can be converted
into a tree diagram
to show logical and sequential links This tool can be used in planning and problem
solving
Procedure
State the topic to be studied clearly
Define the major categories of the topic(brainstorm or use the header cards
from the affinity diagram)
Construct the diagram by placing the topic in a box on the left-hand side
Branch the major categories laterally to the right
For each major category define the component elements and sub-elements if
any
Laterally branch to the right the component elements and sub-elements for
each major category and
Review the diagram to ensure that there are no gaps in either sequence or
logic
29
30
3) Arrow diagram
Purpose To create a visual presentation of the steps of a process or tasks necessary to
complete a project with special emphasis on the time taken for these activities
Procedure
1 List all the tasks or activities needed to be accomplished before the process of the
project
2 Decide which steps are undertaken in series and which steps can be run in parallel
Arrange the
Activities in a proper sequence
3 Prepare lsquoEvent Nodesrsquo at the completion of steps and number them
4 Write the description of the step and decide the time required for completing each
step
5 Calculate the earliest time to reach an event node for the start of the process
7 Ager the time for all event nodes including the completion of the process or the
project is available one calculates the latest time by which an event node must be
reached
Application
The diagram is also useful in planning and scheduling steps in complicated processes
especially in planning and scheduling projects which involve a large number of
activities
Example
31
1 Identify the tasks Eg 123hellip15
2 Know the time each task needs
3 Determine which tasks can be run in parallel and in normal sequences
4 Draw the sequence diagram and find the critical path
5 Calculate the project duration
6 Calculate the earliest starting time (or the earliest finishing time of last task) and the
latest finishing time
of each task(the latest starting time for the following task)
7 Mark the time indication
32
33
4) Process Decision Program Chart (PDPC)
Def The process decision program chart (PDPC) method helps us select the best
processes to obtain optimum results by evaluating the progress of events and various
conceivable outcomes
Description
The process decision program chart (PDPC) method is used to define the solution
process when dealing with problems that have more than one possible outcome [t
anticipates the unexpected Outcomes at each stage and plans for it
PDPC has two following patterns
Pattern I ndash In this pattern process starts with initial condition lsquoArsquo and proceeds to the
desired final condition lsquoZrsquo in an organized manner
Pattern 11- In this pattern first the final conditionrsquosrsquo is set Then the process from lsquoZrsquo
to the initial point lsquoArsquo is developed with the inclusion of various alternatives from
many points of view
Procedure
Discuss the issues related to the project among a cross-functional team
Discuss which issues must be examined and identify those issues
Consider and note down all the anticipated results for the identified issues
Weigh the feasibility of each solution proposed and investigate alternate
solutions
Classify each issue according to its urgency number of operations required
likelihood of Occurrence and difficulty
Consider the anticipated results and alternative solutions related to issues that
must be addressed immediately and link the items with arrows to the desired
goal
34
Prioritize the different issues and consider them all together Information
related to one set of
Possibilities could influence another set Related items shall be linked with a
broken line
If the department that will handle a process involving several lines is
determined circle
the process and write the name of the department within
Set a target date for completion
Have regular meetings to check progress in terms of the original PDPC
35
36
37
38
5) Matrix diagram
Purpose1) Explore the existence and the extent of relations between individual items in 2 sets
of factors or features and characteristics and express them in a symbolic form that is
easy to understand
2) Mostly used to understand the relations between the customer expectations as
expressed by the customers and product characteristics as designed manufactured and
tested by the manufacturer
Procedures1 Determine 2 sets of factors for which the relations are needed to be established
2 Divide the features and characteristics into primary secondary and tertiary
characteristics
3 Place the features vertically on the leg side of the matrix and characteristics
horizontally on top of the matrix
4 Enter the importance of the features on the column ager that for the tertiary
features10485775 In the main body of the matrix use the symbols to represent the degree of
connections between the feature and characteristics
6 Choose and define relationship symbols Most commonly used symbols are as
given below
Strong relationship=
Relationship =
Likely relationship=
Application
bull Matrix diagram can be used to solve problems by arranging data in such a way that
the relations between relevant factors are brought into sharp focus
bull There is no limit to the use of the tool
39
bull The most important application of matrix diagram is in clarifying relations between
individual features of customer requirements and individual product characteristics
Example 1
Matrix Diagram for Quality Functions and Responsibilities
40
41
6) Matrix Data Analysis Diagram1048577
Purpose
To present numerical data about two sets of factors in a matrix form and
analyze it to get numerical output
Can be applied in understanding the products and products characteristics
Procedure1048577
1 Decide the two factors whose relations are to be analyzed
2 Check the number of individual items in the two factors
3 Prepare a matrix to accommodate all the items of the two factors
4 Enter numerical data in the matrix
5 Give the diagram a suitable title
Example
42
43
44
7) Relationship diagram
This diagram clarifies the interrelations in a complex situation involving many
interrelated factors and serves to clarify the cause and effect relationships among
factors
Description
Relations diagram is defined as a technique used to solve problems that have complex
cause and effect relationships among a number of problems and factors that influence
them
Format
A special feature of relation diagram is its unrestricted Format However general
formats are as given below
1) Centrally converging relations diagram
The major item or problem to be solved is located in the center and the related factors
are arranged around the item or problem in such a way as to indicate close
relationships
2) Directionally intensive relations diagram
The major item or problem to be solved is located on one side of the diagram and the
various factors arranged in accordance with the flow of their major cause-and-effect
relationships on the other side
3) Relationship indication relations diagram
There are no restrictions on this format because the main point is to arrange the cause-
and-effect Relationships of the application items or factors so that they are expressed
in a straightforward manner in a Diagram
45
Procedure
1) Define the issueproblem in such a way that it is clearly understood and agreed on
by team members
2) Assemble the cross-functional team
3) Layout all the ideasissue cards that have been brought from other tools
4) Look for causeinfluence relationships between all ideas and draw relationship
arrows
a) Choose any of the ideas as a starting point and work through them in sequence
b)An outgoing arrow from an idea indicates that it is the stronger cause or influence
c) Draw only one way relationship arrows in the direction of the stronger cause or
Influence Make a decision on the stronger direction Do not draw two headed arrows
5) Review and revise the relationsrsquo diagram
6) Tally the number of outgoing and incoming arrows and select key items for further
planning
-record and clearly mark next to each issue the number of arrows going in and out of
it
-find the items with the highest number outgoing arrows and the items with the
highest number of incoming arrows
-a high number of outgoing arrows indicate that the item is a root cause and should be
tackle first
46
-a high number of incoming arrows indicate that the item is a key outcome and may
become a focus for planning either as a meaningful measure of overall success or as a
redefinition of the original issue under discussion
Example
47
48
Conclusions
Statististical QC is chiefly concerned in making sure that several procedures
and working arrangements are in place to provide for effective and efficient
statistical processes to minimize the risk of errors or weaknesses in
procedures or systems or in source material
Seven QC tools are most helpful in troubleshooting issues related to quality
All processes are affected by multiple factors and therefore statistical QC tools
can be applied to any process
The continuous use of these tools upgrades the personnel characteristics of the
people involved It enhances their ability to think generate ideas solve
problem and do proper planning
49
References asqorglearn-about-qualityseven-basic-quality-toolsoverviewhtml
httpsenwikipediaorgwikiSeven_Basic_Tools_of_Quality
wwwijergsorgfilesdocumentsAPPLICATION-45pd
httpssrcalionsciencecompdfQualityToolspdf
www3haorghkqehwiserdoc7bqtpdf
wwwmathmunca~variyathNew7QCToolspd
50
- 1 DEFINITION of Quality Control
- 3 Competitiveness
- 4 Customer Loyalty
- 5 Reputation
- 6 Compliance
- 7 Costs
- Benefits of Using Quality Control in Manufacturing
-
4 Customer Loyalty
Providing the market with quality products helps to increase customer satisfaction and
loyalty Satisfied customers have confidence that your products will continue to
provide reliable performance in the future and that increases the likelihood that they
will buy from you again Satisfied customers may also recommend your products to
other companies either directly or by providing testimonials that you can use in your
marketing communications
5 Reputation
Quality makes an important contribution to your companyrsquos reputation particularly
with the growth of social media Customers share their views on products and services
on product review sites and social media such as Face book Positive reviews and
comments can reinforce your own marketing efforts but quality problems can have a
damaging effect on your reputation if the word spreads A major quality issue such as
a product recall may also attract media attention causing further damage
6 Compliance
Compliance with recognized quality standards may be essential for doing business
with certain groups of customers If you are part of a supply chain for example the
lead manufacturer may impose consistent quality standards on all members of the
chain Some customers aim to reduce or eliminate the cost of inspecting incoming
components or materials by insisting that their suppliers implement the same quality
system If you operate in a regulated sector such as chemicals or food you may have
to comply with industry quality standards
7 Costs
2
Quality control can help to reduce your production and product support costs A
quality control system helps to lower levels of waste and rework cutting costs and
improving productivity and production efficiency Delivering quality products can
also reduce the number of returns you have to handle or the cost of repairing or
servicing products in the field
Benefits of Using Quality Control in Manufacturing
The most obvious beneficiary of quality control is the customer who receives a high-
quality product This in turn benefits the company by ensuring customer satisfaction
which leads to repeat business customer loyalty and spreading the word about the
quality of the companys product Therefore quality control in manufacturing pays off
for a company in both reputation and revenue
Companies with quality control procedures in place are far less likely to face product
recalls or safety hazards from poorly constructed products The cost associated with
these recalls can be steep In 2009 Toyota had to recall 124 million cars for sticky
gas pedals and floor mats that could jam accelerators at a cost of approximately $2
billion This could have been avoided had quality control been properly implemented
Methods of quality control
Old 7 tools
Paretochart
Fishbonediagram
Controlchart
Histogram
check sheet
Scatterdiagram
Stratification (flow chart or run chart)
3
4
Feature of this tools
DataorientationFocuson numericaldatameasure andcalculation
New 7 tools
Relationshipdiagram
Treediagram
Arrowdiagram
Affinitydiagram
Matrixdiagram
Matrixdataanalysis diagram
Processdecision programchart(PDPC)
Feature of new quality controls tools
Combineverbalwith numerical
Lookingforrootcause
Clarifyprioritizegoals andschedule
Involveeveryoneinto fullcooperation
Generateideas
5
Now starting with 1st quality control tools
1) Pareto chart or Pareto diagram
A Pareto chart is a bar graph The lengths of the bars represent frequency or cost (time
or money) and are arranged with longest bars on the left and the shortest to the right
In this way the chart visually depicts which situations are more significant
When to Use a Pareto Chart
When analyzing data about the frequency of problems or causes in a process
When there are many problems or causes and you want to focus on the most
significant
When analyzing broad causes by looking at their specific components
When communicating with others about your data
Pareto Chart Procedure
Decide what categories you will use to group items
Decide what measurement is appropriate Common measurements are
frequency quantity cost and time
Decide what period of time the Pareto chart will cover One work cycle One
full day A week
Collect the data recording the category each time (Or assemble data that
already exist)
Subtotal the measurements for each category
Determine the appropriate scale for the measurements you have collected The
maximum value will be the largest subtotal from step 5 (If you will do
optional steps 8 and 9 below the maximum value will be the sum of all
subtotals from step 5) Mark the scale on the left side of the chart
6
Construct and label bars for each category Place the tallest at the far left then
the next tallest to its right and so on If there are many categories with small
measurements they can be grouped as ldquootherrdquo
Steps 8 and 9 are optional but are useful for analysis and communication
Calculate the percentage for each category the subtotal for that category
divided by the total for all categories Draw a right vertical axis and label it
with percentages Be sure the two scales match For example the left
measurement that corresponds to one-half should be exactly opposite 50 on
the right scale
Calculate and draw cumulative sums Add the subtotals for the first and
second categories and place a dot above the second bar indicating that sum
To that sum add the subtotal for the third category and place a dot above the
third bar for that new sum Continue the process for all the bars Connect the
dots starting at the top of the first bar The last dot should reach 100 percent
on the right scale
Pareto Chart Examples
Example 1 shows how many customer complaints were received in each of five
categories
Example 2 takes the largest category ldquodocumentsrdquo from Example 1 breaks it
down into six categories of document-related complaints and shows cumulative
values
If all complaints cause equal distress to the customer working on eliminating
document-related complaints would have the most impact and of those working on
quality certificates should be most fruitful
7
8
2) The fishbone diagram
A Cause-and Effect Diagram also known as fish bone diagram is a tool that shows
systematic relationship between a result or a symptom or an effect and its possible
causes It is an effective tool to systematically generate ideas about causes for
problems and to present these in a structured form This tool was devised by Dr
Kouro Ishikawa and as mentioned earlier is also known as Ishikawa Diagram
Procedure
The steps in the procedure to prepare a cause-and-effect diagram are
1 Agree on the definition of the Effect for which causes are to be found Place the
effect in the dark box at the right Draw the spine or the backbone as a dark line
leading to the box for the effect
1 Determine the main groups or categories of causes Place them in boxes and
connect them through large bones to the backbone
2 Brainstorm to find possible causes and subsidiary causes under each of the main
groups Make sure that the route from the cause to the effect is correctly depicted The
path must start from a root cause and end in the effect
3 After completing all the main groups brainstorm for more causes that may have
escaped earlier
4 Once the diagram is complete discuss relative importance of the causes Short list
the important root causes
9
10
3) Check sheets
Also called defect concentration diagram A check sheet is a structured prepared
form for collecting and analyzing data This is a generic tool that can be adapted for a
wide variety of purposes
When to Use a Check Sheet
When data can be observed and collected repeatedly by the same person or at
the same location
When collecting data on the frequency or patterns of events problems
defects defect location defect causes etc
When collecting data from a production process
Check Sheet Procedure
Decide what event or problem will be observed Develop operational
definitions
Decide when data will be collected and for how long
Design the form Set it up so that data can be recorded simply by making
check marks or Xs or similar symbols and so that data do not have to be
recopied for analysis
Label all spaces on the form
Test the check sheet for a short trial period to be sure it collects the
appropriate data and is easy to use
Each time the targeted event or problem occurs record data on the check
sheet
Check Sheet Example
The figure below shows a check sheet used to collect data on telephone interruptions
The tick marks were added as data was collected over several weeks
11
12
4) Control chart
The control chart is a graph used to study how a process changes over time Data are
plotted in time order A control chart always has a central line for the average an
upper line for the upper control limit and a lower line for the lower control limit
These lines are determined from historical data By comparing current data to these
lines you can draw conclusions about whether the process variation is consistent (in
control) or is unpredictable (out of control affected by special causes of variation)
Control charts for variable data are used in pairs The top chart monitors the average
or the centring of the distribution of data from the process The bottom chart monitors
the range or the width of the distribution If your data were shots in target practice
the average is where the shots are clustering and the range is how tightly they are
clustered Control charts for attribute data are used singly
41 When to Use a Control Chart
When controlling ongoing processes by finding and correcting problems as they
occur
When predicting the expected range of outcomes from a process
When determining whether a process is stable (in statistical control)
When analyzing patterns of process variation from special causes (non-routine
events) or common causes (built into the process)
When determining whether your quality improvement project should aim to
prevent specific problems or to make fundamental changes to the process
Control Chart Basic Procedure
Choose the appropriate control chart for your data
Determine the appropriate time period for collecting and plotting data
13
Collect data construct your chart and analyze the data
Look for ldquoout-of-control signalsrdquo on the control chart When one is identified mark it
on the chart and investigate the cause Document how you investigated what you
learned the cause and how it was corrected
Out-of-control signals
A single point outside the control limits In Figure 1 point sixteen is above the UCL
(upper control limit)
Two out of three successive points are on the same side of the centreline and farther
than 2 σ from it In Figure 1 point 4 sends that signal
Four out of five successive points are on the same side of the centreline and farther
than 1 σ from it In Figure 1 point 11 sends that signal
A run of eight in a row are on the same side of the centreline Or 10 out of 11 12 out
of 14 or 16 out of 20 In Figure 1 point 21 is eighth in a row above the centreline
Obvious consistent or persistent patterns that suggest something unusual about your
data and your process
5 Continue to plot data as they are generated As each new data point is plotted
check for new out-of-control signals
14
6 When you start a new control chart the process may be out of control If so the
control limits calculated from the first 20 points are conditional limits When you
have at least 20 sequential points from a period when the process is operating in
control recalculate control limits
5) Histogram chart
A frequency distribution shows how often each different value in a set of data occurs
A histogram is the most commonly used graph to show frequency distributions It
looks very much like a bar chart but there are important differences between them
When to Use a Histogram
When the data are numerical
When you want to see the shape of the datarsquos distribution especially when
determining whether the output of a process is distributed approximately
normally
When analyzing whether a process can meet the customerrsquos requirements
When analyzing what the output from a supplierrsquos process looks like
When seeing whether a process change has occurred from one time period to
another
When determining whether the outputs of two or more processes are different
When you wish to communicate the distribution of data quickly and easily to
others
Histogram Construction
Collect at least 50 consecutive data points from a process
Use the histogram worksheet to set up the histogram It will help you determine the
number of bars the range of numbers that go into each bar and the labels for the bar
edges After calculating W in step 2 of the worksheet use your judgment to adjust it
to a convenient number For example you might decide to round 09 to an even 10
15
The value for W must not have more decimal places than the numbers you will be
graphing
Draw x- and y-axes on graph paper Mark and label the y-axis for counting data
values Mark and label the x-axis with the L values from the worksheet The spaces
between these numbers will be the bars of the histogram Do not allow for spaces
between bars
For each data point mark off one count above the appropriate bar with an X or by
shading that portion of the bar
Histogram Analysis
Before drawing any conclusions from your histogram satisfy yourself that the process
was operating normally during the time period being studied If any unusual events
affected the process during the time period of the histogram your analysis of the
histogram shape probably cannot be generalized to all time periods
Analyze the meaning of your histogramrsquo
16
17
6) Scatter chart
The scatter diagram graphs pairs of numerical data with one variable on each axis to
look for a relationship between them If the variables are correlated the points will
fall along a line or curve The better the correlation the tighter the points will hug the
line
When to Use a Scatter Diagram
When you have paired numerical data
When your dependent variable may have multiple values for each value of your
independent variable
When trying to determine whether the two variables are related such ashellip
When trying to identify potential root causes of problems
After brainstorming causes and effects using a fishbone diagram to determine
objectively whether a particular cause and effect are related
When determining whether two effects that appears to be related both occur with the
same cause
When testing for autocorrelation before constructing a control chart
Scatter Diagram Procedure
Collect pairs of data where a relationship is suspected
Draw a graph with the independent variable on the horizontal axis and the dependent
variable on the vertical axis For each pair of data put a dot or a symbol where the x-
axis value intersects the y-axis value (If two dots fall together put them side by side
touching so that you can see both)
18
Look at the pattern of points to see if a relationship is obvious If the data clearly form
a line or a curve you may stop The variables are correlated You may wish to use
regression or correlation analysis now Otherwise complete steps 4 through 7
Divide points on the graph into four quadrants If there are X points on the graph
Count X2 points from top to bottom and draw a horizontal line
Count X2 points from left to right and draw a vertical line
If number of points is odd draw the line through the middle point
Count the points in each quadrant Do not count points on a line
Add the diagonally opposite quadrants Find the smaller sum and the total of points in
all quadrants
A = points in upper left + points in lower right
B = points in upper right + points in lower left
Q = the smaller of A and B
N = A + B
Look up the limit for N on the trend test table
If Q is less than the limit the two variables are related
If Q is greater than or equal to the limit the pattern could have occurred from random
chance
19
Scatter Diagram Example
The ZZ-400 manufacturing team suspects a relationship between product purity
(percent purity) and the amount of iron (measured in parts per million or ppm) Purity
and iron are plotted against each other as a scatter diagram as shown in the figure
below
There are 24 data points Median lines are drawn so that 12 points fall on each side for
both percent purity and ppm iron
To test for a relationship they calculate
A = points in upper left + points in lower right = 9 + 9 = 18
B = points in upper right + points in lower left = 3 + 3 = 6
Q = the smaller of A and B = the smaller of 18 and 6 = 6
N = A + B = 18 + 6 = 24
20
Then they look up the limit for N on the trend test table For N = 24 the limit is 6
Q is equal to the limit Therefore the pattern could have occurred from random
chance and no relationship is demonstrated
Scatter Diagram Example
Scatter Diagram Considerations
Here are some examples of situations in which might you use a scatter diagram
Variable A is the temperature of a reaction after 15 minutes Variable B measures the
colour of the product You suspect higher temperature makes the product darker Plot
temperature and colour on a scatter diagram
Variable A is the number of employees trained on new software and variable B is the
number of calls to the computer helps line You suspect that more training reduces the
number of calls Plot number of people trained versus number of calls
To test for autocorrelation of a measurement being monitored on a control chart plot
this pair of variables Variable A is the measurement at a given time Variable B is the
same measurement but at the previous time If the scatter diagram shows correlation
do another diagram where variable B is the measurement two times previously Keep
increasing the separation between the two times until the scatter diagram shows no
correlation
21
Even if the scatter diagram shows a relationship do not assume that one variable
caused the other Both may be influenced by a third variable
When the data are plotted the more the diagram resembles a straight line the stronger
the relationship
If a line is not clear statistics (N and Q) determine whether there is reasonable
certainty that a relationship exists If the statistics say that no relationship exists the
pattern could have occurred by random chance
If the scatter diagram shows no relationship between the variables consider whether
the data might be stratified
If the diagram shows no relationship consider whether the independent (x-axis)
variable has been varied widely Sometimes a relationship is not apparent because the
data donrsquot cover a wide enough range
Think creatively about how to use scatter diagrams to discover a root cause
Drawing a scatter diagram is the first step in looking for a relationship between
variables
22
7) Stratification
Stratification is a technique used in combination with other data analysis tools When
data from a variety of sources or categories have been lumped together the meaning
of the data can be impossible to see This technique separates the data so that patterns
can be seen
When to Use Stratification
Before collecting data
When data come from several sources or conditions such as shifts days of the
week suppliers or population groups
When data analysis may require separating different sources or conditions
Stratification Procedure
Before collecting data consider which information about the sources of the data
might have an effect on the results Set up the data collection so that you collect that
information as well
When plotting or graphing the collected data on a scatter diagram control chart
histogram or other analysis tool use different marks or colours to distinguish data
from various sources Data that are distinguished in this way are said to be
ldquostratifiedrdquo
Analyze the subsets of stratified data separately For example on a scatter diagram
where data are stratified into data from source 1 and data from source 2 draw
quadrants count points and determine the critical value only for the data from source
1 then only for the data from source 2
Stratification Example
23
The ZZndash400 manufacturing team drew a scatter diagram to test whether product
purity and iron contamination were related but the plot did not demonstrate a
relationship Then a team member realized that the data came from three different
reactors The team member redrew the diagram using a different symbol for each
reactorrsquos data
Now patterns can be seen The data from reactor 2 and reactor 3 are circled Even
without doing any calculations it is clear that for those two reactors purity decreases
as iron increases However the data from reactor 1 the solid dots that are not circled
do not show that relationship Something is different about reactor 1
Stratification Considerations
Here are examples of different sources that might require data to be stratified
Equipment
Shifts
Departments
24
Materials
Suppliers
Day of the week
Time of day
Products
Survey data usually benefit from stratification
Always consider before collecting data whether stratification might be needed during
analysis Plan to collect stratification information After the data are collected it might
be too late
On your graph or chart include a legend that identifies the marks or colours used
25
Now starting with new 7 quality control tool
Need of new quality control tool
Many customer requirements cannot always be adequately expressed by numerical
data alone Nevertheless even verbal statements can be expressions of facts because
it represents facts we ought to use Verbal data as well as numerical data in
controlling the managing quality It provides both quality control as well as
improvement during the manufacturing process
Benefits of new 7 quality control tool
Combine verbal with Numerical data
Looking for root cause
Clarify prioritize goals and schedule
Involve everyone into full cooperation and generate new ideas 1048577
The first new quality control tool is
1) Affinity Diagram
Application
An affinity diagram is used to organize into groupings large number of ideas opinions
or concerns about a Particular topic
Description
When a large number of ideas opinions or other concerns about a particular topic are
being collected this tool organizes the information into grouping~~based on the
natural relationships that exist among them The process is designed to stimulate
creativity and full participation It works best in groups of limited Size (a maximum
26
of eight members is recommended) in which members are accustomed to working
together This tool is often used to organize ideas generated by brainstorming
Procedure
State the topic to be studied in broad terms(details may prejudice the
response)
Record as many individual ideas opinions or concerns as possible on cards
(one per
card)
Mix the cards and spread them randomly on a large table
Group related cards together as follows
a)sort cards that seem to be related into groups and
b) limit number of grouping to ten without forcing single cards into groups
Locate or create a header card that captures the meaning of each group
Place this header card on top
Transfer the information from cards onto paper organized by groupings
Example For next generation digital camera we can organize the customer
Complains and requirements in an Affinity Diagram1048577
27
Affinity diagram
28
2) Tree diagram
Application
A tree diagram is used to show the interrelation between a topic and its component
elements
Description
A tree diagram systematically breaks down a topic into its component elements Ideas
generated by
Brainstorming and graphed or clustered with an affinity diagram can be converted
into a tree diagram
to show logical and sequential links This tool can be used in planning and problem
solving
Procedure
State the topic to be studied clearly
Define the major categories of the topic(brainstorm or use the header cards
from the affinity diagram)
Construct the diagram by placing the topic in a box on the left-hand side
Branch the major categories laterally to the right
For each major category define the component elements and sub-elements if
any
Laterally branch to the right the component elements and sub-elements for
each major category and
Review the diagram to ensure that there are no gaps in either sequence or
logic
29
30
3) Arrow diagram
Purpose To create a visual presentation of the steps of a process or tasks necessary to
complete a project with special emphasis on the time taken for these activities
Procedure
1 List all the tasks or activities needed to be accomplished before the process of the
project
2 Decide which steps are undertaken in series and which steps can be run in parallel
Arrange the
Activities in a proper sequence
3 Prepare lsquoEvent Nodesrsquo at the completion of steps and number them
4 Write the description of the step and decide the time required for completing each
step
5 Calculate the earliest time to reach an event node for the start of the process
7 Ager the time for all event nodes including the completion of the process or the
project is available one calculates the latest time by which an event node must be
reached
Application
The diagram is also useful in planning and scheduling steps in complicated processes
especially in planning and scheduling projects which involve a large number of
activities
Example
31
1 Identify the tasks Eg 123hellip15
2 Know the time each task needs
3 Determine which tasks can be run in parallel and in normal sequences
4 Draw the sequence diagram and find the critical path
5 Calculate the project duration
6 Calculate the earliest starting time (or the earliest finishing time of last task) and the
latest finishing time
of each task(the latest starting time for the following task)
7 Mark the time indication
32
33
4) Process Decision Program Chart (PDPC)
Def The process decision program chart (PDPC) method helps us select the best
processes to obtain optimum results by evaluating the progress of events and various
conceivable outcomes
Description
The process decision program chart (PDPC) method is used to define the solution
process when dealing with problems that have more than one possible outcome [t
anticipates the unexpected Outcomes at each stage and plans for it
PDPC has two following patterns
Pattern I ndash In this pattern process starts with initial condition lsquoArsquo and proceeds to the
desired final condition lsquoZrsquo in an organized manner
Pattern 11- In this pattern first the final conditionrsquosrsquo is set Then the process from lsquoZrsquo
to the initial point lsquoArsquo is developed with the inclusion of various alternatives from
many points of view
Procedure
Discuss the issues related to the project among a cross-functional team
Discuss which issues must be examined and identify those issues
Consider and note down all the anticipated results for the identified issues
Weigh the feasibility of each solution proposed and investigate alternate
solutions
Classify each issue according to its urgency number of operations required
likelihood of Occurrence and difficulty
Consider the anticipated results and alternative solutions related to issues that
must be addressed immediately and link the items with arrows to the desired
goal
34
Prioritize the different issues and consider them all together Information
related to one set of
Possibilities could influence another set Related items shall be linked with a
broken line
If the department that will handle a process involving several lines is
determined circle
the process and write the name of the department within
Set a target date for completion
Have regular meetings to check progress in terms of the original PDPC
35
36
37
38
5) Matrix diagram
Purpose1) Explore the existence and the extent of relations between individual items in 2 sets
of factors or features and characteristics and express them in a symbolic form that is
easy to understand
2) Mostly used to understand the relations between the customer expectations as
expressed by the customers and product characteristics as designed manufactured and
tested by the manufacturer
Procedures1 Determine 2 sets of factors for which the relations are needed to be established
2 Divide the features and characteristics into primary secondary and tertiary
characteristics
3 Place the features vertically on the leg side of the matrix and characteristics
horizontally on top of the matrix
4 Enter the importance of the features on the column ager that for the tertiary
features10485775 In the main body of the matrix use the symbols to represent the degree of
connections between the feature and characteristics
6 Choose and define relationship symbols Most commonly used symbols are as
given below
Strong relationship=
Relationship =
Likely relationship=
Application
bull Matrix diagram can be used to solve problems by arranging data in such a way that
the relations between relevant factors are brought into sharp focus
bull There is no limit to the use of the tool
39
bull The most important application of matrix diagram is in clarifying relations between
individual features of customer requirements and individual product characteristics
Example 1
Matrix Diagram for Quality Functions and Responsibilities
40
41
6) Matrix Data Analysis Diagram1048577
Purpose
To present numerical data about two sets of factors in a matrix form and
analyze it to get numerical output
Can be applied in understanding the products and products characteristics
Procedure1048577
1 Decide the two factors whose relations are to be analyzed
2 Check the number of individual items in the two factors
3 Prepare a matrix to accommodate all the items of the two factors
4 Enter numerical data in the matrix
5 Give the diagram a suitable title
Example
42
43
44
7) Relationship diagram
This diagram clarifies the interrelations in a complex situation involving many
interrelated factors and serves to clarify the cause and effect relationships among
factors
Description
Relations diagram is defined as a technique used to solve problems that have complex
cause and effect relationships among a number of problems and factors that influence
them
Format
A special feature of relation diagram is its unrestricted Format However general
formats are as given below
1) Centrally converging relations diagram
The major item or problem to be solved is located in the center and the related factors
are arranged around the item or problem in such a way as to indicate close
relationships
2) Directionally intensive relations diagram
The major item or problem to be solved is located on one side of the diagram and the
various factors arranged in accordance with the flow of their major cause-and-effect
relationships on the other side
3) Relationship indication relations diagram
There are no restrictions on this format because the main point is to arrange the cause-
and-effect Relationships of the application items or factors so that they are expressed
in a straightforward manner in a Diagram
45
Procedure
1) Define the issueproblem in such a way that it is clearly understood and agreed on
by team members
2) Assemble the cross-functional team
3) Layout all the ideasissue cards that have been brought from other tools
4) Look for causeinfluence relationships between all ideas and draw relationship
arrows
a) Choose any of the ideas as a starting point and work through them in sequence
b)An outgoing arrow from an idea indicates that it is the stronger cause or influence
c) Draw only one way relationship arrows in the direction of the stronger cause or
Influence Make a decision on the stronger direction Do not draw two headed arrows
5) Review and revise the relationsrsquo diagram
6) Tally the number of outgoing and incoming arrows and select key items for further
planning
-record and clearly mark next to each issue the number of arrows going in and out of
it
-find the items with the highest number outgoing arrows and the items with the
highest number of incoming arrows
-a high number of outgoing arrows indicate that the item is a root cause and should be
tackle first
46
-a high number of incoming arrows indicate that the item is a key outcome and may
become a focus for planning either as a meaningful measure of overall success or as a
redefinition of the original issue under discussion
Example
47
48
Conclusions
Statististical QC is chiefly concerned in making sure that several procedures
and working arrangements are in place to provide for effective and efficient
statistical processes to minimize the risk of errors or weaknesses in
procedures or systems or in source material
Seven QC tools are most helpful in troubleshooting issues related to quality
All processes are affected by multiple factors and therefore statistical QC tools
can be applied to any process
The continuous use of these tools upgrades the personnel characteristics of the
people involved It enhances their ability to think generate ideas solve
problem and do proper planning
49
References asqorglearn-about-qualityseven-basic-quality-toolsoverviewhtml
httpsenwikipediaorgwikiSeven_Basic_Tools_of_Quality
wwwijergsorgfilesdocumentsAPPLICATION-45pd
httpssrcalionsciencecompdfQualityToolspdf
www3haorghkqehwiserdoc7bqtpdf
wwwmathmunca~variyathNew7QCToolspd
50
- 1 DEFINITION of Quality Control
- 3 Competitiveness
- 4 Customer Loyalty
- 5 Reputation
- 6 Compliance
- 7 Costs
- Benefits of Using Quality Control in Manufacturing
-
Quality control can help to reduce your production and product support costs A
quality control system helps to lower levels of waste and rework cutting costs and
improving productivity and production efficiency Delivering quality products can
also reduce the number of returns you have to handle or the cost of repairing or
servicing products in the field
Benefits of Using Quality Control in Manufacturing
The most obvious beneficiary of quality control is the customer who receives a high-
quality product This in turn benefits the company by ensuring customer satisfaction
which leads to repeat business customer loyalty and spreading the word about the
quality of the companys product Therefore quality control in manufacturing pays off
for a company in both reputation and revenue
Companies with quality control procedures in place are far less likely to face product
recalls or safety hazards from poorly constructed products The cost associated with
these recalls can be steep In 2009 Toyota had to recall 124 million cars for sticky
gas pedals and floor mats that could jam accelerators at a cost of approximately $2
billion This could have been avoided had quality control been properly implemented
Methods of quality control
Old 7 tools
Paretochart
Fishbonediagram
Controlchart
Histogram
check sheet
Scatterdiagram
Stratification (flow chart or run chart)
3
4
Feature of this tools
DataorientationFocuson numericaldatameasure andcalculation
New 7 tools
Relationshipdiagram
Treediagram
Arrowdiagram
Affinitydiagram
Matrixdiagram
Matrixdataanalysis diagram
Processdecision programchart(PDPC)
Feature of new quality controls tools
Combineverbalwith numerical
Lookingforrootcause
Clarifyprioritizegoals andschedule
Involveeveryoneinto fullcooperation
Generateideas
5
Now starting with 1st quality control tools
1) Pareto chart or Pareto diagram
A Pareto chart is a bar graph The lengths of the bars represent frequency or cost (time
or money) and are arranged with longest bars on the left and the shortest to the right
In this way the chart visually depicts which situations are more significant
When to Use a Pareto Chart
When analyzing data about the frequency of problems or causes in a process
When there are many problems or causes and you want to focus on the most
significant
When analyzing broad causes by looking at their specific components
When communicating with others about your data
Pareto Chart Procedure
Decide what categories you will use to group items
Decide what measurement is appropriate Common measurements are
frequency quantity cost and time
Decide what period of time the Pareto chart will cover One work cycle One
full day A week
Collect the data recording the category each time (Or assemble data that
already exist)
Subtotal the measurements for each category
Determine the appropriate scale for the measurements you have collected The
maximum value will be the largest subtotal from step 5 (If you will do
optional steps 8 and 9 below the maximum value will be the sum of all
subtotals from step 5) Mark the scale on the left side of the chart
6
Construct and label bars for each category Place the tallest at the far left then
the next tallest to its right and so on If there are many categories with small
measurements they can be grouped as ldquootherrdquo
Steps 8 and 9 are optional but are useful for analysis and communication
Calculate the percentage for each category the subtotal for that category
divided by the total for all categories Draw a right vertical axis and label it
with percentages Be sure the two scales match For example the left
measurement that corresponds to one-half should be exactly opposite 50 on
the right scale
Calculate and draw cumulative sums Add the subtotals for the first and
second categories and place a dot above the second bar indicating that sum
To that sum add the subtotal for the third category and place a dot above the
third bar for that new sum Continue the process for all the bars Connect the
dots starting at the top of the first bar The last dot should reach 100 percent
on the right scale
Pareto Chart Examples
Example 1 shows how many customer complaints were received in each of five
categories
Example 2 takes the largest category ldquodocumentsrdquo from Example 1 breaks it
down into six categories of document-related complaints and shows cumulative
values
If all complaints cause equal distress to the customer working on eliminating
document-related complaints would have the most impact and of those working on
quality certificates should be most fruitful
7
8
2) The fishbone diagram
A Cause-and Effect Diagram also known as fish bone diagram is a tool that shows
systematic relationship between a result or a symptom or an effect and its possible
causes It is an effective tool to systematically generate ideas about causes for
problems and to present these in a structured form This tool was devised by Dr
Kouro Ishikawa and as mentioned earlier is also known as Ishikawa Diagram
Procedure
The steps in the procedure to prepare a cause-and-effect diagram are
1 Agree on the definition of the Effect for which causes are to be found Place the
effect in the dark box at the right Draw the spine or the backbone as a dark line
leading to the box for the effect
1 Determine the main groups or categories of causes Place them in boxes and
connect them through large bones to the backbone
2 Brainstorm to find possible causes and subsidiary causes under each of the main
groups Make sure that the route from the cause to the effect is correctly depicted The
path must start from a root cause and end in the effect
3 After completing all the main groups brainstorm for more causes that may have
escaped earlier
4 Once the diagram is complete discuss relative importance of the causes Short list
the important root causes
9
10
3) Check sheets
Also called defect concentration diagram A check sheet is a structured prepared
form for collecting and analyzing data This is a generic tool that can be adapted for a
wide variety of purposes
When to Use a Check Sheet
When data can be observed and collected repeatedly by the same person or at
the same location
When collecting data on the frequency or patterns of events problems
defects defect location defect causes etc
When collecting data from a production process
Check Sheet Procedure
Decide what event or problem will be observed Develop operational
definitions
Decide when data will be collected and for how long
Design the form Set it up so that data can be recorded simply by making
check marks or Xs or similar symbols and so that data do not have to be
recopied for analysis
Label all spaces on the form
Test the check sheet for a short trial period to be sure it collects the
appropriate data and is easy to use
Each time the targeted event or problem occurs record data on the check
sheet
Check Sheet Example
The figure below shows a check sheet used to collect data on telephone interruptions
The tick marks were added as data was collected over several weeks
11
12
4) Control chart
The control chart is a graph used to study how a process changes over time Data are
plotted in time order A control chart always has a central line for the average an
upper line for the upper control limit and a lower line for the lower control limit
These lines are determined from historical data By comparing current data to these
lines you can draw conclusions about whether the process variation is consistent (in
control) or is unpredictable (out of control affected by special causes of variation)
Control charts for variable data are used in pairs The top chart monitors the average
or the centring of the distribution of data from the process The bottom chart monitors
the range or the width of the distribution If your data were shots in target practice
the average is where the shots are clustering and the range is how tightly they are
clustered Control charts for attribute data are used singly
41 When to Use a Control Chart
When controlling ongoing processes by finding and correcting problems as they
occur
When predicting the expected range of outcomes from a process
When determining whether a process is stable (in statistical control)
When analyzing patterns of process variation from special causes (non-routine
events) or common causes (built into the process)
When determining whether your quality improvement project should aim to
prevent specific problems or to make fundamental changes to the process
Control Chart Basic Procedure
Choose the appropriate control chart for your data
Determine the appropriate time period for collecting and plotting data
13
Collect data construct your chart and analyze the data
Look for ldquoout-of-control signalsrdquo on the control chart When one is identified mark it
on the chart and investigate the cause Document how you investigated what you
learned the cause and how it was corrected
Out-of-control signals
A single point outside the control limits In Figure 1 point sixteen is above the UCL
(upper control limit)
Two out of three successive points are on the same side of the centreline and farther
than 2 σ from it In Figure 1 point 4 sends that signal
Four out of five successive points are on the same side of the centreline and farther
than 1 σ from it In Figure 1 point 11 sends that signal
A run of eight in a row are on the same side of the centreline Or 10 out of 11 12 out
of 14 or 16 out of 20 In Figure 1 point 21 is eighth in a row above the centreline
Obvious consistent or persistent patterns that suggest something unusual about your
data and your process
5 Continue to plot data as they are generated As each new data point is plotted
check for new out-of-control signals
14
6 When you start a new control chart the process may be out of control If so the
control limits calculated from the first 20 points are conditional limits When you
have at least 20 sequential points from a period when the process is operating in
control recalculate control limits
5) Histogram chart
A frequency distribution shows how often each different value in a set of data occurs
A histogram is the most commonly used graph to show frequency distributions It
looks very much like a bar chart but there are important differences between them
When to Use a Histogram
When the data are numerical
When you want to see the shape of the datarsquos distribution especially when
determining whether the output of a process is distributed approximately
normally
When analyzing whether a process can meet the customerrsquos requirements
When analyzing what the output from a supplierrsquos process looks like
When seeing whether a process change has occurred from one time period to
another
When determining whether the outputs of two or more processes are different
When you wish to communicate the distribution of data quickly and easily to
others
Histogram Construction
Collect at least 50 consecutive data points from a process
Use the histogram worksheet to set up the histogram It will help you determine the
number of bars the range of numbers that go into each bar and the labels for the bar
edges After calculating W in step 2 of the worksheet use your judgment to adjust it
to a convenient number For example you might decide to round 09 to an even 10
15
The value for W must not have more decimal places than the numbers you will be
graphing
Draw x- and y-axes on graph paper Mark and label the y-axis for counting data
values Mark and label the x-axis with the L values from the worksheet The spaces
between these numbers will be the bars of the histogram Do not allow for spaces
between bars
For each data point mark off one count above the appropriate bar with an X or by
shading that portion of the bar
Histogram Analysis
Before drawing any conclusions from your histogram satisfy yourself that the process
was operating normally during the time period being studied If any unusual events
affected the process during the time period of the histogram your analysis of the
histogram shape probably cannot be generalized to all time periods
Analyze the meaning of your histogramrsquo
16
17
6) Scatter chart
The scatter diagram graphs pairs of numerical data with one variable on each axis to
look for a relationship between them If the variables are correlated the points will
fall along a line or curve The better the correlation the tighter the points will hug the
line
When to Use a Scatter Diagram
When you have paired numerical data
When your dependent variable may have multiple values for each value of your
independent variable
When trying to determine whether the two variables are related such ashellip
When trying to identify potential root causes of problems
After brainstorming causes and effects using a fishbone diagram to determine
objectively whether a particular cause and effect are related
When determining whether two effects that appears to be related both occur with the
same cause
When testing for autocorrelation before constructing a control chart
Scatter Diagram Procedure
Collect pairs of data where a relationship is suspected
Draw a graph with the independent variable on the horizontal axis and the dependent
variable on the vertical axis For each pair of data put a dot or a symbol where the x-
axis value intersects the y-axis value (If two dots fall together put them side by side
touching so that you can see both)
18
Look at the pattern of points to see if a relationship is obvious If the data clearly form
a line or a curve you may stop The variables are correlated You may wish to use
regression or correlation analysis now Otherwise complete steps 4 through 7
Divide points on the graph into four quadrants If there are X points on the graph
Count X2 points from top to bottom and draw a horizontal line
Count X2 points from left to right and draw a vertical line
If number of points is odd draw the line through the middle point
Count the points in each quadrant Do not count points on a line
Add the diagonally opposite quadrants Find the smaller sum and the total of points in
all quadrants
A = points in upper left + points in lower right
B = points in upper right + points in lower left
Q = the smaller of A and B
N = A + B
Look up the limit for N on the trend test table
If Q is less than the limit the two variables are related
If Q is greater than or equal to the limit the pattern could have occurred from random
chance
19
Scatter Diagram Example
The ZZ-400 manufacturing team suspects a relationship between product purity
(percent purity) and the amount of iron (measured in parts per million or ppm) Purity
and iron are plotted against each other as a scatter diagram as shown in the figure
below
There are 24 data points Median lines are drawn so that 12 points fall on each side for
both percent purity and ppm iron
To test for a relationship they calculate
A = points in upper left + points in lower right = 9 + 9 = 18
B = points in upper right + points in lower left = 3 + 3 = 6
Q = the smaller of A and B = the smaller of 18 and 6 = 6
N = A + B = 18 + 6 = 24
20
Then they look up the limit for N on the trend test table For N = 24 the limit is 6
Q is equal to the limit Therefore the pattern could have occurred from random
chance and no relationship is demonstrated
Scatter Diagram Example
Scatter Diagram Considerations
Here are some examples of situations in which might you use a scatter diagram
Variable A is the temperature of a reaction after 15 minutes Variable B measures the
colour of the product You suspect higher temperature makes the product darker Plot
temperature and colour on a scatter diagram
Variable A is the number of employees trained on new software and variable B is the
number of calls to the computer helps line You suspect that more training reduces the
number of calls Plot number of people trained versus number of calls
To test for autocorrelation of a measurement being monitored on a control chart plot
this pair of variables Variable A is the measurement at a given time Variable B is the
same measurement but at the previous time If the scatter diagram shows correlation
do another diagram where variable B is the measurement two times previously Keep
increasing the separation between the two times until the scatter diagram shows no
correlation
21
Even if the scatter diagram shows a relationship do not assume that one variable
caused the other Both may be influenced by a third variable
When the data are plotted the more the diagram resembles a straight line the stronger
the relationship
If a line is not clear statistics (N and Q) determine whether there is reasonable
certainty that a relationship exists If the statistics say that no relationship exists the
pattern could have occurred by random chance
If the scatter diagram shows no relationship between the variables consider whether
the data might be stratified
If the diagram shows no relationship consider whether the independent (x-axis)
variable has been varied widely Sometimes a relationship is not apparent because the
data donrsquot cover a wide enough range
Think creatively about how to use scatter diagrams to discover a root cause
Drawing a scatter diagram is the first step in looking for a relationship between
variables
22
7) Stratification
Stratification is a technique used in combination with other data analysis tools When
data from a variety of sources or categories have been lumped together the meaning
of the data can be impossible to see This technique separates the data so that patterns
can be seen
When to Use Stratification
Before collecting data
When data come from several sources or conditions such as shifts days of the
week suppliers or population groups
When data analysis may require separating different sources or conditions
Stratification Procedure
Before collecting data consider which information about the sources of the data
might have an effect on the results Set up the data collection so that you collect that
information as well
When plotting or graphing the collected data on a scatter diagram control chart
histogram or other analysis tool use different marks or colours to distinguish data
from various sources Data that are distinguished in this way are said to be
ldquostratifiedrdquo
Analyze the subsets of stratified data separately For example on a scatter diagram
where data are stratified into data from source 1 and data from source 2 draw
quadrants count points and determine the critical value only for the data from source
1 then only for the data from source 2
Stratification Example
23
The ZZndash400 manufacturing team drew a scatter diagram to test whether product
purity and iron contamination were related but the plot did not demonstrate a
relationship Then a team member realized that the data came from three different
reactors The team member redrew the diagram using a different symbol for each
reactorrsquos data
Now patterns can be seen The data from reactor 2 and reactor 3 are circled Even
without doing any calculations it is clear that for those two reactors purity decreases
as iron increases However the data from reactor 1 the solid dots that are not circled
do not show that relationship Something is different about reactor 1
Stratification Considerations
Here are examples of different sources that might require data to be stratified
Equipment
Shifts
Departments
24
Materials
Suppliers
Day of the week
Time of day
Products
Survey data usually benefit from stratification
Always consider before collecting data whether stratification might be needed during
analysis Plan to collect stratification information After the data are collected it might
be too late
On your graph or chart include a legend that identifies the marks or colours used
25
Now starting with new 7 quality control tool
Need of new quality control tool
Many customer requirements cannot always be adequately expressed by numerical
data alone Nevertheless even verbal statements can be expressions of facts because
it represents facts we ought to use Verbal data as well as numerical data in
controlling the managing quality It provides both quality control as well as
improvement during the manufacturing process
Benefits of new 7 quality control tool
Combine verbal with Numerical data
Looking for root cause
Clarify prioritize goals and schedule
Involve everyone into full cooperation and generate new ideas 1048577
The first new quality control tool is
1) Affinity Diagram
Application
An affinity diagram is used to organize into groupings large number of ideas opinions
or concerns about a Particular topic
Description
When a large number of ideas opinions or other concerns about a particular topic are
being collected this tool organizes the information into grouping~~based on the
natural relationships that exist among them The process is designed to stimulate
creativity and full participation It works best in groups of limited Size (a maximum
26
of eight members is recommended) in which members are accustomed to working
together This tool is often used to organize ideas generated by brainstorming
Procedure
State the topic to be studied in broad terms(details may prejudice the
response)
Record as many individual ideas opinions or concerns as possible on cards
(one per
card)
Mix the cards and spread them randomly on a large table
Group related cards together as follows
a)sort cards that seem to be related into groups and
b) limit number of grouping to ten without forcing single cards into groups
Locate or create a header card that captures the meaning of each group
Place this header card on top
Transfer the information from cards onto paper organized by groupings
Example For next generation digital camera we can organize the customer
Complains and requirements in an Affinity Diagram1048577
27
Affinity diagram
28
2) Tree diagram
Application
A tree diagram is used to show the interrelation between a topic and its component
elements
Description
A tree diagram systematically breaks down a topic into its component elements Ideas
generated by
Brainstorming and graphed or clustered with an affinity diagram can be converted
into a tree diagram
to show logical and sequential links This tool can be used in planning and problem
solving
Procedure
State the topic to be studied clearly
Define the major categories of the topic(brainstorm or use the header cards
from the affinity diagram)
Construct the diagram by placing the topic in a box on the left-hand side
Branch the major categories laterally to the right
For each major category define the component elements and sub-elements if
any
Laterally branch to the right the component elements and sub-elements for
each major category and
Review the diagram to ensure that there are no gaps in either sequence or
logic
29
30
3) Arrow diagram
Purpose To create a visual presentation of the steps of a process or tasks necessary to
complete a project with special emphasis on the time taken for these activities
Procedure
1 List all the tasks or activities needed to be accomplished before the process of the
project
2 Decide which steps are undertaken in series and which steps can be run in parallel
Arrange the
Activities in a proper sequence
3 Prepare lsquoEvent Nodesrsquo at the completion of steps and number them
4 Write the description of the step and decide the time required for completing each
step
5 Calculate the earliest time to reach an event node for the start of the process
7 Ager the time for all event nodes including the completion of the process or the
project is available one calculates the latest time by which an event node must be
reached
Application
The diagram is also useful in planning and scheduling steps in complicated processes
especially in planning and scheduling projects which involve a large number of
activities
Example
31
1 Identify the tasks Eg 123hellip15
2 Know the time each task needs
3 Determine which tasks can be run in parallel and in normal sequences
4 Draw the sequence diagram and find the critical path
5 Calculate the project duration
6 Calculate the earliest starting time (or the earliest finishing time of last task) and the
latest finishing time
of each task(the latest starting time for the following task)
7 Mark the time indication
32
33
4) Process Decision Program Chart (PDPC)
Def The process decision program chart (PDPC) method helps us select the best
processes to obtain optimum results by evaluating the progress of events and various
conceivable outcomes
Description
The process decision program chart (PDPC) method is used to define the solution
process when dealing with problems that have more than one possible outcome [t
anticipates the unexpected Outcomes at each stage and plans for it
PDPC has two following patterns
Pattern I ndash In this pattern process starts with initial condition lsquoArsquo and proceeds to the
desired final condition lsquoZrsquo in an organized manner
Pattern 11- In this pattern first the final conditionrsquosrsquo is set Then the process from lsquoZrsquo
to the initial point lsquoArsquo is developed with the inclusion of various alternatives from
many points of view
Procedure
Discuss the issues related to the project among a cross-functional team
Discuss which issues must be examined and identify those issues
Consider and note down all the anticipated results for the identified issues
Weigh the feasibility of each solution proposed and investigate alternate
solutions
Classify each issue according to its urgency number of operations required
likelihood of Occurrence and difficulty
Consider the anticipated results and alternative solutions related to issues that
must be addressed immediately and link the items with arrows to the desired
goal
34
Prioritize the different issues and consider them all together Information
related to one set of
Possibilities could influence another set Related items shall be linked with a
broken line
If the department that will handle a process involving several lines is
determined circle
the process and write the name of the department within
Set a target date for completion
Have regular meetings to check progress in terms of the original PDPC
35
36
37
38
5) Matrix diagram
Purpose1) Explore the existence and the extent of relations between individual items in 2 sets
of factors or features and characteristics and express them in a symbolic form that is
easy to understand
2) Mostly used to understand the relations between the customer expectations as
expressed by the customers and product characteristics as designed manufactured and
tested by the manufacturer
Procedures1 Determine 2 sets of factors for which the relations are needed to be established
2 Divide the features and characteristics into primary secondary and tertiary
characteristics
3 Place the features vertically on the leg side of the matrix and characteristics
horizontally on top of the matrix
4 Enter the importance of the features on the column ager that for the tertiary
features10485775 In the main body of the matrix use the symbols to represent the degree of
connections between the feature and characteristics
6 Choose and define relationship symbols Most commonly used symbols are as
given below
Strong relationship=
Relationship =
Likely relationship=
Application
bull Matrix diagram can be used to solve problems by arranging data in such a way that
the relations between relevant factors are brought into sharp focus
bull There is no limit to the use of the tool
39
bull The most important application of matrix diagram is in clarifying relations between
individual features of customer requirements and individual product characteristics
Example 1
Matrix Diagram for Quality Functions and Responsibilities
40
41
6) Matrix Data Analysis Diagram1048577
Purpose
To present numerical data about two sets of factors in a matrix form and
analyze it to get numerical output
Can be applied in understanding the products and products characteristics
Procedure1048577
1 Decide the two factors whose relations are to be analyzed
2 Check the number of individual items in the two factors
3 Prepare a matrix to accommodate all the items of the two factors
4 Enter numerical data in the matrix
5 Give the diagram a suitable title
Example
42
43
44
7) Relationship diagram
This diagram clarifies the interrelations in a complex situation involving many
interrelated factors and serves to clarify the cause and effect relationships among
factors
Description
Relations diagram is defined as a technique used to solve problems that have complex
cause and effect relationships among a number of problems and factors that influence
them
Format
A special feature of relation diagram is its unrestricted Format However general
formats are as given below
1) Centrally converging relations diagram
The major item or problem to be solved is located in the center and the related factors
are arranged around the item or problem in such a way as to indicate close
relationships
2) Directionally intensive relations diagram
The major item or problem to be solved is located on one side of the diagram and the
various factors arranged in accordance with the flow of their major cause-and-effect
relationships on the other side
3) Relationship indication relations diagram
There are no restrictions on this format because the main point is to arrange the cause-
and-effect Relationships of the application items or factors so that they are expressed
in a straightforward manner in a Diagram
45
Procedure
1) Define the issueproblem in such a way that it is clearly understood and agreed on
by team members
2) Assemble the cross-functional team
3) Layout all the ideasissue cards that have been brought from other tools
4) Look for causeinfluence relationships between all ideas and draw relationship
arrows
a) Choose any of the ideas as a starting point and work through them in sequence
b)An outgoing arrow from an idea indicates that it is the stronger cause or influence
c) Draw only one way relationship arrows in the direction of the stronger cause or
Influence Make a decision on the stronger direction Do not draw two headed arrows
5) Review and revise the relationsrsquo diagram
6) Tally the number of outgoing and incoming arrows and select key items for further
planning
-record and clearly mark next to each issue the number of arrows going in and out of
it
-find the items with the highest number outgoing arrows and the items with the
highest number of incoming arrows
-a high number of outgoing arrows indicate that the item is a root cause and should be
tackle first
46
-a high number of incoming arrows indicate that the item is a key outcome and may
become a focus for planning either as a meaningful measure of overall success or as a
redefinition of the original issue under discussion
Example
47
48
Conclusions
Statististical QC is chiefly concerned in making sure that several procedures
and working arrangements are in place to provide for effective and efficient
statistical processes to minimize the risk of errors or weaknesses in
procedures or systems or in source material
Seven QC tools are most helpful in troubleshooting issues related to quality
All processes are affected by multiple factors and therefore statistical QC tools
can be applied to any process
The continuous use of these tools upgrades the personnel characteristics of the
people involved It enhances their ability to think generate ideas solve
problem and do proper planning
49
References asqorglearn-about-qualityseven-basic-quality-toolsoverviewhtml
httpsenwikipediaorgwikiSeven_Basic_Tools_of_Quality
wwwijergsorgfilesdocumentsAPPLICATION-45pd
httpssrcalionsciencecompdfQualityToolspdf
www3haorghkqehwiserdoc7bqtpdf
wwwmathmunca~variyathNew7QCToolspd
50
- 1 DEFINITION of Quality Control
- 3 Competitiveness
- 4 Customer Loyalty
- 5 Reputation
- 6 Compliance
- 7 Costs
- Benefits of Using Quality Control in Manufacturing
-
4
Feature of this tools
DataorientationFocuson numericaldatameasure andcalculation
New 7 tools
Relationshipdiagram
Treediagram
Arrowdiagram
Affinitydiagram
Matrixdiagram
Matrixdataanalysis diagram
Processdecision programchart(PDPC)
Feature of new quality controls tools
Combineverbalwith numerical
Lookingforrootcause
Clarifyprioritizegoals andschedule
Involveeveryoneinto fullcooperation
Generateideas
5
Now starting with 1st quality control tools
1) Pareto chart or Pareto diagram
A Pareto chart is a bar graph The lengths of the bars represent frequency or cost (time
or money) and are arranged with longest bars on the left and the shortest to the right
In this way the chart visually depicts which situations are more significant
When to Use a Pareto Chart
When analyzing data about the frequency of problems or causes in a process
When there are many problems or causes and you want to focus on the most
significant
When analyzing broad causes by looking at their specific components
When communicating with others about your data
Pareto Chart Procedure
Decide what categories you will use to group items
Decide what measurement is appropriate Common measurements are
frequency quantity cost and time
Decide what period of time the Pareto chart will cover One work cycle One
full day A week
Collect the data recording the category each time (Or assemble data that
already exist)
Subtotal the measurements for each category
Determine the appropriate scale for the measurements you have collected The
maximum value will be the largest subtotal from step 5 (If you will do
optional steps 8 and 9 below the maximum value will be the sum of all
subtotals from step 5) Mark the scale on the left side of the chart
6
Construct and label bars for each category Place the tallest at the far left then
the next tallest to its right and so on If there are many categories with small
measurements they can be grouped as ldquootherrdquo
Steps 8 and 9 are optional but are useful for analysis and communication
Calculate the percentage for each category the subtotal for that category
divided by the total for all categories Draw a right vertical axis and label it
with percentages Be sure the two scales match For example the left
measurement that corresponds to one-half should be exactly opposite 50 on
the right scale
Calculate and draw cumulative sums Add the subtotals for the first and
second categories and place a dot above the second bar indicating that sum
To that sum add the subtotal for the third category and place a dot above the
third bar for that new sum Continue the process for all the bars Connect the
dots starting at the top of the first bar The last dot should reach 100 percent
on the right scale
Pareto Chart Examples
Example 1 shows how many customer complaints were received in each of five
categories
Example 2 takes the largest category ldquodocumentsrdquo from Example 1 breaks it
down into six categories of document-related complaints and shows cumulative
values
If all complaints cause equal distress to the customer working on eliminating
document-related complaints would have the most impact and of those working on
quality certificates should be most fruitful
7
8
2) The fishbone diagram
A Cause-and Effect Diagram also known as fish bone diagram is a tool that shows
systematic relationship between a result or a symptom or an effect and its possible
causes It is an effective tool to systematically generate ideas about causes for
problems and to present these in a structured form This tool was devised by Dr
Kouro Ishikawa and as mentioned earlier is also known as Ishikawa Diagram
Procedure
The steps in the procedure to prepare a cause-and-effect diagram are
1 Agree on the definition of the Effect for which causes are to be found Place the
effect in the dark box at the right Draw the spine or the backbone as a dark line
leading to the box for the effect
1 Determine the main groups or categories of causes Place them in boxes and
connect them through large bones to the backbone
2 Brainstorm to find possible causes and subsidiary causes under each of the main
groups Make sure that the route from the cause to the effect is correctly depicted The
path must start from a root cause and end in the effect
3 After completing all the main groups brainstorm for more causes that may have
escaped earlier
4 Once the diagram is complete discuss relative importance of the causes Short list
the important root causes
9
10
3) Check sheets
Also called defect concentration diagram A check sheet is a structured prepared
form for collecting and analyzing data This is a generic tool that can be adapted for a
wide variety of purposes
When to Use a Check Sheet
When data can be observed and collected repeatedly by the same person or at
the same location
When collecting data on the frequency or patterns of events problems
defects defect location defect causes etc
When collecting data from a production process
Check Sheet Procedure
Decide what event or problem will be observed Develop operational
definitions
Decide when data will be collected and for how long
Design the form Set it up so that data can be recorded simply by making
check marks or Xs or similar symbols and so that data do not have to be
recopied for analysis
Label all spaces on the form
Test the check sheet for a short trial period to be sure it collects the
appropriate data and is easy to use
Each time the targeted event or problem occurs record data on the check
sheet
Check Sheet Example
The figure below shows a check sheet used to collect data on telephone interruptions
The tick marks were added as data was collected over several weeks
11
12
4) Control chart
The control chart is a graph used to study how a process changes over time Data are
plotted in time order A control chart always has a central line for the average an
upper line for the upper control limit and a lower line for the lower control limit
These lines are determined from historical data By comparing current data to these
lines you can draw conclusions about whether the process variation is consistent (in
control) or is unpredictable (out of control affected by special causes of variation)
Control charts for variable data are used in pairs The top chart monitors the average
or the centring of the distribution of data from the process The bottom chart monitors
the range or the width of the distribution If your data were shots in target practice
the average is where the shots are clustering and the range is how tightly they are
clustered Control charts for attribute data are used singly
41 When to Use a Control Chart
When controlling ongoing processes by finding and correcting problems as they
occur
When predicting the expected range of outcomes from a process
When determining whether a process is stable (in statistical control)
When analyzing patterns of process variation from special causes (non-routine
events) or common causes (built into the process)
When determining whether your quality improvement project should aim to
prevent specific problems or to make fundamental changes to the process
Control Chart Basic Procedure
Choose the appropriate control chart for your data
Determine the appropriate time period for collecting and plotting data
13
Collect data construct your chart and analyze the data
Look for ldquoout-of-control signalsrdquo on the control chart When one is identified mark it
on the chart and investigate the cause Document how you investigated what you
learned the cause and how it was corrected
Out-of-control signals
A single point outside the control limits In Figure 1 point sixteen is above the UCL
(upper control limit)
Two out of three successive points are on the same side of the centreline and farther
than 2 σ from it In Figure 1 point 4 sends that signal
Four out of five successive points are on the same side of the centreline and farther
than 1 σ from it In Figure 1 point 11 sends that signal
A run of eight in a row are on the same side of the centreline Or 10 out of 11 12 out
of 14 or 16 out of 20 In Figure 1 point 21 is eighth in a row above the centreline
Obvious consistent or persistent patterns that suggest something unusual about your
data and your process
5 Continue to plot data as they are generated As each new data point is plotted
check for new out-of-control signals
14
6 When you start a new control chart the process may be out of control If so the
control limits calculated from the first 20 points are conditional limits When you
have at least 20 sequential points from a period when the process is operating in
control recalculate control limits
5) Histogram chart
A frequency distribution shows how often each different value in a set of data occurs
A histogram is the most commonly used graph to show frequency distributions It
looks very much like a bar chart but there are important differences between them
When to Use a Histogram
When the data are numerical
When you want to see the shape of the datarsquos distribution especially when
determining whether the output of a process is distributed approximately
normally
When analyzing whether a process can meet the customerrsquos requirements
When analyzing what the output from a supplierrsquos process looks like
When seeing whether a process change has occurred from one time period to
another
When determining whether the outputs of two or more processes are different
When you wish to communicate the distribution of data quickly and easily to
others
Histogram Construction
Collect at least 50 consecutive data points from a process
Use the histogram worksheet to set up the histogram It will help you determine the
number of bars the range of numbers that go into each bar and the labels for the bar
edges After calculating W in step 2 of the worksheet use your judgment to adjust it
to a convenient number For example you might decide to round 09 to an even 10
15
The value for W must not have more decimal places than the numbers you will be
graphing
Draw x- and y-axes on graph paper Mark and label the y-axis for counting data
values Mark and label the x-axis with the L values from the worksheet The spaces
between these numbers will be the bars of the histogram Do not allow for spaces
between bars
For each data point mark off one count above the appropriate bar with an X or by
shading that portion of the bar
Histogram Analysis
Before drawing any conclusions from your histogram satisfy yourself that the process
was operating normally during the time period being studied If any unusual events
affected the process during the time period of the histogram your analysis of the
histogram shape probably cannot be generalized to all time periods
Analyze the meaning of your histogramrsquo
16
17
6) Scatter chart
The scatter diagram graphs pairs of numerical data with one variable on each axis to
look for a relationship between them If the variables are correlated the points will
fall along a line or curve The better the correlation the tighter the points will hug the
line
When to Use a Scatter Diagram
When you have paired numerical data
When your dependent variable may have multiple values for each value of your
independent variable
When trying to determine whether the two variables are related such ashellip
When trying to identify potential root causes of problems
After brainstorming causes and effects using a fishbone diagram to determine
objectively whether a particular cause and effect are related
When determining whether two effects that appears to be related both occur with the
same cause
When testing for autocorrelation before constructing a control chart
Scatter Diagram Procedure
Collect pairs of data where a relationship is suspected
Draw a graph with the independent variable on the horizontal axis and the dependent
variable on the vertical axis For each pair of data put a dot or a symbol where the x-
axis value intersects the y-axis value (If two dots fall together put them side by side
touching so that you can see both)
18
Look at the pattern of points to see if a relationship is obvious If the data clearly form
a line or a curve you may stop The variables are correlated You may wish to use
regression or correlation analysis now Otherwise complete steps 4 through 7
Divide points on the graph into four quadrants If there are X points on the graph
Count X2 points from top to bottom and draw a horizontal line
Count X2 points from left to right and draw a vertical line
If number of points is odd draw the line through the middle point
Count the points in each quadrant Do not count points on a line
Add the diagonally opposite quadrants Find the smaller sum and the total of points in
all quadrants
A = points in upper left + points in lower right
B = points in upper right + points in lower left
Q = the smaller of A and B
N = A + B
Look up the limit for N on the trend test table
If Q is less than the limit the two variables are related
If Q is greater than or equal to the limit the pattern could have occurred from random
chance
19
Scatter Diagram Example
The ZZ-400 manufacturing team suspects a relationship between product purity
(percent purity) and the amount of iron (measured in parts per million or ppm) Purity
and iron are plotted against each other as a scatter diagram as shown in the figure
below
There are 24 data points Median lines are drawn so that 12 points fall on each side for
both percent purity and ppm iron
To test for a relationship they calculate
A = points in upper left + points in lower right = 9 + 9 = 18
B = points in upper right + points in lower left = 3 + 3 = 6
Q = the smaller of A and B = the smaller of 18 and 6 = 6
N = A + B = 18 + 6 = 24
20
Then they look up the limit for N on the trend test table For N = 24 the limit is 6
Q is equal to the limit Therefore the pattern could have occurred from random
chance and no relationship is demonstrated
Scatter Diagram Example
Scatter Diagram Considerations
Here are some examples of situations in which might you use a scatter diagram
Variable A is the temperature of a reaction after 15 minutes Variable B measures the
colour of the product You suspect higher temperature makes the product darker Plot
temperature and colour on a scatter diagram
Variable A is the number of employees trained on new software and variable B is the
number of calls to the computer helps line You suspect that more training reduces the
number of calls Plot number of people trained versus number of calls
To test for autocorrelation of a measurement being monitored on a control chart plot
this pair of variables Variable A is the measurement at a given time Variable B is the
same measurement but at the previous time If the scatter diagram shows correlation
do another diagram where variable B is the measurement two times previously Keep
increasing the separation between the two times until the scatter diagram shows no
correlation
21
Even if the scatter diagram shows a relationship do not assume that one variable
caused the other Both may be influenced by a third variable
When the data are plotted the more the diagram resembles a straight line the stronger
the relationship
If a line is not clear statistics (N and Q) determine whether there is reasonable
certainty that a relationship exists If the statistics say that no relationship exists the
pattern could have occurred by random chance
If the scatter diagram shows no relationship between the variables consider whether
the data might be stratified
If the diagram shows no relationship consider whether the independent (x-axis)
variable has been varied widely Sometimes a relationship is not apparent because the
data donrsquot cover a wide enough range
Think creatively about how to use scatter diagrams to discover a root cause
Drawing a scatter diagram is the first step in looking for a relationship between
variables
22
7) Stratification
Stratification is a technique used in combination with other data analysis tools When
data from a variety of sources or categories have been lumped together the meaning
of the data can be impossible to see This technique separates the data so that patterns
can be seen
When to Use Stratification
Before collecting data
When data come from several sources or conditions such as shifts days of the
week suppliers or population groups
When data analysis may require separating different sources or conditions
Stratification Procedure
Before collecting data consider which information about the sources of the data
might have an effect on the results Set up the data collection so that you collect that
information as well
When plotting or graphing the collected data on a scatter diagram control chart
histogram or other analysis tool use different marks or colours to distinguish data
from various sources Data that are distinguished in this way are said to be
ldquostratifiedrdquo
Analyze the subsets of stratified data separately For example on a scatter diagram
where data are stratified into data from source 1 and data from source 2 draw
quadrants count points and determine the critical value only for the data from source
1 then only for the data from source 2
Stratification Example
23
The ZZndash400 manufacturing team drew a scatter diagram to test whether product
purity and iron contamination were related but the plot did not demonstrate a
relationship Then a team member realized that the data came from three different
reactors The team member redrew the diagram using a different symbol for each
reactorrsquos data
Now patterns can be seen The data from reactor 2 and reactor 3 are circled Even
without doing any calculations it is clear that for those two reactors purity decreases
as iron increases However the data from reactor 1 the solid dots that are not circled
do not show that relationship Something is different about reactor 1
Stratification Considerations
Here are examples of different sources that might require data to be stratified
Equipment
Shifts
Departments
24
Materials
Suppliers
Day of the week
Time of day
Products
Survey data usually benefit from stratification
Always consider before collecting data whether stratification might be needed during
analysis Plan to collect stratification information After the data are collected it might
be too late
On your graph or chart include a legend that identifies the marks or colours used
25
Now starting with new 7 quality control tool
Need of new quality control tool
Many customer requirements cannot always be adequately expressed by numerical
data alone Nevertheless even verbal statements can be expressions of facts because
it represents facts we ought to use Verbal data as well as numerical data in
controlling the managing quality It provides both quality control as well as
improvement during the manufacturing process
Benefits of new 7 quality control tool
Combine verbal with Numerical data
Looking for root cause
Clarify prioritize goals and schedule
Involve everyone into full cooperation and generate new ideas 1048577
The first new quality control tool is
1) Affinity Diagram
Application
An affinity diagram is used to organize into groupings large number of ideas opinions
or concerns about a Particular topic
Description
When a large number of ideas opinions or other concerns about a particular topic are
being collected this tool organizes the information into grouping~~based on the
natural relationships that exist among them The process is designed to stimulate
creativity and full participation It works best in groups of limited Size (a maximum
26
of eight members is recommended) in which members are accustomed to working
together This tool is often used to organize ideas generated by brainstorming
Procedure
State the topic to be studied in broad terms(details may prejudice the
response)
Record as many individual ideas opinions or concerns as possible on cards
(one per
card)
Mix the cards and spread them randomly on a large table
Group related cards together as follows
a)sort cards that seem to be related into groups and
b) limit number of grouping to ten without forcing single cards into groups
Locate or create a header card that captures the meaning of each group
Place this header card on top
Transfer the information from cards onto paper organized by groupings
Example For next generation digital camera we can organize the customer
Complains and requirements in an Affinity Diagram1048577
27
Affinity diagram
28
2) Tree diagram
Application
A tree diagram is used to show the interrelation between a topic and its component
elements
Description
A tree diagram systematically breaks down a topic into its component elements Ideas
generated by
Brainstorming and graphed or clustered with an affinity diagram can be converted
into a tree diagram
to show logical and sequential links This tool can be used in planning and problem
solving
Procedure
State the topic to be studied clearly
Define the major categories of the topic(brainstorm or use the header cards
from the affinity diagram)
Construct the diagram by placing the topic in a box on the left-hand side
Branch the major categories laterally to the right
For each major category define the component elements and sub-elements if
any
Laterally branch to the right the component elements and sub-elements for
each major category and
Review the diagram to ensure that there are no gaps in either sequence or
logic
29
30
3) Arrow diagram
Purpose To create a visual presentation of the steps of a process or tasks necessary to
complete a project with special emphasis on the time taken for these activities
Procedure
1 List all the tasks or activities needed to be accomplished before the process of the
project
2 Decide which steps are undertaken in series and which steps can be run in parallel
Arrange the
Activities in a proper sequence
3 Prepare lsquoEvent Nodesrsquo at the completion of steps and number them
4 Write the description of the step and decide the time required for completing each
step
5 Calculate the earliest time to reach an event node for the start of the process
7 Ager the time for all event nodes including the completion of the process or the
project is available one calculates the latest time by which an event node must be
reached
Application
The diagram is also useful in planning and scheduling steps in complicated processes
especially in planning and scheduling projects which involve a large number of
activities
Example
31
1 Identify the tasks Eg 123hellip15
2 Know the time each task needs
3 Determine which tasks can be run in parallel and in normal sequences
4 Draw the sequence diagram and find the critical path
5 Calculate the project duration
6 Calculate the earliest starting time (or the earliest finishing time of last task) and the
latest finishing time
of each task(the latest starting time for the following task)
7 Mark the time indication
32
33
4) Process Decision Program Chart (PDPC)
Def The process decision program chart (PDPC) method helps us select the best
processes to obtain optimum results by evaluating the progress of events and various
conceivable outcomes
Description
The process decision program chart (PDPC) method is used to define the solution
process when dealing with problems that have more than one possible outcome [t
anticipates the unexpected Outcomes at each stage and plans for it
PDPC has two following patterns
Pattern I ndash In this pattern process starts with initial condition lsquoArsquo and proceeds to the
desired final condition lsquoZrsquo in an organized manner
Pattern 11- In this pattern first the final conditionrsquosrsquo is set Then the process from lsquoZrsquo
to the initial point lsquoArsquo is developed with the inclusion of various alternatives from
many points of view
Procedure
Discuss the issues related to the project among a cross-functional team
Discuss which issues must be examined and identify those issues
Consider and note down all the anticipated results for the identified issues
Weigh the feasibility of each solution proposed and investigate alternate
solutions
Classify each issue according to its urgency number of operations required
likelihood of Occurrence and difficulty
Consider the anticipated results and alternative solutions related to issues that
must be addressed immediately and link the items with arrows to the desired
goal
34
Prioritize the different issues and consider them all together Information
related to one set of
Possibilities could influence another set Related items shall be linked with a
broken line
If the department that will handle a process involving several lines is
determined circle
the process and write the name of the department within
Set a target date for completion
Have regular meetings to check progress in terms of the original PDPC
35
36
37
38
5) Matrix diagram
Purpose1) Explore the existence and the extent of relations between individual items in 2 sets
of factors or features and characteristics and express them in a symbolic form that is
easy to understand
2) Mostly used to understand the relations between the customer expectations as
expressed by the customers and product characteristics as designed manufactured and
tested by the manufacturer
Procedures1 Determine 2 sets of factors for which the relations are needed to be established
2 Divide the features and characteristics into primary secondary and tertiary
characteristics
3 Place the features vertically on the leg side of the matrix and characteristics
horizontally on top of the matrix
4 Enter the importance of the features on the column ager that for the tertiary
features10485775 In the main body of the matrix use the symbols to represent the degree of
connections between the feature and characteristics
6 Choose and define relationship symbols Most commonly used symbols are as
given below
Strong relationship=
Relationship =
Likely relationship=
Application
bull Matrix diagram can be used to solve problems by arranging data in such a way that
the relations between relevant factors are brought into sharp focus
bull There is no limit to the use of the tool
39
bull The most important application of matrix diagram is in clarifying relations between
individual features of customer requirements and individual product characteristics
Example 1
Matrix Diagram for Quality Functions and Responsibilities
40
41
6) Matrix Data Analysis Diagram1048577
Purpose
To present numerical data about two sets of factors in a matrix form and
analyze it to get numerical output
Can be applied in understanding the products and products characteristics
Procedure1048577
1 Decide the two factors whose relations are to be analyzed
2 Check the number of individual items in the two factors
3 Prepare a matrix to accommodate all the items of the two factors
4 Enter numerical data in the matrix
5 Give the diagram a suitable title
Example
42
43
44
7) Relationship diagram
This diagram clarifies the interrelations in a complex situation involving many
interrelated factors and serves to clarify the cause and effect relationships among
factors
Description
Relations diagram is defined as a technique used to solve problems that have complex
cause and effect relationships among a number of problems and factors that influence
them
Format
A special feature of relation diagram is its unrestricted Format However general
formats are as given below
1) Centrally converging relations diagram
The major item or problem to be solved is located in the center and the related factors
are arranged around the item or problem in such a way as to indicate close
relationships
2) Directionally intensive relations diagram
The major item or problem to be solved is located on one side of the diagram and the
various factors arranged in accordance with the flow of their major cause-and-effect
relationships on the other side
3) Relationship indication relations diagram
There are no restrictions on this format because the main point is to arrange the cause-
and-effect Relationships of the application items or factors so that they are expressed
in a straightforward manner in a Diagram
45
Procedure
1) Define the issueproblem in such a way that it is clearly understood and agreed on
by team members
2) Assemble the cross-functional team
3) Layout all the ideasissue cards that have been brought from other tools
4) Look for causeinfluence relationships between all ideas and draw relationship
arrows
a) Choose any of the ideas as a starting point and work through them in sequence
b)An outgoing arrow from an idea indicates that it is the stronger cause or influence
c) Draw only one way relationship arrows in the direction of the stronger cause or
Influence Make a decision on the stronger direction Do not draw two headed arrows
5) Review and revise the relationsrsquo diagram
6) Tally the number of outgoing and incoming arrows and select key items for further
planning
-record and clearly mark next to each issue the number of arrows going in and out of
it
-find the items with the highest number outgoing arrows and the items with the
highest number of incoming arrows
-a high number of outgoing arrows indicate that the item is a root cause and should be
tackle first
46
-a high number of incoming arrows indicate that the item is a key outcome and may
become a focus for planning either as a meaningful measure of overall success or as a
redefinition of the original issue under discussion
Example
47
48
Conclusions
Statististical QC is chiefly concerned in making sure that several procedures
and working arrangements are in place to provide for effective and efficient
statistical processes to minimize the risk of errors or weaknesses in
procedures or systems or in source material
Seven QC tools are most helpful in troubleshooting issues related to quality
All processes are affected by multiple factors and therefore statistical QC tools
can be applied to any process
The continuous use of these tools upgrades the personnel characteristics of the
people involved It enhances their ability to think generate ideas solve
problem and do proper planning
49
References asqorglearn-about-qualityseven-basic-quality-toolsoverviewhtml
httpsenwikipediaorgwikiSeven_Basic_Tools_of_Quality
wwwijergsorgfilesdocumentsAPPLICATION-45pd
httpssrcalionsciencecompdfQualityToolspdf
www3haorghkqehwiserdoc7bqtpdf
wwwmathmunca~variyathNew7QCToolspd
50
- 1 DEFINITION of Quality Control
- 3 Competitiveness
- 4 Customer Loyalty
- 5 Reputation
- 6 Compliance
- 7 Costs
- Benefits of Using Quality Control in Manufacturing
-
Feature of this tools
DataorientationFocuson numericaldatameasure andcalculation
New 7 tools
Relationshipdiagram
Treediagram
Arrowdiagram
Affinitydiagram
Matrixdiagram
Matrixdataanalysis diagram
Processdecision programchart(PDPC)
Feature of new quality controls tools
Combineverbalwith numerical
Lookingforrootcause
Clarifyprioritizegoals andschedule
Involveeveryoneinto fullcooperation
Generateideas
5
Now starting with 1st quality control tools
1) Pareto chart or Pareto diagram
A Pareto chart is a bar graph The lengths of the bars represent frequency or cost (time
or money) and are arranged with longest bars on the left and the shortest to the right
In this way the chart visually depicts which situations are more significant
When to Use a Pareto Chart
When analyzing data about the frequency of problems or causes in a process
When there are many problems or causes and you want to focus on the most
significant
When analyzing broad causes by looking at their specific components
When communicating with others about your data
Pareto Chart Procedure
Decide what categories you will use to group items
Decide what measurement is appropriate Common measurements are
frequency quantity cost and time
Decide what period of time the Pareto chart will cover One work cycle One
full day A week
Collect the data recording the category each time (Or assemble data that
already exist)
Subtotal the measurements for each category
Determine the appropriate scale for the measurements you have collected The
maximum value will be the largest subtotal from step 5 (If you will do
optional steps 8 and 9 below the maximum value will be the sum of all
subtotals from step 5) Mark the scale on the left side of the chart
6
Construct and label bars for each category Place the tallest at the far left then
the next tallest to its right and so on If there are many categories with small
measurements they can be grouped as ldquootherrdquo
Steps 8 and 9 are optional but are useful for analysis and communication
Calculate the percentage for each category the subtotal for that category
divided by the total for all categories Draw a right vertical axis and label it
with percentages Be sure the two scales match For example the left
measurement that corresponds to one-half should be exactly opposite 50 on
the right scale
Calculate and draw cumulative sums Add the subtotals for the first and
second categories and place a dot above the second bar indicating that sum
To that sum add the subtotal for the third category and place a dot above the
third bar for that new sum Continue the process for all the bars Connect the
dots starting at the top of the first bar The last dot should reach 100 percent
on the right scale
Pareto Chart Examples
Example 1 shows how many customer complaints were received in each of five
categories
Example 2 takes the largest category ldquodocumentsrdquo from Example 1 breaks it
down into six categories of document-related complaints and shows cumulative
values
If all complaints cause equal distress to the customer working on eliminating
document-related complaints would have the most impact and of those working on
quality certificates should be most fruitful
7
8
2) The fishbone diagram
A Cause-and Effect Diagram also known as fish bone diagram is a tool that shows
systematic relationship between a result or a symptom or an effect and its possible
causes It is an effective tool to systematically generate ideas about causes for
problems and to present these in a structured form This tool was devised by Dr
Kouro Ishikawa and as mentioned earlier is also known as Ishikawa Diagram
Procedure
The steps in the procedure to prepare a cause-and-effect diagram are
1 Agree on the definition of the Effect for which causes are to be found Place the
effect in the dark box at the right Draw the spine or the backbone as a dark line
leading to the box for the effect
1 Determine the main groups or categories of causes Place them in boxes and
connect them through large bones to the backbone
2 Brainstorm to find possible causes and subsidiary causes under each of the main
groups Make sure that the route from the cause to the effect is correctly depicted The
path must start from a root cause and end in the effect
3 After completing all the main groups brainstorm for more causes that may have
escaped earlier
4 Once the diagram is complete discuss relative importance of the causes Short list
the important root causes
9
10
3) Check sheets
Also called defect concentration diagram A check sheet is a structured prepared
form for collecting and analyzing data This is a generic tool that can be adapted for a
wide variety of purposes
When to Use a Check Sheet
When data can be observed and collected repeatedly by the same person or at
the same location
When collecting data on the frequency or patterns of events problems
defects defect location defect causes etc
When collecting data from a production process
Check Sheet Procedure
Decide what event or problem will be observed Develop operational
definitions
Decide when data will be collected and for how long
Design the form Set it up so that data can be recorded simply by making
check marks or Xs or similar symbols and so that data do not have to be
recopied for analysis
Label all spaces on the form
Test the check sheet for a short trial period to be sure it collects the
appropriate data and is easy to use
Each time the targeted event or problem occurs record data on the check
sheet
Check Sheet Example
The figure below shows a check sheet used to collect data on telephone interruptions
The tick marks were added as data was collected over several weeks
11
12
4) Control chart
The control chart is a graph used to study how a process changes over time Data are
plotted in time order A control chart always has a central line for the average an
upper line for the upper control limit and a lower line for the lower control limit
These lines are determined from historical data By comparing current data to these
lines you can draw conclusions about whether the process variation is consistent (in
control) or is unpredictable (out of control affected by special causes of variation)
Control charts for variable data are used in pairs The top chart monitors the average
or the centring of the distribution of data from the process The bottom chart monitors
the range or the width of the distribution If your data were shots in target practice
the average is where the shots are clustering and the range is how tightly they are
clustered Control charts for attribute data are used singly
41 When to Use a Control Chart
When controlling ongoing processes by finding and correcting problems as they
occur
When predicting the expected range of outcomes from a process
When determining whether a process is stable (in statistical control)
When analyzing patterns of process variation from special causes (non-routine
events) or common causes (built into the process)
When determining whether your quality improvement project should aim to
prevent specific problems or to make fundamental changes to the process
Control Chart Basic Procedure
Choose the appropriate control chart for your data
Determine the appropriate time period for collecting and plotting data
13
Collect data construct your chart and analyze the data
Look for ldquoout-of-control signalsrdquo on the control chart When one is identified mark it
on the chart and investigate the cause Document how you investigated what you
learned the cause and how it was corrected
Out-of-control signals
A single point outside the control limits In Figure 1 point sixteen is above the UCL
(upper control limit)
Two out of three successive points are on the same side of the centreline and farther
than 2 σ from it In Figure 1 point 4 sends that signal
Four out of five successive points are on the same side of the centreline and farther
than 1 σ from it In Figure 1 point 11 sends that signal
A run of eight in a row are on the same side of the centreline Or 10 out of 11 12 out
of 14 or 16 out of 20 In Figure 1 point 21 is eighth in a row above the centreline
Obvious consistent or persistent patterns that suggest something unusual about your
data and your process
5 Continue to plot data as they are generated As each new data point is plotted
check for new out-of-control signals
14
6 When you start a new control chart the process may be out of control If so the
control limits calculated from the first 20 points are conditional limits When you
have at least 20 sequential points from a period when the process is operating in
control recalculate control limits
5) Histogram chart
A frequency distribution shows how often each different value in a set of data occurs
A histogram is the most commonly used graph to show frequency distributions It
looks very much like a bar chart but there are important differences between them
When to Use a Histogram
When the data are numerical
When you want to see the shape of the datarsquos distribution especially when
determining whether the output of a process is distributed approximately
normally
When analyzing whether a process can meet the customerrsquos requirements
When analyzing what the output from a supplierrsquos process looks like
When seeing whether a process change has occurred from one time period to
another
When determining whether the outputs of two or more processes are different
When you wish to communicate the distribution of data quickly and easily to
others
Histogram Construction
Collect at least 50 consecutive data points from a process
Use the histogram worksheet to set up the histogram It will help you determine the
number of bars the range of numbers that go into each bar and the labels for the bar
edges After calculating W in step 2 of the worksheet use your judgment to adjust it
to a convenient number For example you might decide to round 09 to an even 10
15
The value for W must not have more decimal places than the numbers you will be
graphing
Draw x- and y-axes on graph paper Mark and label the y-axis for counting data
values Mark and label the x-axis with the L values from the worksheet The spaces
between these numbers will be the bars of the histogram Do not allow for spaces
between bars
For each data point mark off one count above the appropriate bar with an X or by
shading that portion of the bar
Histogram Analysis
Before drawing any conclusions from your histogram satisfy yourself that the process
was operating normally during the time period being studied If any unusual events
affected the process during the time period of the histogram your analysis of the
histogram shape probably cannot be generalized to all time periods
Analyze the meaning of your histogramrsquo
16
17
6) Scatter chart
The scatter diagram graphs pairs of numerical data with one variable on each axis to
look for a relationship between them If the variables are correlated the points will
fall along a line or curve The better the correlation the tighter the points will hug the
line
When to Use a Scatter Diagram
When you have paired numerical data
When your dependent variable may have multiple values for each value of your
independent variable
When trying to determine whether the two variables are related such ashellip
When trying to identify potential root causes of problems
After brainstorming causes and effects using a fishbone diagram to determine
objectively whether a particular cause and effect are related
When determining whether two effects that appears to be related both occur with the
same cause
When testing for autocorrelation before constructing a control chart
Scatter Diagram Procedure
Collect pairs of data where a relationship is suspected
Draw a graph with the independent variable on the horizontal axis and the dependent
variable on the vertical axis For each pair of data put a dot or a symbol where the x-
axis value intersects the y-axis value (If two dots fall together put them side by side
touching so that you can see both)
18
Look at the pattern of points to see if a relationship is obvious If the data clearly form
a line or a curve you may stop The variables are correlated You may wish to use
regression or correlation analysis now Otherwise complete steps 4 through 7
Divide points on the graph into four quadrants If there are X points on the graph
Count X2 points from top to bottom and draw a horizontal line
Count X2 points from left to right and draw a vertical line
If number of points is odd draw the line through the middle point
Count the points in each quadrant Do not count points on a line
Add the diagonally opposite quadrants Find the smaller sum and the total of points in
all quadrants
A = points in upper left + points in lower right
B = points in upper right + points in lower left
Q = the smaller of A and B
N = A + B
Look up the limit for N on the trend test table
If Q is less than the limit the two variables are related
If Q is greater than or equal to the limit the pattern could have occurred from random
chance
19
Scatter Diagram Example
The ZZ-400 manufacturing team suspects a relationship between product purity
(percent purity) and the amount of iron (measured in parts per million or ppm) Purity
and iron are plotted against each other as a scatter diagram as shown in the figure
below
There are 24 data points Median lines are drawn so that 12 points fall on each side for
both percent purity and ppm iron
To test for a relationship they calculate
A = points in upper left + points in lower right = 9 + 9 = 18
B = points in upper right + points in lower left = 3 + 3 = 6
Q = the smaller of A and B = the smaller of 18 and 6 = 6
N = A + B = 18 + 6 = 24
20
Then they look up the limit for N on the trend test table For N = 24 the limit is 6
Q is equal to the limit Therefore the pattern could have occurred from random
chance and no relationship is demonstrated
Scatter Diagram Example
Scatter Diagram Considerations
Here are some examples of situations in which might you use a scatter diagram
Variable A is the temperature of a reaction after 15 minutes Variable B measures the
colour of the product You suspect higher temperature makes the product darker Plot
temperature and colour on a scatter diagram
Variable A is the number of employees trained on new software and variable B is the
number of calls to the computer helps line You suspect that more training reduces the
number of calls Plot number of people trained versus number of calls
To test for autocorrelation of a measurement being monitored on a control chart plot
this pair of variables Variable A is the measurement at a given time Variable B is the
same measurement but at the previous time If the scatter diagram shows correlation
do another diagram where variable B is the measurement two times previously Keep
increasing the separation between the two times until the scatter diagram shows no
correlation
21
Even if the scatter diagram shows a relationship do not assume that one variable
caused the other Both may be influenced by a third variable
When the data are plotted the more the diagram resembles a straight line the stronger
the relationship
If a line is not clear statistics (N and Q) determine whether there is reasonable
certainty that a relationship exists If the statistics say that no relationship exists the
pattern could have occurred by random chance
If the scatter diagram shows no relationship between the variables consider whether
the data might be stratified
If the diagram shows no relationship consider whether the independent (x-axis)
variable has been varied widely Sometimes a relationship is not apparent because the
data donrsquot cover a wide enough range
Think creatively about how to use scatter diagrams to discover a root cause
Drawing a scatter diagram is the first step in looking for a relationship between
variables
22
7) Stratification
Stratification is a technique used in combination with other data analysis tools When
data from a variety of sources or categories have been lumped together the meaning
of the data can be impossible to see This technique separates the data so that patterns
can be seen
When to Use Stratification
Before collecting data
When data come from several sources or conditions such as shifts days of the
week suppliers or population groups
When data analysis may require separating different sources or conditions
Stratification Procedure
Before collecting data consider which information about the sources of the data
might have an effect on the results Set up the data collection so that you collect that
information as well
When plotting or graphing the collected data on a scatter diagram control chart
histogram or other analysis tool use different marks or colours to distinguish data
from various sources Data that are distinguished in this way are said to be
ldquostratifiedrdquo
Analyze the subsets of stratified data separately For example on a scatter diagram
where data are stratified into data from source 1 and data from source 2 draw
quadrants count points and determine the critical value only for the data from source
1 then only for the data from source 2
Stratification Example
23
The ZZndash400 manufacturing team drew a scatter diagram to test whether product
purity and iron contamination were related but the plot did not demonstrate a
relationship Then a team member realized that the data came from three different
reactors The team member redrew the diagram using a different symbol for each
reactorrsquos data
Now patterns can be seen The data from reactor 2 and reactor 3 are circled Even
without doing any calculations it is clear that for those two reactors purity decreases
as iron increases However the data from reactor 1 the solid dots that are not circled
do not show that relationship Something is different about reactor 1
Stratification Considerations
Here are examples of different sources that might require data to be stratified
Equipment
Shifts
Departments
24
Materials
Suppliers
Day of the week
Time of day
Products
Survey data usually benefit from stratification
Always consider before collecting data whether stratification might be needed during
analysis Plan to collect stratification information After the data are collected it might
be too late
On your graph or chart include a legend that identifies the marks or colours used
25
Now starting with new 7 quality control tool
Need of new quality control tool
Many customer requirements cannot always be adequately expressed by numerical
data alone Nevertheless even verbal statements can be expressions of facts because
it represents facts we ought to use Verbal data as well as numerical data in
controlling the managing quality It provides both quality control as well as
improvement during the manufacturing process
Benefits of new 7 quality control tool
Combine verbal with Numerical data
Looking for root cause
Clarify prioritize goals and schedule
Involve everyone into full cooperation and generate new ideas 1048577
The first new quality control tool is
1) Affinity Diagram
Application
An affinity diagram is used to organize into groupings large number of ideas opinions
or concerns about a Particular topic
Description
When a large number of ideas opinions or other concerns about a particular topic are
being collected this tool organizes the information into grouping~~based on the
natural relationships that exist among them The process is designed to stimulate
creativity and full participation It works best in groups of limited Size (a maximum
26
of eight members is recommended) in which members are accustomed to working
together This tool is often used to organize ideas generated by brainstorming
Procedure
State the topic to be studied in broad terms(details may prejudice the
response)
Record as many individual ideas opinions or concerns as possible on cards
(one per
card)
Mix the cards and spread them randomly on a large table
Group related cards together as follows
a)sort cards that seem to be related into groups and
b) limit number of grouping to ten without forcing single cards into groups
Locate or create a header card that captures the meaning of each group
Place this header card on top
Transfer the information from cards onto paper organized by groupings
Example For next generation digital camera we can organize the customer
Complains and requirements in an Affinity Diagram1048577
27
Affinity diagram
28
2) Tree diagram
Application
A tree diagram is used to show the interrelation between a topic and its component
elements
Description
A tree diagram systematically breaks down a topic into its component elements Ideas
generated by
Brainstorming and graphed or clustered with an affinity diagram can be converted
into a tree diagram
to show logical and sequential links This tool can be used in planning and problem
solving
Procedure
State the topic to be studied clearly
Define the major categories of the topic(brainstorm or use the header cards
from the affinity diagram)
Construct the diagram by placing the topic in a box on the left-hand side
Branch the major categories laterally to the right
For each major category define the component elements and sub-elements if
any
Laterally branch to the right the component elements and sub-elements for
each major category and
Review the diagram to ensure that there are no gaps in either sequence or
logic
29
30
3) Arrow diagram
Purpose To create a visual presentation of the steps of a process or tasks necessary to
complete a project with special emphasis on the time taken for these activities
Procedure
1 List all the tasks or activities needed to be accomplished before the process of the
project
2 Decide which steps are undertaken in series and which steps can be run in parallel
Arrange the
Activities in a proper sequence
3 Prepare lsquoEvent Nodesrsquo at the completion of steps and number them
4 Write the description of the step and decide the time required for completing each
step
5 Calculate the earliest time to reach an event node for the start of the process
7 Ager the time for all event nodes including the completion of the process or the
project is available one calculates the latest time by which an event node must be
reached
Application
The diagram is also useful in planning and scheduling steps in complicated processes
especially in planning and scheduling projects which involve a large number of
activities
Example
31
1 Identify the tasks Eg 123hellip15
2 Know the time each task needs
3 Determine which tasks can be run in parallel and in normal sequences
4 Draw the sequence diagram and find the critical path
5 Calculate the project duration
6 Calculate the earliest starting time (or the earliest finishing time of last task) and the
latest finishing time
of each task(the latest starting time for the following task)
7 Mark the time indication
32
33
4) Process Decision Program Chart (PDPC)
Def The process decision program chart (PDPC) method helps us select the best
processes to obtain optimum results by evaluating the progress of events and various
conceivable outcomes
Description
The process decision program chart (PDPC) method is used to define the solution
process when dealing with problems that have more than one possible outcome [t
anticipates the unexpected Outcomes at each stage and plans for it
PDPC has two following patterns
Pattern I ndash In this pattern process starts with initial condition lsquoArsquo and proceeds to the
desired final condition lsquoZrsquo in an organized manner
Pattern 11- In this pattern first the final conditionrsquosrsquo is set Then the process from lsquoZrsquo
to the initial point lsquoArsquo is developed with the inclusion of various alternatives from
many points of view
Procedure
Discuss the issues related to the project among a cross-functional team
Discuss which issues must be examined and identify those issues
Consider and note down all the anticipated results for the identified issues
Weigh the feasibility of each solution proposed and investigate alternate
solutions
Classify each issue according to its urgency number of operations required
likelihood of Occurrence and difficulty
Consider the anticipated results and alternative solutions related to issues that
must be addressed immediately and link the items with arrows to the desired
goal
34
Prioritize the different issues and consider them all together Information
related to one set of
Possibilities could influence another set Related items shall be linked with a
broken line
If the department that will handle a process involving several lines is
determined circle
the process and write the name of the department within
Set a target date for completion
Have regular meetings to check progress in terms of the original PDPC
35
36
37
38
5) Matrix diagram
Purpose1) Explore the existence and the extent of relations between individual items in 2 sets
of factors or features and characteristics and express them in a symbolic form that is
easy to understand
2) Mostly used to understand the relations between the customer expectations as
expressed by the customers and product characteristics as designed manufactured and
tested by the manufacturer
Procedures1 Determine 2 sets of factors for which the relations are needed to be established
2 Divide the features and characteristics into primary secondary and tertiary
characteristics
3 Place the features vertically on the leg side of the matrix and characteristics
horizontally on top of the matrix
4 Enter the importance of the features on the column ager that for the tertiary
features10485775 In the main body of the matrix use the symbols to represent the degree of
connections between the feature and characteristics
6 Choose and define relationship symbols Most commonly used symbols are as
given below
Strong relationship=
Relationship =
Likely relationship=
Application
bull Matrix diagram can be used to solve problems by arranging data in such a way that
the relations between relevant factors are brought into sharp focus
bull There is no limit to the use of the tool
39
bull The most important application of matrix diagram is in clarifying relations between
individual features of customer requirements and individual product characteristics
Example 1
Matrix Diagram for Quality Functions and Responsibilities
40
41
6) Matrix Data Analysis Diagram1048577
Purpose
To present numerical data about two sets of factors in a matrix form and
analyze it to get numerical output
Can be applied in understanding the products and products characteristics
Procedure1048577
1 Decide the two factors whose relations are to be analyzed
2 Check the number of individual items in the two factors
3 Prepare a matrix to accommodate all the items of the two factors
4 Enter numerical data in the matrix
5 Give the diagram a suitable title
Example
42
43
44
7) Relationship diagram
This diagram clarifies the interrelations in a complex situation involving many
interrelated factors and serves to clarify the cause and effect relationships among
factors
Description
Relations diagram is defined as a technique used to solve problems that have complex
cause and effect relationships among a number of problems and factors that influence
them
Format
A special feature of relation diagram is its unrestricted Format However general
formats are as given below
1) Centrally converging relations diagram
The major item or problem to be solved is located in the center and the related factors
are arranged around the item or problem in such a way as to indicate close
relationships
2) Directionally intensive relations diagram
The major item or problem to be solved is located on one side of the diagram and the
various factors arranged in accordance with the flow of their major cause-and-effect
relationships on the other side
3) Relationship indication relations diagram
There are no restrictions on this format because the main point is to arrange the cause-
and-effect Relationships of the application items or factors so that they are expressed
in a straightforward manner in a Diagram
45
Procedure
1) Define the issueproblem in such a way that it is clearly understood and agreed on
by team members
2) Assemble the cross-functional team
3) Layout all the ideasissue cards that have been brought from other tools
4) Look for causeinfluence relationships between all ideas and draw relationship
arrows
a) Choose any of the ideas as a starting point and work through them in sequence
b)An outgoing arrow from an idea indicates that it is the stronger cause or influence
c) Draw only one way relationship arrows in the direction of the stronger cause or
Influence Make a decision on the stronger direction Do not draw two headed arrows
5) Review and revise the relationsrsquo diagram
6) Tally the number of outgoing and incoming arrows and select key items for further
planning
-record and clearly mark next to each issue the number of arrows going in and out of
it
-find the items with the highest number outgoing arrows and the items with the
highest number of incoming arrows
-a high number of outgoing arrows indicate that the item is a root cause and should be
tackle first
46
-a high number of incoming arrows indicate that the item is a key outcome and may
become a focus for planning either as a meaningful measure of overall success or as a
redefinition of the original issue under discussion
Example
47
48
Conclusions
Statististical QC is chiefly concerned in making sure that several procedures
and working arrangements are in place to provide for effective and efficient
statistical processes to minimize the risk of errors or weaknesses in
procedures or systems or in source material
Seven QC tools are most helpful in troubleshooting issues related to quality
All processes are affected by multiple factors and therefore statistical QC tools
can be applied to any process
The continuous use of these tools upgrades the personnel characteristics of the
people involved It enhances their ability to think generate ideas solve
problem and do proper planning
49
References asqorglearn-about-qualityseven-basic-quality-toolsoverviewhtml
httpsenwikipediaorgwikiSeven_Basic_Tools_of_Quality
wwwijergsorgfilesdocumentsAPPLICATION-45pd
httpssrcalionsciencecompdfQualityToolspdf
www3haorghkqehwiserdoc7bqtpdf
wwwmathmunca~variyathNew7QCToolspd
50
- 1 DEFINITION of Quality Control
- 3 Competitiveness
- 4 Customer Loyalty
- 5 Reputation
- 6 Compliance
- 7 Costs
- Benefits of Using Quality Control in Manufacturing
-
Now starting with 1st quality control tools
1) Pareto chart or Pareto diagram
A Pareto chart is a bar graph The lengths of the bars represent frequency or cost (time
or money) and are arranged with longest bars on the left and the shortest to the right
In this way the chart visually depicts which situations are more significant
When to Use a Pareto Chart
When analyzing data about the frequency of problems or causes in a process
When there are many problems or causes and you want to focus on the most
significant
When analyzing broad causes by looking at their specific components
When communicating with others about your data
Pareto Chart Procedure
Decide what categories you will use to group items
Decide what measurement is appropriate Common measurements are
frequency quantity cost and time
Decide what period of time the Pareto chart will cover One work cycle One
full day A week
Collect the data recording the category each time (Or assemble data that
already exist)
Subtotal the measurements for each category
Determine the appropriate scale for the measurements you have collected The
maximum value will be the largest subtotal from step 5 (If you will do
optional steps 8 and 9 below the maximum value will be the sum of all
subtotals from step 5) Mark the scale on the left side of the chart
6
Construct and label bars for each category Place the tallest at the far left then
the next tallest to its right and so on If there are many categories with small
measurements they can be grouped as ldquootherrdquo
Steps 8 and 9 are optional but are useful for analysis and communication
Calculate the percentage for each category the subtotal for that category
divided by the total for all categories Draw a right vertical axis and label it
with percentages Be sure the two scales match For example the left
measurement that corresponds to one-half should be exactly opposite 50 on
the right scale
Calculate and draw cumulative sums Add the subtotals for the first and
second categories and place a dot above the second bar indicating that sum
To that sum add the subtotal for the third category and place a dot above the
third bar for that new sum Continue the process for all the bars Connect the
dots starting at the top of the first bar The last dot should reach 100 percent
on the right scale
Pareto Chart Examples
Example 1 shows how many customer complaints were received in each of five
categories
Example 2 takes the largest category ldquodocumentsrdquo from Example 1 breaks it
down into six categories of document-related complaints and shows cumulative
values
If all complaints cause equal distress to the customer working on eliminating
document-related complaints would have the most impact and of those working on
quality certificates should be most fruitful
7
8
2) The fishbone diagram
A Cause-and Effect Diagram also known as fish bone diagram is a tool that shows
systematic relationship between a result or a symptom or an effect and its possible
causes It is an effective tool to systematically generate ideas about causes for
problems and to present these in a structured form This tool was devised by Dr
Kouro Ishikawa and as mentioned earlier is also known as Ishikawa Diagram
Procedure
The steps in the procedure to prepare a cause-and-effect diagram are
1 Agree on the definition of the Effect for which causes are to be found Place the
effect in the dark box at the right Draw the spine or the backbone as a dark line
leading to the box for the effect
1 Determine the main groups or categories of causes Place them in boxes and
connect them through large bones to the backbone
2 Brainstorm to find possible causes and subsidiary causes under each of the main
groups Make sure that the route from the cause to the effect is correctly depicted The
path must start from a root cause and end in the effect
3 After completing all the main groups brainstorm for more causes that may have
escaped earlier
4 Once the diagram is complete discuss relative importance of the causes Short list
the important root causes
9
10
3) Check sheets
Also called defect concentration diagram A check sheet is a structured prepared
form for collecting and analyzing data This is a generic tool that can be adapted for a
wide variety of purposes
When to Use a Check Sheet
When data can be observed and collected repeatedly by the same person or at
the same location
When collecting data on the frequency or patterns of events problems
defects defect location defect causes etc
When collecting data from a production process
Check Sheet Procedure
Decide what event or problem will be observed Develop operational
definitions
Decide when data will be collected and for how long
Design the form Set it up so that data can be recorded simply by making
check marks or Xs or similar symbols and so that data do not have to be
recopied for analysis
Label all spaces on the form
Test the check sheet for a short trial period to be sure it collects the
appropriate data and is easy to use
Each time the targeted event or problem occurs record data on the check
sheet
Check Sheet Example
The figure below shows a check sheet used to collect data on telephone interruptions
The tick marks were added as data was collected over several weeks
11
12
4) Control chart
The control chart is a graph used to study how a process changes over time Data are
plotted in time order A control chart always has a central line for the average an
upper line for the upper control limit and a lower line for the lower control limit
These lines are determined from historical data By comparing current data to these
lines you can draw conclusions about whether the process variation is consistent (in
control) or is unpredictable (out of control affected by special causes of variation)
Control charts for variable data are used in pairs The top chart monitors the average
or the centring of the distribution of data from the process The bottom chart monitors
the range or the width of the distribution If your data were shots in target practice
the average is where the shots are clustering and the range is how tightly they are
clustered Control charts for attribute data are used singly
41 When to Use a Control Chart
When controlling ongoing processes by finding and correcting problems as they
occur
When predicting the expected range of outcomes from a process
When determining whether a process is stable (in statistical control)
When analyzing patterns of process variation from special causes (non-routine
events) or common causes (built into the process)
When determining whether your quality improvement project should aim to
prevent specific problems or to make fundamental changes to the process
Control Chart Basic Procedure
Choose the appropriate control chart for your data
Determine the appropriate time period for collecting and plotting data
13
Collect data construct your chart and analyze the data
Look for ldquoout-of-control signalsrdquo on the control chart When one is identified mark it
on the chart and investigate the cause Document how you investigated what you
learned the cause and how it was corrected
Out-of-control signals
A single point outside the control limits In Figure 1 point sixteen is above the UCL
(upper control limit)
Two out of three successive points are on the same side of the centreline and farther
than 2 σ from it In Figure 1 point 4 sends that signal
Four out of five successive points are on the same side of the centreline and farther
than 1 σ from it In Figure 1 point 11 sends that signal
A run of eight in a row are on the same side of the centreline Or 10 out of 11 12 out
of 14 or 16 out of 20 In Figure 1 point 21 is eighth in a row above the centreline
Obvious consistent or persistent patterns that suggest something unusual about your
data and your process
5 Continue to plot data as they are generated As each new data point is plotted
check for new out-of-control signals
14
6 When you start a new control chart the process may be out of control If so the
control limits calculated from the first 20 points are conditional limits When you
have at least 20 sequential points from a period when the process is operating in
control recalculate control limits
5) Histogram chart
A frequency distribution shows how often each different value in a set of data occurs
A histogram is the most commonly used graph to show frequency distributions It
looks very much like a bar chart but there are important differences between them
When to Use a Histogram
When the data are numerical
When you want to see the shape of the datarsquos distribution especially when
determining whether the output of a process is distributed approximately
normally
When analyzing whether a process can meet the customerrsquos requirements
When analyzing what the output from a supplierrsquos process looks like
When seeing whether a process change has occurred from one time period to
another
When determining whether the outputs of two or more processes are different
When you wish to communicate the distribution of data quickly and easily to
others
Histogram Construction
Collect at least 50 consecutive data points from a process
Use the histogram worksheet to set up the histogram It will help you determine the
number of bars the range of numbers that go into each bar and the labels for the bar
edges After calculating W in step 2 of the worksheet use your judgment to adjust it
to a convenient number For example you might decide to round 09 to an even 10
15
The value for W must not have more decimal places than the numbers you will be
graphing
Draw x- and y-axes on graph paper Mark and label the y-axis for counting data
values Mark and label the x-axis with the L values from the worksheet The spaces
between these numbers will be the bars of the histogram Do not allow for spaces
between bars
For each data point mark off one count above the appropriate bar with an X or by
shading that portion of the bar
Histogram Analysis
Before drawing any conclusions from your histogram satisfy yourself that the process
was operating normally during the time period being studied If any unusual events
affected the process during the time period of the histogram your analysis of the
histogram shape probably cannot be generalized to all time periods
Analyze the meaning of your histogramrsquo
16
17
6) Scatter chart
The scatter diagram graphs pairs of numerical data with one variable on each axis to
look for a relationship between them If the variables are correlated the points will
fall along a line or curve The better the correlation the tighter the points will hug the
line
When to Use a Scatter Diagram
When you have paired numerical data
When your dependent variable may have multiple values for each value of your
independent variable
When trying to determine whether the two variables are related such ashellip
When trying to identify potential root causes of problems
After brainstorming causes and effects using a fishbone diagram to determine
objectively whether a particular cause and effect are related
When determining whether two effects that appears to be related both occur with the
same cause
When testing for autocorrelation before constructing a control chart
Scatter Diagram Procedure
Collect pairs of data where a relationship is suspected
Draw a graph with the independent variable on the horizontal axis and the dependent
variable on the vertical axis For each pair of data put a dot or a symbol where the x-
axis value intersects the y-axis value (If two dots fall together put them side by side
touching so that you can see both)
18
Look at the pattern of points to see if a relationship is obvious If the data clearly form
a line or a curve you may stop The variables are correlated You may wish to use
regression or correlation analysis now Otherwise complete steps 4 through 7
Divide points on the graph into four quadrants If there are X points on the graph
Count X2 points from top to bottom and draw a horizontal line
Count X2 points from left to right and draw a vertical line
If number of points is odd draw the line through the middle point
Count the points in each quadrant Do not count points on a line
Add the diagonally opposite quadrants Find the smaller sum and the total of points in
all quadrants
A = points in upper left + points in lower right
B = points in upper right + points in lower left
Q = the smaller of A and B
N = A + B
Look up the limit for N on the trend test table
If Q is less than the limit the two variables are related
If Q is greater than or equal to the limit the pattern could have occurred from random
chance
19
Scatter Diagram Example
The ZZ-400 manufacturing team suspects a relationship between product purity
(percent purity) and the amount of iron (measured in parts per million or ppm) Purity
and iron are plotted against each other as a scatter diagram as shown in the figure
below
There are 24 data points Median lines are drawn so that 12 points fall on each side for
both percent purity and ppm iron
To test for a relationship they calculate
A = points in upper left + points in lower right = 9 + 9 = 18
B = points in upper right + points in lower left = 3 + 3 = 6
Q = the smaller of A and B = the smaller of 18 and 6 = 6
N = A + B = 18 + 6 = 24
20
Then they look up the limit for N on the trend test table For N = 24 the limit is 6
Q is equal to the limit Therefore the pattern could have occurred from random
chance and no relationship is demonstrated
Scatter Diagram Example
Scatter Diagram Considerations
Here are some examples of situations in which might you use a scatter diagram
Variable A is the temperature of a reaction after 15 minutes Variable B measures the
colour of the product You suspect higher temperature makes the product darker Plot
temperature and colour on a scatter diagram
Variable A is the number of employees trained on new software and variable B is the
number of calls to the computer helps line You suspect that more training reduces the
number of calls Plot number of people trained versus number of calls
To test for autocorrelation of a measurement being monitored on a control chart plot
this pair of variables Variable A is the measurement at a given time Variable B is the
same measurement but at the previous time If the scatter diagram shows correlation
do another diagram where variable B is the measurement two times previously Keep
increasing the separation between the two times until the scatter diagram shows no
correlation
21
Even if the scatter diagram shows a relationship do not assume that one variable
caused the other Both may be influenced by a third variable
When the data are plotted the more the diagram resembles a straight line the stronger
the relationship
If a line is not clear statistics (N and Q) determine whether there is reasonable
certainty that a relationship exists If the statistics say that no relationship exists the
pattern could have occurred by random chance
If the scatter diagram shows no relationship between the variables consider whether
the data might be stratified
If the diagram shows no relationship consider whether the independent (x-axis)
variable has been varied widely Sometimes a relationship is not apparent because the
data donrsquot cover a wide enough range
Think creatively about how to use scatter diagrams to discover a root cause
Drawing a scatter diagram is the first step in looking for a relationship between
variables
22
7) Stratification
Stratification is a technique used in combination with other data analysis tools When
data from a variety of sources or categories have been lumped together the meaning
of the data can be impossible to see This technique separates the data so that patterns
can be seen
When to Use Stratification
Before collecting data
When data come from several sources or conditions such as shifts days of the
week suppliers or population groups
When data analysis may require separating different sources or conditions
Stratification Procedure
Before collecting data consider which information about the sources of the data
might have an effect on the results Set up the data collection so that you collect that
information as well
When plotting or graphing the collected data on a scatter diagram control chart
histogram or other analysis tool use different marks or colours to distinguish data
from various sources Data that are distinguished in this way are said to be
ldquostratifiedrdquo
Analyze the subsets of stratified data separately For example on a scatter diagram
where data are stratified into data from source 1 and data from source 2 draw
quadrants count points and determine the critical value only for the data from source
1 then only for the data from source 2
Stratification Example
23
The ZZndash400 manufacturing team drew a scatter diagram to test whether product
purity and iron contamination were related but the plot did not demonstrate a
relationship Then a team member realized that the data came from three different
reactors The team member redrew the diagram using a different symbol for each
reactorrsquos data
Now patterns can be seen The data from reactor 2 and reactor 3 are circled Even
without doing any calculations it is clear that for those two reactors purity decreases
as iron increases However the data from reactor 1 the solid dots that are not circled
do not show that relationship Something is different about reactor 1
Stratification Considerations
Here are examples of different sources that might require data to be stratified
Equipment
Shifts
Departments
24
Materials
Suppliers
Day of the week
Time of day
Products
Survey data usually benefit from stratification
Always consider before collecting data whether stratification might be needed during
analysis Plan to collect stratification information After the data are collected it might
be too late
On your graph or chart include a legend that identifies the marks or colours used
25
Now starting with new 7 quality control tool
Need of new quality control tool
Many customer requirements cannot always be adequately expressed by numerical
data alone Nevertheless even verbal statements can be expressions of facts because
it represents facts we ought to use Verbal data as well as numerical data in
controlling the managing quality It provides both quality control as well as
improvement during the manufacturing process
Benefits of new 7 quality control tool
Combine verbal with Numerical data
Looking for root cause
Clarify prioritize goals and schedule
Involve everyone into full cooperation and generate new ideas 1048577
The first new quality control tool is
1) Affinity Diagram
Application
An affinity diagram is used to organize into groupings large number of ideas opinions
or concerns about a Particular topic
Description
When a large number of ideas opinions or other concerns about a particular topic are
being collected this tool organizes the information into grouping~~based on the
natural relationships that exist among them The process is designed to stimulate
creativity and full participation It works best in groups of limited Size (a maximum
26
of eight members is recommended) in which members are accustomed to working
together This tool is often used to organize ideas generated by brainstorming
Procedure
State the topic to be studied in broad terms(details may prejudice the
response)
Record as many individual ideas opinions or concerns as possible on cards
(one per
card)
Mix the cards and spread them randomly on a large table
Group related cards together as follows
a)sort cards that seem to be related into groups and
b) limit number of grouping to ten without forcing single cards into groups
Locate or create a header card that captures the meaning of each group
Place this header card on top
Transfer the information from cards onto paper organized by groupings
Example For next generation digital camera we can organize the customer
Complains and requirements in an Affinity Diagram1048577
27
Affinity diagram
28
2) Tree diagram
Application
A tree diagram is used to show the interrelation between a topic and its component
elements
Description
A tree diagram systematically breaks down a topic into its component elements Ideas
generated by
Brainstorming and graphed or clustered with an affinity diagram can be converted
into a tree diagram
to show logical and sequential links This tool can be used in planning and problem
solving
Procedure
State the topic to be studied clearly
Define the major categories of the topic(brainstorm or use the header cards
from the affinity diagram)
Construct the diagram by placing the topic in a box on the left-hand side
Branch the major categories laterally to the right
For each major category define the component elements and sub-elements if
any
Laterally branch to the right the component elements and sub-elements for
each major category and
Review the diagram to ensure that there are no gaps in either sequence or
logic
29
30
3) Arrow diagram
Purpose To create a visual presentation of the steps of a process or tasks necessary to
complete a project with special emphasis on the time taken for these activities
Procedure
1 List all the tasks or activities needed to be accomplished before the process of the
project
2 Decide which steps are undertaken in series and which steps can be run in parallel
Arrange the
Activities in a proper sequence
3 Prepare lsquoEvent Nodesrsquo at the completion of steps and number them
4 Write the description of the step and decide the time required for completing each
step
5 Calculate the earliest time to reach an event node for the start of the process
7 Ager the time for all event nodes including the completion of the process or the
project is available one calculates the latest time by which an event node must be
reached
Application
The diagram is also useful in planning and scheduling steps in complicated processes
especially in planning and scheduling projects which involve a large number of
activities
Example
31
1 Identify the tasks Eg 123hellip15
2 Know the time each task needs
3 Determine which tasks can be run in parallel and in normal sequences
4 Draw the sequence diagram and find the critical path
5 Calculate the project duration
6 Calculate the earliest starting time (or the earliest finishing time of last task) and the
latest finishing time
of each task(the latest starting time for the following task)
7 Mark the time indication
32
33
4) Process Decision Program Chart (PDPC)
Def The process decision program chart (PDPC) method helps us select the best
processes to obtain optimum results by evaluating the progress of events and various
conceivable outcomes
Description
The process decision program chart (PDPC) method is used to define the solution
process when dealing with problems that have more than one possible outcome [t
anticipates the unexpected Outcomes at each stage and plans for it
PDPC has two following patterns
Pattern I ndash In this pattern process starts with initial condition lsquoArsquo and proceeds to the
desired final condition lsquoZrsquo in an organized manner
Pattern 11- In this pattern first the final conditionrsquosrsquo is set Then the process from lsquoZrsquo
to the initial point lsquoArsquo is developed with the inclusion of various alternatives from
many points of view
Procedure
Discuss the issues related to the project among a cross-functional team
Discuss which issues must be examined and identify those issues
Consider and note down all the anticipated results for the identified issues
Weigh the feasibility of each solution proposed and investigate alternate
solutions
Classify each issue according to its urgency number of operations required
likelihood of Occurrence and difficulty
Consider the anticipated results and alternative solutions related to issues that
must be addressed immediately and link the items with arrows to the desired
goal
34
Prioritize the different issues and consider them all together Information
related to one set of
Possibilities could influence another set Related items shall be linked with a
broken line
If the department that will handle a process involving several lines is
determined circle
the process and write the name of the department within
Set a target date for completion
Have regular meetings to check progress in terms of the original PDPC
35
36
37
38
5) Matrix diagram
Purpose1) Explore the existence and the extent of relations between individual items in 2 sets
of factors or features and characteristics and express them in a symbolic form that is
easy to understand
2) Mostly used to understand the relations between the customer expectations as
expressed by the customers and product characteristics as designed manufactured and
tested by the manufacturer
Procedures1 Determine 2 sets of factors for which the relations are needed to be established
2 Divide the features and characteristics into primary secondary and tertiary
characteristics
3 Place the features vertically on the leg side of the matrix and characteristics
horizontally on top of the matrix
4 Enter the importance of the features on the column ager that for the tertiary
features10485775 In the main body of the matrix use the symbols to represent the degree of
connections between the feature and characteristics
6 Choose and define relationship symbols Most commonly used symbols are as
given below
Strong relationship=
Relationship =
Likely relationship=
Application
bull Matrix diagram can be used to solve problems by arranging data in such a way that
the relations between relevant factors are brought into sharp focus
bull There is no limit to the use of the tool
39
bull The most important application of matrix diagram is in clarifying relations between
individual features of customer requirements and individual product characteristics
Example 1
Matrix Diagram for Quality Functions and Responsibilities
40
41
6) Matrix Data Analysis Diagram1048577
Purpose
To present numerical data about two sets of factors in a matrix form and
analyze it to get numerical output
Can be applied in understanding the products and products characteristics
Procedure1048577
1 Decide the two factors whose relations are to be analyzed
2 Check the number of individual items in the two factors
3 Prepare a matrix to accommodate all the items of the two factors
4 Enter numerical data in the matrix
5 Give the diagram a suitable title
Example
42
43
44
7) Relationship diagram
This diagram clarifies the interrelations in a complex situation involving many
interrelated factors and serves to clarify the cause and effect relationships among
factors
Description
Relations diagram is defined as a technique used to solve problems that have complex
cause and effect relationships among a number of problems and factors that influence
them
Format
A special feature of relation diagram is its unrestricted Format However general
formats are as given below
1) Centrally converging relations diagram
The major item or problem to be solved is located in the center and the related factors
are arranged around the item or problem in such a way as to indicate close
relationships
2) Directionally intensive relations diagram
The major item or problem to be solved is located on one side of the diagram and the
various factors arranged in accordance with the flow of their major cause-and-effect
relationships on the other side
3) Relationship indication relations diagram
There are no restrictions on this format because the main point is to arrange the cause-
and-effect Relationships of the application items or factors so that they are expressed
in a straightforward manner in a Diagram
45
Procedure
1) Define the issueproblem in such a way that it is clearly understood and agreed on
by team members
2) Assemble the cross-functional team
3) Layout all the ideasissue cards that have been brought from other tools
4) Look for causeinfluence relationships between all ideas and draw relationship
arrows
a) Choose any of the ideas as a starting point and work through them in sequence
b)An outgoing arrow from an idea indicates that it is the stronger cause or influence
c) Draw only one way relationship arrows in the direction of the stronger cause or
Influence Make a decision on the stronger direction Do not draw two headed arrows
5) Review and revise the relationsrsquo diagram
6) Tally the number of outgoing and incoming arrows and select key items for further
planning
-record and clearly mark next to each issue the number of arrows going in and out of
it
-find the items with the highest number outgoing arrows and the items with the
highest number of incoming arrows
-a high number of outgoing arrows indicate that the item is a root cause and should be
tackle first
46
-a high number of incoming arrows indicate that the item is a key outcome and may
become a focus for planning either as a meaningful measure of overall success or as a
redefinition of the original issue under discussion
Example
47
48
Conclusions
Statististical QC is chiefly concerned in making sure that several procedures
and working arrangements are in place to provide for effective and efficient
statistical processes to minimize the risk of errors or weaknesses in
procedures or systems or in source material
Seven QC tools are most helpful in troubleshooting issues related to quality
All processes are affected by multiple factors and therefore statistical QC tools
can be applied to any process
The continuous use of these tools upgrades the personnel characteristics of the
people involved It enhances their ability to think generate ideas solve
problem and do proper planning
49
References asqorglearn-about-qualityseven-basic-quality-toolsoverviewhtml
httpsenwikipediaorgwikiSeven_Basic_Tools_of_Quality
wwwijergsorgfilesdocumentsAPPLICATION-45pd
httpssrcalionsciencecompdfQualityToolspdf
www3haorghkqehwiserdoc7bqtpdf
wwwmathmunca~variyathNew7QCToolspd
50
- 1 DEFINITION of Quality Control
- 3 Competitiveness
- 4 Customer Loyalty
- 5 Reputation
- 6 Compliance
- 7 Costs
- Benefits of Using Quality Control in Manufacturing
-
Construct and label bars for each category Place the tallest at the far left then
the next tallest to its right and so on If there are many categories with small
measurements they can be grouped as ldquootherrdquo
Steps 8 and 9 are optional but are useful for analysis and communication
Calculate the percentage for each category the subtotal for that category
divided by the total for all categories Draw a right vertical axis and label it
with percentages Be sure the two scales match For example the left
measurement that corresponds to one-half should be exactly opposite 50 on
the right scale
Calculate and draw cumulative sums Add the subtotals for the first and
second categories and place a dot above the second bar indicating that sum
To that sum add the subtotal for the third category and place a dot above the
third bar for that new sum Continue the process for all the bars Connect the
dots starting at the top of the first bar The last dot should reach 100 percent
on the right scale
Pareto Chart Examples
Example 1 shows how many customer complaints were received in each of five
categories
Example 2 takes the largest category ldquodocumentsrdquo from Example 1 breaks it
down into six categories of document-related complaints and shows cumulative
values
If all complaints cause equal distress to the customer working on eliminating
document-related complaints would have the most impact and of those working on
quality certificates should be most fruitful
7
8
2) The fishbone diagram
A Cause-and Effect Diagram also known as fish bone diagram is a tool that shows
systematic relationship between a result or a symptom or an effect and its possible
causes It is an effective tool to systematically generate ideas about causes for
problems and to present these in a structured form This tool was devised by Dr
Kouro Ishikawa and as mentioned earlier is also known as Ishikawa Diagram
Procedure
The steps in the procedure to prepare a cause-and-effect diagram are
1 Agree on the definition of the Effect for which causes are to be found Place the
effect in the dark box at the right Draw the spine or the backbone as a dark line
leading to the box for the effect
1 Determine the main groups or categories of causes Place them in boxes and
connect them through large bones to the backbone
2 Brainstorm to find possible causes and subsidiary causes under each of the main
groups Make sure that the route from the cause to the effect is correctly depicted The
path must start from a root cause and end in the effect
3 After completing all the main groups brainstorm for more causes that may have
escaped earlier
4 Once the diagram is complete discuss relative importance of the causes Short list
the important root causes
9
10
3) Check sheets
Also called defect concentration diagram A check sheet is a structured prepared
form for collecting and analyzing data This is a generic tool that can be adapted for a
wide variety of purposes
When to Use a Check Sheet
When data can be observed and collected repeatedly by the same person or at
the same location
When collecting data on the frequency or patterns of events problems
defects defect location defect causes etc
When collecting data from a production process
Check Sheet Procedure
Decide what event or problem will be observed Develop operational
definitions
Decide when data will be collected and for how long
Design the form Set it up so that data can be recorded simply by making
check marks or Xs or similar symbols and so that data do not have to be
recopied for analysis
Label all spaces on the form
Test the check sheet for a short trial period to be sure it collects the
appropriate data and is easy to use
Each time the targeted event or problem occurs record data on the check
sheet
Check Sheet Example
The figure below shows a check sheet used to collect data on telephone interruptions
The tick marks were added as data was collected over several weeks
11
12
4) Control chart
The control chart is a graph used to study how a process changes over time Data are
plotted in time order A control chart always has a central line for the average an
upper line for the upper control limit and a lower line for the lower control limit
These lines are determined from historical data By comparing current data to these
lines you can draw conclusions about whether the process variation is consistent (in
control) or is unpredictable (out of control affected by special causes of variation)
Control charts for variable data are used in pairs The top chart monitors the average
or the centring of the distribution of data from the process The bottom chart monitors
the range or the width of the distribution If your data were shots in target practice
the average is where the shots are clustering and the range is how tightly they are
clustered Control charts for attribute data are used singly
41 When to Use a Control Chart
When controlling ongoing processes by finding and correcting problems as they
occur
When predicting the expected range of outcomes from a process
When determining whether a process is stable (in statistical control)
When analyzing patterns of process variation from special causes (non-routine
events) or common causes (built into the process)
When determining whether your quality improvement project should aim to
prevent specific problems or to make fundamental changes to the process
Control Chart Basic Procedure
Choose the appropriate control chart for your data
Determine the appropriate time period for collecting and plotting data
13
Collect data construct your chart and analyze the data
Look for ldquoout-of-control signalsrdquo on the control chart When one is identified mark it
on the chart and investigate the cause Document how you investigated what you
learned the cause and how it was corrected
Out-of-control signals
A single point outside the control limits In Figure 1 point sixteen is above the UCL
(upper control limit)
Two out of three successive points are on the same side of the centreline and farther
than 2 σ from it In Figure 1 point 4 sends that signal
Four out of five successive points are on the same side of the centreline and farther
than 1 σ from it In Figure 1 point 11 sends that signal
A run of eight in a row are on the same side of the centreline Or 10 out of 11 12 out
of 14 or 16 out of 20 In Figure 1 point 21 is eighth in a row above the centreline
Obvious consistent or persistent patterns that suggest something unusual about your
data and your process
5 Continue to plot data as they are generated As each new data point is plotted
check for new out-of-control signals
14
6 When you start a new control chart the process may be out of control If so the
control limits calculated from the first 20 points are conditional limits When you
have at least 20 sequential points from a period when the process is operating in
control recalculate control limits
5) Histogram chart
A frequency distribution shows how often each different value in a set of data occurs
A histogram is the most commonly used graph to show frequency distributions It
looks very much like a bar chart but there are important differences between them
When to Use a Histogram
When the data are numerical
When you want to see the shape of the datarsquos distribution especially when
determining whether the output of a process is distributed approximately
normally
When analyzing whether a process can meet the customerrsquos requirements
When analyzing what the output from a supplierrsquos process looks like
When seeing whether a process change has occurred from one time period to
another
When determining whether the outputs of two or more processes are different
When you wish to communicate the distribution of data quickly and easily to
others
Histogram Construction
Collect at least 50 consecutive data points from a process
Use the histogram worksheet to set up the histogram It will help you determine the
number of bars the range of numbers that go into each bar and the labels for the bar
edges After calculating W in step 2 of the worksheet use your judgment to adjust it
to a convenient number For example you might decide to round 09 to an even 10
15
The value for W must not have more decimal places than the numbers you will be
graphing
Draw x- and y-axes on graph paper Mark and label the y-axis for counting data
values Mark and label the x-axis with the L values from the worksheet The spaces
between these numbers will be the bars of the histogram Do not allow for spaces
between bars
For each data point mark off one count above the appropriate bar with an X or by
shading that portion of the bar
Histogram Analysis
Before drawing any conclusions from your histogram satisfy yourself that the process
was operating normally during the time period being studied If any unusual events
affected the process during the time period of the histogram your analysis of the
histogram shape probably cannot be generalized to all time periods
Analyze the meaning of your histogramrsquo
16
17
6) Scatter chart
The scatter diagram graphs pairs of numerical data with one variable on each axis to
look for a relationship between them If the variables are correlated the points will
fall along a line or curve The better the correlation the tighter the points will hug the
line
When to Use a Scatter Diagram
When you have paired numerical data
When your dependent variable may have multiple values for each value of your
independent variable
When trying to determine whether the two variables are related such ashellip
When trying to identify potential root causes of problems
After brainstorming causes and effects using a fishbone diagram to determine
objectively whether a particular cause and effect are related
When determining whether two effects that appears to be related both occur with the
same cause
When testing for autocorrelation before constructing a control chart
Scatter Diagram Procedure
Collect pairs of data where a relationship is suspected
Draw a graph with the independent variable on the horizontal axis and the dependent
variable on the vertical axis For each pair of data put a dot or a symbol where the x-
axis value intersects the y-axis value (If two dots fall together put them side by side
touching so that you can see both)
18
Look at the pattern of points to see if a relationship is obvious If the data clearly form
a line or a curve you may stop The variables are correlated You may wish to use
regression or correlation analysis now Otherwise complete steps 4 through 7
Divide points on the graph into four quadrants If there are X points on the graph
Count X2 points from top to bottom and draw a horizontal line
Count X2 points from left to right and draw a vertical line
If number of points is odd draw the line through the middle point
Count the points in each quadrant Do not count points on a line
Add the diagonally opposite quadrants Find the smaller sum and the total of points in
all quadrants
A = points in upper left + points in lower right
B = points in upper right + points in lower left
Q = the smaller of A and B
N = A + B
Look up the limit for N on the trend test table
If Q is less than the limit the two variables are related
If Q is greater than or equal to the limit the pattern could have occurred from random
chance
19
Scatter Diagram Example
The ZZ-400 manufacturing team suspects a relationship between product purity
(percent purity) and the amount of iron (measured in parts per million or ppm) Purity
and iron are plotted against each other as a scatter diagram as shown in the figure
below
There are 24 data points Median lines are drawn so that 12 points fall on each side for
both percent purity and ppm iron
To test for a relationship they calculate
A = points in upper left + points in lower right = 9 + 9 = 18
B = points in upper right + points in lower left = 3 + 3 = 6
Q = the smaller of A and B = the smaller of 18 and 6 = 6
N = A + B = 18 + 6 = 24
20
Then they look up the limit for N on the trend test table For N = 24 the limit is 6
Q is equal to the limit Therefore the pattern could have occurred from random
chance and no relationship is demonstrated
Scatter Diagram Example
Scatter Diagram Considerations
Here are some examples of situations in which might you use a scatter diagram
Variable A is the temperature of a reaction after 15 minutes Variable B measures the
colour of the product You suspect higher temperature makes the product darker Plot
temperature and colour on a scatter diagram
Variable A is the number of employees trained on new software and variable B is the
number of calls to the computer helps line You suspect that more training reduces the
number of calls Plot number of people trained versus number of calls
To test for autocorrelation of a measurement being monitored on a control chart plot
this pair of variables Variable A is the measurement at a given time Variable B is the
same measurement but at the previous time If the scatter diagram shows correlation
do another diagram where variable B is the measurement two times previously Keep
increasing the separation between the two times until the scatter diagram shows no
correlation
21
Even if the scatter diagram shows a relationship do not assume that one variable
caused the other Both may be influenced by a third variable
When the data are plotted the more the diagram resembles a straight line the stronger
the relationship
If a line is not clear statistics (N and Q) determine whether there is reasonable
certainty that a relationship exists If the statistics say that no relationship exists the
pattern could have occurred by random chance
If the scatter diagram shows no relationship between the variables consider whether
the data might be stratified
If the diagram shows no relationship consider whether the independent (x-axis)
variable has been varied widely Sometimes a relationship is not apparent because the
data donrsquot cover a wide enough range
Think creatively about how to use scatter diagrams to discover a root cause
Drawing a scatter diagram is the first step in looking for a relationship between
variables
22
7) Stratification
Stratification is a technique used in combination with other data analysis tools When
data from a variety of sources or categories have been lumped together the meaning
of the data can be impossible to see This technique separates the data so that patterns
can be seen
When to Use Stratification
Before collecting data
When data come from several sources or conditions such as shifts days of the
week suppliers or population groups
When data analysis may require separating different sources or conditions
Stratification Procedure
Before collecting data consider which information about the sources of the data
might have an effect on the results Set up the data collection so that you collect that
information as well
When plotting or graphing the collected data on a scatter diagram control chart
histogram or other analysis tool use different marks or colours to distinguish data
from various sources Data that are distinguished in this way are said to be
ldquostratifiedrdquo
Analyze the subsets of stratified data separately For example on a scatter diagram
where data are stratified into data from source 1 and data from source 2 draw
quadrants count points and determine the critical value only for the data from source
1 then only for the data from source 2
Stratification Example
23
The ZZndash400 manufacturing team drew a scatter diagram to test whether product
purity and iron contamination were related but the plot did not demonstrate a
relationship Then a team member realized that the data came from three different
reactors The team member redrew the diagram using a different symbol for each
reactorrsquos data
Now patterns can be seen The data from reactor 2 and reactor 3 are circled Even
without doing any calculations it is clear that for those two reactors purity decreases
as iron increases However the data from reactor 1 the solid dots that are not circled
do not show that relationship Something is different about reactor 1
Stratification Considerations
Here are examples of different sources that might require data to be stratified
Equipment
Shifts
Departments
24
Materials
Suppliers
Day of the week
Time of day
Products
Survey data usually benefit from stratification
Always consider before collecting data whether stratification might be needed during
analysis Plan to collect stratification information After the data are collected it might
be too late
On your graph or chart include a legend that identifies the marks or colours used
25
Now starting with new 7 quality control tool
Need of new quality control tool
Many customer requirements cannot always be adequately expressed by numerical
data alone Nevertheless even verbal statements can be expressions of facts because
it represents facts we ought to use Verbal data as well as numerical data in
controlling the managing quality It provides both quality control as well as
improvement during the manufacturing process
Benefits of new 7 quality control tool
Combine verbal with Numerical data
Looking for root cause
Clarify prioritize goals and schedule
Involve everyone into full cooperation and generate new ideas 1048577
The first new quality control tool is
1) Affinity Diagram
Application
An affinity diagram is used to organize into groupings large number of ideas opinions
or concerns about a Particular topic
Description
When a large number of ideas opinions or other concerns about a particular topic are
being collected this tool organizes the information into grouping~~based on the
natural relationships that exist among them The process is designed to stimulate
creativity and full participation It works best in groups of limited Size (a maximum
26
of eight members is recommended) in which members are accustomed to working
together This tool is often used to organize ideas generated by brainstorming
Procedure
State the topic to be studied in broad terms(details may prejudice the
response)
Record as many individual ideas opinions or concerns as possible on cards
(one per
card)
Mix the cards and spread them randomly on a large table
Group related cards together as follows
a)sort cards that seem to be related into groups and
b) limit number of grouping to ten without forcing single cards into groups
Locate or create a header card that captures the meaning of each group
Place this header card on top
Transfer the information from cards onto paper organized by groupings
Example For next generation digital camera we can organize the customer
Complains and requirements in an Affinity Diagram1048577
27
Affinity diagram
28
2) Tree diagram
Application
A tree diagram is used to show the interrelation between a topic and its component
elements
Description
A tree diagram systematically breaks down a topic into its component elements Ideas
generated by
Brainstorming and graphed or clustered with an affinity diagram can be converted
into a tree diagram
to show logical and sequential links This tool can be used in planning and problem
solving
Procedure
State the topic to be studied clearly
Define the major categories of the topic(brainstorm or use the header cards
from the affinity diagram)
Construct the diagram by placing the topic in a box on the left-hand side
Branch the major categories laterally to the right
For each major category define the component elements and sub-elements if
any
Laterally branch to the right the component elements and sub-elements for
each major category and
Review the diagram to ensure that there are no gaps in either sequence or
logic
29
30
3) Arrow diagram
Purpose To create a visual presentation of the steps of a process or tasks necessary to
complete a project with special emphasis on the time taken for these activities
Procedure
1 List all the tasks or activities needed to be accomplished before the process of the
project
2 Decide which steps are undertaken in series and which steps can be run in parallel
Arrange the
Activities in a proper sequence
3 Prepare lsquoEvent Nodesrsquo at the completion of steps and number them
4 Write the description of the step and decide the time required for completing each
step
5 Calculate the earliest time to reach an event node for the start of the process
7 Ager the time for all event nodes including the completion of the process or the
project is available one calculates the latest time by which an event node must be
reached
Application
The diagram is also useful in planning and scheduling steps in complicated processes
especially in planning and scheduling projects which involve a large number of
activities
Example
31
1 Identify the tasks Eg 123hellip15
2 Know the time each task needs
3 Determine which tasks can be run in parallel and in normal sequences
4 Draw the sequence diagram and find the critical path
5 Calculate the project duration
6 Calculate the earliest starting time (or the earliest finishing time of last task) and the
latest finishing time
of each task(the latest starting time for the following task)
7 Mark the time indication
32
33
4) Process Decision Program Chart (PDPC)
Def The process decision program chart (PDPC) method helps us select the best
processes to obtain optimum results by evaluating the progress of events and various
conceivable outcomes
Description
The process decision program chart (PDPC) method is used to define the solution
process when dealing with problems that have more than one possible outcome [t
anticipates the unexpected Outcomes at each stage and plans for it
PDPC has two following patterns
Pattern I ndash In this pattern process starts with initial condition lsquoArsquo and proceeds to the
desired final condition lsquoZrsquo in an organized manner
Pattern 11- In this pattern first the final conditionrsquosrsquo is set Then the process from lsquoZrsquo
to the initial point lsquoArsquo is developed with the inclusion of various alternatives from
many points of view
Procedure
Discuss the issues related to the project among a cross-functional team
Discuss which issues must be examined and identify those issues
Consider and note down all the anticipated results for the identified issues
Weigh the feasibility of each solution proposed and investigate alternate
solutions
Classify each issue according to its urgency number of operations required
likelihood of Occurrence and difficulty
Consider the anticipated results and alternative solutions related to issues that
must be addressed immediately and link the items with arrows to the desired
goal
34
Prioritize the different issues and consider them all together Information
related to one set of
Possibilities could influence another set Related items shall be linked with a
broken line
If the department that will handle a process involving several lines is
determined circle
the process and write the name of the department within
Set a target date for completion
Have regular meetings to check progress in terms of the original PDPC
35
36
37
38
5) Matrix diagram
Purpose1) Explore the existence and the extent of relations between individual items in 2 sets
of factors or features and characteristics and express them in a symbolic form that is
easy to understand
2) Mostly used to understand the relations between the customer expectations as
expressed by the customers and product characteristics as designed manufactured and
tested by the manufacturer
Procedures1 Determine 2 sets of factors for which the relations are needed to be established
2 Divide the features and characteristics into primary secondary and tertiary
characteristics
3 Place the features vertically on the leg side of the matrix and characteristics
horizontally on top of the matrix
4 Enter the importance of the features on the column ager that for the tertiary
features10485775 In the main body of the matrix use the symbols to represent the degree of
connections between the feature and characteristics
6 Choose and define relationship symbols Most commonly used symbols are as
given below
Strong relationship=
Relationship =
Likely relationship=
Application
bull Matrix diagram can be used to solve problems by arranging data in such a way that
the relations between relevant factors are brought into sharp focus
bull There is no limit to the use of the tool
39
bull The most important application of matrix diagram is in clarifying relations between
individual features of customer requirements and individual product characteristics
Example 1
Matrix Diagram for Quality Functions and Responsibilities
40
41
6) Matrix Data Analysis Diagram1048577
Purpose
To present numerical data about two sets of factors in a matrix form and
analyze it to get numerical output
Can be applied in understanding the products and products characteristics
Procedure1048577
1 Decide the two factors whose relations are to be analyzed
2 Check the number of individual items in the two factors
3 Prepare a matrix to accommodate all the items of the two factors
4 Enter numerical data in the matrix
5 Give the diagram a suitable title
Example
42
43
44
7) Relationship diagram
This diagram clarifies the interrelations in a complex situation involving many
interrelated factors and serves to clarify the cause and effect relationships among
factors
Description
Relations diagram is defined as a technique used to solve problems that have complex
cause and effect relationships among a number of problems and factors that influence
them
Format
A special feature of relation diagram is its unrestricted Format However general
formats are as given below
1) Centrally converging relations diagram
The major item or problem to be solved is located in the center and the related factors
are arranged around the item or problem in such a way as to indicate close
relationships
2) Directionally intensive relations diagram
The major item or problem to be solved is located on one side of the diagram and the
various factors arranged in accordance with the flow of their major cause-and-effect
relationships on the other side
3) Relationship indication relations diagram
There are no restrictions on this format because the main point is to arrange the cause-
and-effect Relationships of the application items or factors so that they are expressed
in a straightforward manner in a Diagram
45
Procedure
1) Define the issueproblem in such a way that it is clearly understood and agreed on
by team members
2) Assemble the cross-functional team
3) Layout all the ideasissue cards that have been brought from other tools
4) Look for causeinfluence relationships between all ideas and draw relationship
arrows
a) Choose any of the ideas as a starting point and work through them in sequence
b)An outgoing arrow from an idea indicates that it is the stronger cause or influence
c) Draw only one way relationship arrows in the direction of the stronger cause or
Influence Make a decision on the stronger direction Do not draw two headed arrows
5) Review and revise the relationsrsquo diagram
6) Tally the number of outgoing and incoming arrows and select key items for further
planning
-record and clearly mark next to each issue the number of arrows going in and out of
it
-find the items with the highest number outgoing arrows and the items with the
highest number of incoming arrows
-a high number of outgoing arrows indicate that the item is a root cause and should be
tackle first
46
-a high number of incoming arrows indicate that the item is a key outcome and may
become a focus for planning either as a meaningful measure of overall success or as a
redefinition of the original issue under discussion
Example
47
48
Conclusions
Statististical QC is chiefly concerned in making sure that several procedures
and working arrangements are in place to provide for effective and efficient
statistical processes to minimize the risk of errors or weaknesses in
procedures or systems or in source material
Seven QC tools are most helpful in troubleshooting issues related to quality
All processes are affected by multiple factors and therefore statistical QC tools
can be applied to any process
The continuous use of these tools upgrades the personnel characteristics of the
people involved It enhances their ability to think generate ideas solve
problem and do proper planning
49
References asqorglearn-about-qualityseven-basic-quality-toolsoverviewhtml
httpsenwikipediaorgwikiSeven_Basic_Tools_of_Quality
wwwijergsorgfilesdocumentsAPPLICATION-45pd
httpssrcalionsciencecompdfQualityToolspdf
www3haorghkqehwiserdoc7bqtpdf
wwwmathmunca~variyathNew7QCToolspd
50
- 1 DEFINITION of Quality Control
- 3 Competitiveness
- 4 Customer Loyalty
- 5 Reputation
- 6 Compliance
- 7 Costs
- Benefits of Using Quality Control in Manufacturing
-
8
2) The fishbone diagram
A Cause-and Effect Diagram also known as fish bone diagram is a tool that shows
systematic relationship between a result or a symptom or an effect and its possible
causes It is an effective tool to systematically generate ideas about causes for
problems and to present these in a structured form This tool was devised by Dr
Kouro Ishikawa and as mentioned earlier is also known as Ishikawa Diagram
Procedure
The steps in the procedure to prepare a cause-and-effect diagram are
1 Agree on the definition of the Effect for which causes are to be found Place the
effect in the dark box at the right Draw the spine or the backbone as a dark line
leading to the box for the effect
1 Determine the main groups or categories of causes Place them in boxes and
connect them through large bones to the backbone
2 Brainstorm to find possible causes and subsidiary causes under each of the main
groups Make sure that the route from the cause to the effect is correctly depicted The
path must start from a root cause and end in the effect
3 After completing all the main groups brainstorm for more causes that may have
escaped earlier
4 Once the diagram is complete discuss relative importance of the causes Short list
the important root causes
9
10
3) Check sheets
Also called defect concentration diagram A check sheet is a structured prepared
form for collecting and analyzing data This is a generic tool that can be adapted for a
wide variety of purposes
When to Use a Check Sheet
When data can be observed and collected repeatedly by the same person or at
the same location
When collecting data on the frequency or patterns of events problems
defects defect location defect causes etc
When collecting data from a production process
Check Sheet Procedure
Decide what event or problem will be observed Develop operational
definitions
Decide when data will be collected and for how long
Design the form Set it up so that data can be recorded simply by making
check marks or Xs or similar symbols and so that data do not have to be
recopied for analysis
Label all spaces on the form
Test the check sheet for a short trial period to be sure it collects the
appropriate data and is easy to use
Each time the targeted event or problem occurs record data on the check
sheet
Check Sheet Example
The figure below shows a check sheet used to collect data on telephone interruptions
The tick marks were added as data was collected over several weeks
11
12
4) Control chart
The control chart is a graph used to study how a process changes over time Data are
plotted in time order A control chart always has a central line for the average an
upper line for the upper control limit and a lower line for the lower control limit
These lines are determined from historical data By comparing current data to these
lines you can draw conclusions about whether the process variation is consistent (in
control) or is unpredictable (out of control affected by special causes of variation)
Control charts for variable data are used in pairs The top chart monitors the average
or the centring of the distribution of data from the process The bottom chart monitors
the range or the width of the distribution If your data were shots in target practice
the average is where the shots are clustering and the range is how tightly they are
clustered Control charts for attribute data are used singly
41 When to Use a Control Chart
When controlling ongoing processes by finding and correcting problems as they
occur
When predicting the expected range of outcomes from a process
When determining whether a process is stable (in statistical control)
When analyzing patterns of process variation from special causes (non-routine
events) or common causes (built into the process)
When determining whether your quality improvement project should aim to
prevent specific problems or to make fundamental changes to the process
Control Chart Basic Procedure
Choose the appropriate control chart for your data
Determine the appropriate time period for collecting and plotting data
13
Collect data construct your chart and analyze the data
Look for ldquoout-of-control signalsrdquo on the control chart When one is identified mark it
on the chart and investigate the cause Document how you investigated what you
learned the cause and how it was corrected
Out-of-control signals
A single point outside the control limits In Figure 1 point sixteen is above the UCL
(upper control limit)
Two out of three successive points are on the same side of the centreline and farther
than 2 σ from it In Figure 1 point 4 sends that signal
Four out of five successive points are on the same side of the centreline and farther
than 1 σ from it In Figure 1 point 11 sends that signal
A run of eight in a row are on the same side of the centreline Or 10 out of 11 12 out
of 14 or 16 out of 20 In Figure 1 point 21 is eighth in a row above the centreline
Obvious consistent or persistent patterns that suggest something unusual about your
data and your process
5 Continue to plot data as they are generated As each new data point is plotted
check for new out-of-control signals
14
6 When you start a new control chart the process may be out of control If so the
control limits calculated from the first 20 points are conditional limits When you
have at least 20 sequential points from a period when the process is operating in
control recalculate control limits
5) Histogram chart
A frequency distribution shows how often each different value in a set of data occurs
A histogram is the most commonly used graph to show frequency distributions It
looks very much like a bar chart but there are important differences between them
When to Use a Histogram
When the data are numerical
When you want to see the shape of the datarsquos distribution especially when
determining whether the output of a process is distributed approximately
normally
When analyzing whether a process can meet the customerrsquos requirements
When analyzing what the output from a supplierrsquos process looks like
When seeing whether a process change has occurred from one time period to
another
When determining whether the outputs of two or more processes are different
When you wish to communicate the distribution of data quickly and easily to
others
Histogram Construction
Collect at least 50 consecutive data points from a process
Use the histogram worksheet to set up the histogram It will help you determine the
number of bars the range of numbers that go into each bar and the labels for the bar
edges After calculating W in step 2 of the worksheet use your judgment to adjust it
to a convenient number For example you might decide to round 09 to an even 10
15
The value for W must not have more decimal places than the numbers you will be
graphing
Draw x- and y-axes on graph paper Mark and label the y-axis for counting data
values Mark and label the x-axis with the L values from the worksheet The spaces
between these numbers will be the bars of the histogram Do not allow for spaces
between bars
For each data point mark off one count above the appropriate bar with an X or by
shading that portion of the bar
Histogram Analysis
Before drawing any conclusions from your histogram satisfy yourself that the process
was operating normally during the time period being studied If any unusual events
affected the process during the time period of the histogram your analysis of the
histogram shape probably cannot be generalized to all time periods
Analyze the meaning of your histogramrsquo
16
17
6) Scatter chart
The scatter diagram graphs pairs of numerical data with one variable on each axis to
look for a relationship between them If the variables are correlated the points will
fall along a line or curve The better the correlation the tighter the points will hug the
line
When to Use a Scatter Diagram
When you have paired numerical data
When your dependent variable may have multiple values for each value of your
independent variable
When trying to determine whether the two variables are related such ashellip
When trying to identify potential root causes of problems
After brainstorming causes and effects using a fishbone diagram to determine
objectively whether a particular cause and effect are related
When determining whether two effects that appears to be related both occur with the
same cause
When testing for autocorrelation before constructing a control chart
Scatter Diagram Procedure
Collect pairs of data where a relationship is suspected
Draw a graph with the independent variable on the horizontal axis and the dependent
variable on the vertical axis For each pair of data put a dot or a symbol where the x-
axis value intersects the y-axis value (If two dots fall together put them side by side
touching so that you can see both)
18
Look at the pattern of points to see if a relationship is obvious If the data clearly form
a line or a curve you may stop The variables are correlated You may wish to use
regression or correlation analysis now Otherwise complete steps 4 through 7
Divide points on the graph into four quadrants If there are X points on the graph
Count X2 points from top to bottom and draw a horizontal line
Count X2 points from left to right and draw a vertical line
If number of points is odd draw the line through the middle point
Count the points in each quadrant Do not count points on a line
Add the diagonally opposite quadrants Find the smaller sum and the total of points in
all quadrants
A = points in upper left + points in lower right
B = points in upper right + points in lower left
Q = the smaller of A and B
N = A + B
Look up the limit for N on the trend test table
If Q is less than the limit the two variables are related
If Q is greater than or equal to the limit the pattern could have occurred from random
chance
19
Scatter Diagram Example
The ZZ-400 manufacturing team suspects a relationship between product purity
(percent purity) and the amount of iron (measured in parts per million or ppm) Purity
and iron are plotted against each other as a scatter diagram as shown in the figure
below
There are 24 data points Median lines are drawn so that 12 points fall on each side for
both percent purity and ppm iron
To test for a relationship they calculate
A = points in upper left + points in lower right = 9 + 9 = 18
B = points in upper right + points in lower left = 3 + 3 = 6
Q = the smaller of A and B = the smaller of 18 and 6 = 6
N = A + B = 18 + 6 = 24
20
Then they look up the limit for N on the trend test table For N = 24 the limit is 6
Q is equal to the limit Therefore the pattern could have occurred from random
chance and no relationship is demonstrated
Scatter Diagram Example
Scatter Diagram Considerations
Here are some examples of situations in which might you use a scatter diagram
Variable A is the temperature of a reaction after 15 minutes Variable B measures the
colour of the product You suspect higher temperature makes the product darker Plot
temperature and colour on a scatter diagram
Variable A is the number of employees trained on new software and variable B is the
number of calls to the computer helps line You suspect that more training reduces the
number of calls Plot number of people trained versus number of calls
To test for autocorrelation of a measurement being monitored on a control chart plot
this pair of variables Variable A is the measurement at a given time Variable B is the
same measurement but at the previous time If the scatter diagram shows correlation
do another diagram where variable B is the measurement two times previously Keep
increasing the separation between the two times until the scatter diagram shows no
correlation
21
Even if the scatter diagram shows a relationship do not assume that one variable
caused the other Both may be influenced by a third variable
When the data are plotted the more the diagram resembles a straight line the stronger
the relationship
If a line is not clear statistics (N and Q) determine whether there is reasonable
certainty that a relationship exists If the statistics say that no relationship exists the
pattern could have occurred by random chance
If the scatter diagram shows no relationship between the variables consider whether
the data might be stratified
If the diagram shows no relationship consider whether the independent (x-axis)
variable has been varied widely Sometimes a relationship is not apparent because the
data donrsquot cover a wide enough range
Think creatively about how to use scatter diagrams to discover a root cause
Drawing a scatter diagram is the first step in looking for a relationship between
variables
22
7) Stratification
Stratification is a technique used in combination with other data analysis tools When
data from a variety of sources or categories have been lumped together the meaning
of the data can be impossible to see This technique separates the data so that patterns
can be seen
When to Use Stratification
Before collecting data
When data come from several sources or conditions such as shifts days of the
week suppliers or population groups
When data analysis may require separating different sources or conditions
Stratification Procedure
Before collecting data consider which information about the sources of the data
might have an effect on the results Set up the data collection so that you collect that
information as well
When plotting or graphing the collected data on a scatter diagram control chart
histogram or other analysis tool use different marks or colours to distinguish data
from various sources Data that are distinguished in this way are said to be
ldquostratifiedrdquo
Analyze the subsets of stratified data separately For example on a scatter diagram
where data are stratified into data from source 1 and data from source 2 draw
quadrants count points and determine the critical value only for the data from source
1 then only for the data from source 2
Stratification Example
23
The ZZndash400 manufacturing team drew a scatter diagram to test whether product
purity and iron contamination were related but the plot did not demonstrate a
relationship Then a team member realized that the data came from three different
reactors The team member redrew the diagram using a different symbol for each
reactorrsquos data
Now patterns can be seen The data from reactor 2 and reactor 3 are circled Even
without doing any calculations it is clear that for those two reactors purity decreases
as iron increases However the data from reactor 1 the solid dots that are not circled
do not show that relationship Something is different about reactor 1
Stratification Considerations
Here are examples of different sources that might require data to be stratified
Equipment
Shifts
Departments
24
Materials
Suppliers
Day of the week
Time of day
Products
Survey data usually benefit from stratification
Always consider before collecting data whether stratification might be needed during
analysis Plan to collect stratification information After the data are collected it might
be too late
On your graph or chart include a legend that identifies the marks or colours used
25
Now starting with new 7 quality control tool
Need of new quality control tool
Many customer requirements cannot always be adequately expressed by numerical
data alone Nevertheless even verbal statements can be expressions of facts because
it represents facts we ought to use Verbal data as well as numerical data in
controlling the managing quality It provides both quality control as well as
improvement during the manufacturing process
Benefits of new 7 quality control tool
Combine verbal with Numerical data
Looking for root cause
Clarify prioritize goals and schedule
Involve everyone into full cooperation and generate new ideas 1048577
The first new quality control tool is
1) Affinity Diagram
Application
An affinity diagram is used to organize into groupings large number of ideas opinions
or concerns about a Particular topic
Description
When a large number of ideas opinions or other concerns about a particular topic are
being collected this tool organizes the information into grouping~~based on the
natural relationships that exist among them The process is designed to stimulate
creativity and full participation It works best in groups of limited Size (a maximum
26
of eight members is recommended) in which members are accustomed to working
together This tool is often used to organize ideas generated by brainstorming
Procedure
State the topic to be studied in broad terms(details may prejudice the
response)
Record as many individual ideas opinions or concerns as possible on cards
(one per
card)
Mix the cards and spread them randomly on a large table
Group related cards together as follows
a)sort cards that seem to be related into groups and
b) limit number of grouping to ten without forcing single cards into groups
Locate or create a header card that captures the meaning of each group
Place this header card on top
Transfer the information from cards onto paper organized by groupings
Example For next generation digital camera we can organize the customer
Complains and requirements in an Affinity Diagram1048577
27
Affinity diagram
28
2) Tree diagram
Application
A tree diagram is used to show the interrelation between a topic and its component
elements
Description
A tree diagram systematically breaks down a topic into its component elements Ideas
generated by
Brainstorming and graphed or clustered with an affinity diagram can be converted
into a tree diagram
to show logical and sequential links This tool can be used in planning and problem
solving
Procedure
State the topic to be studied clearly
Define the major categories of the topic(brainstorm or use the header cards
from the affinity diagram)
Construct the diagram by placing the topic in a box on the left-hand side
Branch the major categories laterally to the right
For each major category define the component elements and sub-elements if
any
Laterally branch to the right the component elements and sub-elements for
each major category and
Review the diagram to ensure that there are no gaps in either sequence or
logic
29
30
3) Arrow diagram
Purpose To create a visual presentation of the steps of a process or tasks necessary to
complete a project with special emphasis on the time taken for these activities
Procedure
1 List all the tasks or activities needed to be accomplished before the process of the
project
2 Decide which steps are undertaken in series and which steps can be run in parallel
Arrange the
Activities in a proper sequence
3 Prepare lsquoEvent Nodesrsquo at the completion of steps and number them
4 Write the description of the step and decide the time required for completing each
step
5 Calculate the earliest time to reach an event node for the start of the process
7 Ager the time for all event nodes including the completion of the process or the
project is available one calculates the latest time by which an event node must be
reached
Application
The diagram is also useful in planning and scheduling steps in complicated processes
especially in planning and scheduling projects which involve a large number of
activities
Example
31
1 Identify the tasks Eg 123hellip15
2 Know the time each task needs
3 Determine which tasks can be run in parallel and in normal sequences
4 Draw the sequence diagram and find the critical path
5 Calculate the project duration
6 Calculate the earliest starting time (or the earliest finishing time of last task) and the
latest finishing time
of each task(the latest starting time for the following task)
7 Mark the time indication
32
33
4) Process Decision Program Chart (PDPC)
Def The process decision program chart (PDPC) method helps us select the best
processes to obtain optimum results by evaluating the progress of events and various
conceivable outcomes
Description
The process decision program chart (PDPC) method is used to define the solution
process when dealing with problems that have more than one possible outcome [t
anticipates the unexpected Outcomes at each stage and plans for it
PDPC has two following patterns
Pattern I ndash In this pattern process starts with initial condition lsquoArsquo and proceeds to the
desired final condition lsquoZrsquo in an organized manner
Pattern 11- In this pattern first the final conditionrsquosrsquo is set Then the process from lsquoZrsquo
to the initial point lsquoArsquo is developed with the inclusion of various alternatives from
many points of view
Procedure
Discuss the issues related to the project among a cross-functional team
Discuss which issues must be examined and identify those issues
Consider and note down all the anticipated results for the identified issues
Weigh the feasibility of each solution proposed and investigate alternate
solutions
Classify each issue according to its urgency number of operations required
likelihood of Occurrence and difficulty
Consider the anticipated results and alternative solutions related to issues that
must be addressed immediately and link the items with arrows to the desired
goal
34
Prioritize the different issues and consider them all together Information
related to one set of
Possibilities could influence another set Related items shall be linked with a
broken line
If the department that will handle a process involving several lines is
determined circle
the process and write the name of the department within
Set a target date for completion
Have regular meetings to check progress in terms of the original PDPC
35
36
37
38
5) Matrix diagram
Purpose1) Explore the existence and the extent of relations between individual items in 2 sets
of factors or features and characteristics and express them in a symbolic form that is
easy to understand
2) Mostly used to understand the relations between the customer expectations as
expressed by the customers and product characteristics as designed manufactured and
tested by the manufacturer
Procedures1 Determine 2 sets of factors for which the relations are needed to be established
2 Divide the features and characteristics into primary secondary and tertiary
characteristics
3 Place the features vertically on the leg side of the matrix and characteristics
horizontally on top of the matrix
4 Enter the importance of the features on the column ager that for the tertiary
features10485775 In the main body of the matrix use the symbols to represent the degree of
connections between the feature and characteristics
6 Choose and define relationship symbols Most commonly used symbols are as
given below
Strong relationship=
Relationship =
Likely relationship=
Application
bull Matrix diagram can be used to solve problems by arranging data in such a way that
the relations between relevant factors are brought into sharp focus
bull There is no limit to the use of the tool
39
bull The most important application of matrix diagram is in clarifying relations between
individual features of customer requirements and individual product characteristics
Example 1
Matrix Diagram for Quality Functions and Responsibilities
40
41
6) Matrix Data Analysis Diagram1048577
Purpose
To present numerical data about two sets of factors in a matrix form and
analyze it to get numerical output
Can be applied in understanding the products and products characteristics
Procedure1048577
1 Decide the two factors whose relations are to be analyzed
2 Check the number of individual items in the two factors
3 Prepare a matrix to accommodate all the items of the two factors
4 Enter numerical data in the matrix
5 Give the diagram a suitable title
Example
42
43
44
7) Relationship diagram
This diagram clarifies the interrelations in a complex situation involving many
interrelated factors and serves to clarify the cause and effect relationships among
factors
Description
Relations diagram is defined as a technique used to solve problems that have complex
cause and effect relationships among a number of problems and factors that influence
them
Format
A special feature of relation diagram is its unrestricted Format However general
formats are as given below
1) Centrally converging relations diagram
The major item or problem to be solved is located in the center and the related factors
are arranged around the item or problem in such a way as to indicate close
relationships
2) Directionally intensive relations diagram
The major item or problem to be solved is located on one side of the diagram and the
various factors arranged in accordance with the flow of their major cause-and-effect
relationships on the other side
3) Relationship indication relations diagram
There are no restrictions on this format because the main point is to arrange the cause-
and-effect Relationships of the application items or factors so that they are expressed
in a straightforward manner in a Diagram
45
Procedure
1) Define the issueproblem in such a way that it is clearly understood and agreed on
by team members
2) Assemble the cross-functional team
3) Layout all the ideasissue cards that have been brought from other tools
4) Look for causeinfluence relationships between all ideas and draw relationship
arrows
a) Choose any of the ideas as a starting point and work through them in sequence
b)An outgoing arrow from an idea indicates that it is the stronger cause or influence
c) Draw only one way relationship arrows in the direction of the stronger cause or
Influence Make a decision on the stronger direction Do not draw two headed arrows
5) Review and revise the relationsrsquo diagram
6) Tally the number of outgoing and incoming arrows and select key items for further
planning
-record and clearly mark next to each issue the number of arrows going in and out of
it
-find the items with the highest number outgoing arrows and the items with the
highest number of incoming arrows
-a high number of outgoing arrows indicate that the item is a root cause and should be
tackle first
46
-a high number of incoming arrows indicate that the item is a key outcome and may
become a focus for planning either as a meaningful measure of overall success or as a
redefinition of the original issue under discussion
Example
47
48
Conclusions
Statististical QC is chiefly concerned in making sure that several procedures
and working arrangements are in place to provide for effective and efficient
statistical processes to minimize the risk of errors or weaknesses in
procedures or systems or in source material
Seven QC tools are most helpful in troubleshooting issues related to quality
All processes are affected by multiple factors and therefore statistical QC tools
can be applied to any process
The continuous use of these tools upgrades the personnel characteristics of the
people involved It enhances their ability to think generate ideas solve
problem and do proper planning
49
References asqorglearn-about-qualityseven-basic-quality-toolsoverviewhtml
httpsenwikipediaorgwikiSeven_Basic_Tools_of_Quality
wwwijergsorgfilesdocumentsAPPLICATION-45pd
httpssrcalionsciencecompdfQualityToolspdf
www3haorghkqehwiserdoc7bqtpdf
wwwmathmunca~variyathNew7QCToolspd
50
- 1 DEFINITION of Quality Control
- 3 Competitiveness
- 4 Customer Loyalty
- 5 Reputation
- 6 Compliance
- 7 Costs
- Benefits of Using Quality Control in Manufacturing
-
2) The fishbone diagram
A Cause-and Effect Diagram also known as fish bone diagram is a tool that shows
systematic relationship between a result or a symptom or an effect and its possible
causes It is an effective tool to systematically generate ideas about causes for
problems and to present these in a structured form This tool was devised by Dr
Kouro Ishikawa and as mentioned earlier is also known as Ishikawa Diagram
Procedure
The steps in the procedure to prepare a cause-and-effect diagram are
1 Agree on the definition of the Effect for which causes are to be found Place the
effect in the dark box at the right Draw the spine or the backbone as a dark line
leading to the box for the effect
1 Determine the main groups or categories of causes Place them in boxes and
connect them through large bones to the backbone
2 Brainstorm to find possible causes and subsidiary causes under each of the main
groups Make sure that the route from the cause to the effect is correctly depicted The
path must start from a root cause and end in the effect
3 After completing all the main groups brainstorm for more causes that may have
escaped earlier
4 Once the diagram is complete discuss relative importance of the causes Short list
the important root causes
9
10
3) Check sheets
Also called defect concentration diagram A check sheet is a structured prepared
form for collecting and analyzing data This is a generic tool that can be adapted for a
wide variety of purposes
When to Use a Check Sheet
When data can be observed and collected repeatedly by the same person or at
the same location
When collecting data on the frequency or patterns of events problems
defects defect location defect causes etc
When collecting data from a production process
Check Sheet Procedure
Decide what event or problem will be observed Develop operational
definitions
Decide when data will be collected and for how long
Design the form Set it up so that data can be recorded simply by making
check marks or Xs or similar symbols and so that data do not have to be
recopied for analysis
Label all spaces on the form
Test the check sheet for a short trial period to be sure it collects the
appropriate data and is easy to use
Each time the targeted event or problem occurs record data on the check
sheet
Check Sheet Example
The figure below shows a check sheet used to collect data on telephone interruptions
The tick marks were added as data was collected over several weeks
11
12
4) Control chart
The control chart is a graph used to study how a process changes over time Data are
plotted in time order A control chart always has a central line for the average an
upper line for the upper control limit and a lower line for the lower control limit
These lines are determined from historical data By comparing current data to these
lines you can draw conclusions about whether the process variation is consistent (in
control) or is unpredictable (out of control affected by special causes of variation)
Control charts for variable data are used in pairs The top chart monitors the average
or the centring of the distribution of data from the process The bottom chart monitors
the range or the width of the distribution If your data were shots in target practice
the average is where the shots are clustering and the range is how tightly they are
clustered Control charts for attribute data are used singly
41 When to Use a Control Chart
When controlling ongoing processes by finding and correcting problems as they
occur
When predicting the expected range of outcomes from a process
When determining whether a process is stable (in statistical control)
When analyzing patterns of process variation from special causes (non-routine
events) or common causes (built into the process)
When determining whether your quality improvement project should aim to
prevent specific problems or to make fundamental changes to the process
Control Chart Basic Procedure
Choose the appropriate control chart for your data
Determine the appropriate time period for collecting and plotting data
13
Collect data construct your chart and analyze the data
Look for ldquoout-of-control signalsrdquo on the control chart When one is identified mark it
on the chart and investigate the cause Document how you investigated what you
learned the cause and how it was corrected
Out-of-control signals
A single point outside the control limits In Figure 1 point sixteen is above the UCL
(upper control limit)
Two out of three successive points are on the same side of the centreline and farther
than 2 σ from it In Figure 1 point 4 sends that signal
Four out of five successive points are on the same side of the centreline and farther
than 1 σ from it In Figure 1 point 11 sends that signal
A run of eight in a row are on the same side of the centreline Or 10 out of 11 12 out
of 14 or 16 out of 20 In Figure 1 point 21 is eighth in a row above the centreline
Obvious consistent or persistent patterns that suggest something unusual about your
data and your process
5 Continue to plot data as they are generated As each new data point is plotted
check for new out-of-control signals
14
6 When you start a new control chart the process may be out of control If so the
control limits calculated from the first 20 points are conditional limits When you
have at least 20 sequential points from a period when the process is operating in
control recalculate control limits
5) Histogram chart
A frequency distribution shows how often each different value in a set of data occurs
A histogram is the most commonly used graph to show frequency distributions It
looks very much like a bar chart but there are important differences between them
When to Use a Histogram
When the data are numerical
When you want to see the shape of the datarsquos distribution especially when
determining whether the output of a process is distributed approximately
normally
When analyzing whether a process can meet the customerrsquos requirements
When analyzing what the output from a supplierrsquos process looks like
When seeing whether a process change has occurred from one time period to
another
When determining whether the outputs of two or more processes are different
When you wish to communicate the distribution of data quickly and easily to
others
Histogram Construction
Collect at least 50 consecutive data points from a process
Use the histogram worksheet to set up the histogram It will help you determine the
number of bars the range of numbers that go into each bar and the labels for the bar
edges After calculating W in step 2 of the worksheet use your judgment to adjust it
to a convenient number For example you might decide to round 09 to an even 10
15
The value for W must not have more decimal places than the numbers you will be
graphing
Draw x- and y-axes on graph paper Mark and label the y-axis for counting data
values Mark and label the x-axis with the L values from the worksheet The spaces
between these numbers will be the bars of the histogram Do not allow for spaces
between bars
For each data point mark off one count above the appropriate bar with an X or by
shading that portion of the bar
Histogram Analysis
Before drawing any conclusions from your histogram satisfy yourself that the process
was operating normally during the time period being studied If any unusual events
affected the process during the time period of the histogram your analysis of the
histogram shape probably cannot be generalized to all time periods
Analyze the meaning of your histogramrsquo
16
17
6) Scatter chart
The scatter diagram graphs pairs of numerical data with one variable on each axis to
look for a relationship between them If the variables are correlated the points will
fall along a line or curve The better the correlation the tighter the points will hug the
line
When to Use a Scatter Diagram
When you have paired numerical data
When your dependent variable may have multiple values for each value of your
independent variable
When trying to determine whether the two variables are related such ashellip
When trying to identify potential root causes of problems
After brainstorming causes and effects using a fishbone diagram to determine
objectively whether a particular cause and effect are related
When determining whether two effects that appears to be related both occur with the
same cause
When testing for autocorrelation before constructing a control chart
Scatter Diagram Procedure
Collect pairs of data where a relationship is suspected
Draw a graph with the independent variable on the horizontal axis and the dependent
variable on the vertical axis For each pair of data put a dot or a symbol where the x-
axis value intersects the y-axis value (If two dots fall together put them side by side
touching so that you can see both)
18
Look at the pattern of points to see if a relationship is obvious If the data clearly form
a line or a curve you may stop The variables are correlated You may wish to use
regression or correlation analysis now Otherwise complete steps 4 through 7
Divide points on the graph into four quadrants If there are X points on the graph
Count X2 points from top to bottom and draw a horizontal line
Count X2 points from left to right and draw a vertical line
If number of points is odd draw the line through the middle point
Count the points in each quadrant Do not count points on a line
Add the diagonally opposite quadrants Find the smaller sum and the total of points in
all quadrants
A = points in upper left + points in lower right
B = points in upper right + points in lower left
Q = the smaller of A and B
N = A + B
Look up the limit for N on the trend test table
If Q is less than the limit the two variables are related
If Q is greater than or equal to the limit the pattern could have occurred from random
chance
19
Scatter Diagram Example
The ZZ-400 manufacturing team suspects a relationship between product purity
(percent purity) and the amount of iron (measured in parts per million or ppm) Purity
and iron are plotted against each other as a scatter diagram as shown in the figure
below
There are 24 data points Median lines are drawn so that 12 points fall on each side for
both percent purity and ppm iron
To test for a relationship they calculate
A = points in upper left + points in lower right = 9 + 9 = 18
B = points in upper right + points in lower left = 3 + 3 = 6
Q = the smaller of A and B = the smaller of 18 and 6 = 6
N = A + B = 18 + 6 = 24
20
Then they look up the limit for N on the trend test table For N = 24 the limit is 6
Q is equal to the limit Therefore the pattern could have occurred from random
chance and no relationship is demonstrated
Scatter Diagram Example
Scatter Diagram Considerations
Here are some examples of situations in which might you use a scatter diagram
Variable A is the temperature of a reaction after 15 minutes Variable B measures the
colour of the product You suspect higher temperature makes the product darker Plot
temperature and colour on a scatter diagram
Variable A is the number of employees trained on new software and variable B is the
number of calls to the computer helps line You suspect that more training reduces the
number of calls Plot number of people trained versus number of calls
To test for autocorrelation of a measurement being monitored on a control chart plot
this pair of variables Variable A is the measurement at a given time Variable B is the
same measurement but at the previous time If the scatter diagram shows correlation
do another diagram where variable B is the measurement two times previously Keep
increasing the separation between the two times until the scatter diagram shows no
correlation
21
Even if the scatter diagram shows a relationship do not assume that one variable
caused the other Both may be influenced by a third variable
When the data are plotted the more the diagram resembles a straight line the stronger
the relationship
If a line is not clear statistics (N and Q) determine whether there is reasonable
certainty that a relationship exists If the statistics say that no relationship exists the
pattern could have occurred by random chance
If the scatter diagram shows no relationship between the variables consider whether
the data might be stratified
If the diagram shows no relationship consider whether the independent (x-axis)
variable has been varied widely Sometimes a relationship is not apparent because the
data donrsquot cover a wide enough range
Think creatively about how to use scatter diagrams to discover a root cause
Drawing a scatter diagram is the first step in looking for a relationship between
variables
22
7) Stratification
Stratification is a technique used in combination with other data analysis tools When
data from a variety of sources or categories have been lumped together the meaning
of the data can be impossible to see This technique separates the data so that patterns
can be seen
When to Use Stratification
Before collecting data
When data come from several sources or conditions such as shifts days of the
week suppliers or population groups
When data analysis may require separating different sources or conditions
Stratification Procedure
Before collecting data consider which information about the sources of the data
might have an effect on the results Set up the data collection so that you collect that
information as well
When plotting or graphing the collected data on a scatter diagram control chart
histogram or other analysis tool use different marks or colours to distinguish data
from various sources Data that are distinguished in this way are said to be
ldquostratifiedrdquo
Analyze the subsets of stratified data separately For example on a scatter diagram
where data are stratified into data from source 1 and data from source 2 draw
quadrants count points and determine the critical value only for the data from source
1 then only for the data from source 2
Stratification Example
23
The ZZndash400 manufacturing team drew a scatter diagram to test whether product
purity and iron contamination were related but the plot did not demonstrate a
relationship Then a team member realized that the data came from three different
reactors The team member redrew the diagram using a different symbol for each
reactorrsquos data
Now patterns can be seen The data from reactor 2 and reactor 3 are circled Even
without doing any calculations it is clear that for those two reactors purity decreases
as iron increases However the data from reactor 1 the solid dots that are not circled
do not show that relationship Something is different about reactor 1
Stratification Considerations
Here are examples of different sources that might require data to be stratified
Equipment
Shifts
Departments
24
Materials
Suppliers
Day of the week
Time of day
Products
Survey data usually benefit from stratification
Always consider before collecting data whether stratification might be needed during
analysis Plan to collect stratification information After the data are collected it might
be too late
On your graph or chart include a legend that identifies the marks or colours used
25
Now starting with new 7 quality control tool
Need of new quality control tool
Many customer requirements cannot always be adequately expressed by numerical
data alone Nevertheless even verbal statements can be expressions of facts because
it represents facts we ought to use Verbal data as well as numerical data in
controlling the managing quality It provides both quality control as well as
improvement during the manufacturing process
Benefits of new 7 quality control tool
Combine verbal with Numerical data
Looking for root cause
Clarify prioritize goals and schedule
Involve everyone into full cooperation and generate new ideas 1048577
The first new quality control tool is
1) Affinity Diagram
Application
An affinity diagram is used to organize into groupings large number of ideas opinions
or concerns about a Particular topic
Description
When a large number of ideas opinions or other concerns about a particular topic are
being collected this tool organizes the information into grouping~~based on the
natural relationships that exist among them The process is designed to stimulate
creativity and full participation It works best in groups of limited Size (a maximum
26
of eight members is recommended) in which members are accustomed to working
together This tool is often used to organize ideas generated by brainstorming
Procedure
State the topic to be studied in broad terms(details may prejudice the
response)
Record as many individual ideas opinions or concerns as possible on cards
(one per
card)
Mix the cards and spread them randomly on a large table
Group related cards together as follows
a)sort cards that seem to be related into groups and
b) limit number of grouping to ten without forcing single cards into groups
Locate or create a header card that captures the meaning of each group
Place this header card on top
Transfer the information from cards onto paper organized by groupings
Example For next generation digital camera we can organize the customer
Complains and requirements in an Affinity Diagram1048577
27
Affinity diagram
28
2) Tree diagram
Application
A tree diagram is used to show the interrelation between a topic and its component
elements
Description
A tree diagram systematically breaks down a topic into its component elements Ideas
generated by
Brainstorming and graphed or clustered with an affinity diagram can be converted
into a tree diagram
to show logical and sequential links This tool can be used in planning and problem
solving
Procedure
State the topic to be studied clearly
Define the major categories of the topic(brainstorm or use the header cards
from the affinity diagram)
Construct the diagram by placing the topic in a box on the left-hand side
Branch the major categories laterally to the right
For each major category define the component elements and sub-elements if
any
Laterally branch to the right the component elements and sub-elements for
each major category and
Review the diagram to ensure that there are no gaps in either sequence or
logic
29
30
3) Arrow diagram
Purpose To create a visual presentation of the steps of a process or tasks necessary to
complete a project with special emphasis on the time taken for these activities
Procedure
1 List all the tasks or activities needed to be accomplished before the process of the
project
2 Decide which steps are undertaken in series and which steps can be run in parallel
Arrange the
Activities in a proper sequence
3 Prepare lsquoEvent Nodesrsquo at the completion of steps and number them
4 Write the description of the step and decide the time required for completing each
step
5 Calculate the earliest time to reach an event node for the start of the process
7 Ager the time for all event nodes including the completion of the process or the
project is available one calculates the latest time by which an event node must be
reached
Application
The diagram is also useful in planning and scheduling steps in complicated processes
especially in planning and scheduling projects which involve a large number of
activities
Example
31
1 Identify the tasks Eg 123hellip15
2 Know the time each task needs
3 Determine which tasks can be run in parallel and in normal sequences
4 Draw the sequence diagram and find the critical path
5 Calculate the project duration
6 Calculate the earliest starting time (or the earliest finishing time of last task) and the
latest finishing time
of each task(the latest starting time for the following task)
7 Mark the time indication
32
33
4) Process Decision Program Chart (PDPC)
Def The process decision program chart (PDPC) method helps us select the best
processes to obtain optimum results by evaluating the progress of events and various
conceivable outcomes
Description
The process decision program chart (PDPC) method is used to define the solution
process when dealing with problems that have more than one possible outcome [t
anticipates the unexpected Outcomes at each stage and plans for it
PDPC has two following patterns
Pattern I ndash In this pattern process starts with initial condition lsquoArsquo and proceeds to the
desired final condition lsquoZrsquo in an organized manner
Pattern 11- In this pattern first the final conditionrsquosrsquo is set Then the process from lsquoZrsquo
to the initial point lsquoArsquo is developed with the inclusion of various alternatives from
many points of view
Procedure
Discuss the issues related to the project among a cross-functional team
Discuss which issues must be examined and identify those issues
Consider and note down all the anticipated results for the identified issues
Weigh the feasibility of each solution proposed and investigate alternate
solutions
Classify each issue according to its urgency number of operations required
likelihood of Occurrence and difficulty
Consider the anticipated results and alternative solutions related to issues that
must be addressed immediately and link the items with arrows to the desired
goal
34
Prioritize the different issues and consider them all together Information
related to one set of
Possibilities could influence another set Related items shall be linked with a
broken line
If the department that will handle a process involving several lines is
determined circle
the process and write the name of the department within
Set a target date for completion
Have regular meetings to check progress in terms of the original PDPC
35
36
37
38
5) Matrix diagram
Purpose1) Explore the existence and the extent of relations between individual items in 2 sets
of factors or features and characteristics and express them in a symbolic form that is
easy to understand
2) Mostly used to understand the relations between the customer expectations as
expressed by the customers and product characteristics as designed manufactured and
tested by the manufacturer
Procedures1 Determine 2 sets of factors for which the relations are needed to be established
2 Divide the features and characteristics into primary secondary and tertiary
characteristics
3 Place the features vertically on the leg side of the matrix and characteristics
horizontally on top of the matrix
4 Enter the importance of the features on the column ager that for the tertiary
features10485775 In the main body of the matrix use the symbols to represent the degree of
connections between the feature and characteristics
6 Choose and define relationship symbols Most commonly used symbols are as
given below
Strong relationship=
Relationship =
Likely relationship=
Application
bull Matrix diagram can be used to solve problems by arranging data in such a way that
the relations between relevant factors are brought into sharp focus
bull There is no limit to the use of the tool
39
bull The most important application of matrix diagram is in clarifying relations between
individual features of customer requirements and individual product characteristics
Example 1
Matrix Diagram for Quality Functions and Responsibilities
40
41
6) Matrix Data Analysis Diagram1048577
Purpose
To present numerical data about two sets of factors in a matrix form and
analyze it to get numerical output
Can be applied in understanding the products and products characteristics
Procedure1048577
1 Decide the two factors whose relations are to be analyzed
2 Check the number of individual items in the two factors
3 Prepare a matrix to accommodate all the items of the two factors
4 Enter numerical data in the matrix
5 Give the diagram a suitable title
Example
42
43
44
7) Relationship diagram
This diagram clarifies the interrelations in a complex situation involving many
interrelated factors and serves to clarify the cause and effect relationships among
factors
Description
Relations diagram is defined as a technique used to solve problems that have complex
cause and effect relationships among a number of problems and factors that influence
them
Format
A special feature of relation diagram is its unrestricted Format However general
formats are as given below
1) Centrally converging relations diagram
The major item or problem to be solved is located in the center and the related factors
are arranged around the item or problem in such a way as to indicate close
relationships
2) Directionally intensive relations diagram
The major item or problem to be solved is located on one side of the diagram and the
various factors arranged in accordance with the flow of their major cause-and-effect
relationships on the other side
3) Relationship indication relations diagram
There are no restrictions on this format because the main point is to arrange the cause-
and-effect Relationships of the application items or factors so that they are expressed
in a straightforward manner in a Diagram
45
Procedure
1) Define the issueproblem in such a way that it is clearly understood and agreed on
by team members
2) Assemble the cross-functional team
3) Layout all the ideasissue cards that have been brought from other tools
4) Look for causeinfluence relationships between all ideas and draw relationship
arrows
a) Choose any of the ideas as a starting point and work through them in sequence
b)An outgoing arrow from an idea indicates that it is the stronger cause or influence
c) Draw only one way relationship arrows in the direction of the stronger cause or
Influence Make a decision on the stronger direction Do not draw two headed arrows
5) Review and revise the relationsrsquo diagram
6) Tally the number of outgoing and incoming arrows and select key items for further
planning
-record and clearly mark next to each issue the number of arrows going in and out of
it
-find the items with the highest number outgoing arrows and the items with the
highest number of incoming arrows
-a high number of outgoing arrows indicate that the item is a root cause and should be
tackle first
46
-a high number of incoming arrows indicate that the item is a key outcome and may
become a focus for planning either as a meaningful measure of overall success or as a
redefinition of the original issue under discussion
Example
47
48
Conclusions
Statististical QC is chiefly concerned in making sure that several procedures
and working arrangements are in place to provide for effective and efficient
statistical processes to minimize the risk of errors or weaknesses in
procedures or systems or in source material
Seven QC tools are most helpful in troubleshooting issues related to quality
All processes are affected by multiple factors and therefore statistical QC tools
can be applied to any process
The continuous use of these tools upgrades the personnel characteristics of the
people involved It enhances their ability to think generate ideas solve
problem and do proper planning
49
References asqorglearn-about-qualityseven-basic-quality-toolsoverviewhtml
httpsenwikipediaorgwikiSeven_Basic_Tools_of_Quality
wwwijergsorgfilesdocumentsAPPLICATION-45pd
httpssrcalionsciencecompdfQualityToolspdf
www3haorghkqehwiserdoc7bqtpdf
wwwmathmunca~variyathNew7QCToolspd
50
- 1 DEFINITION of Quality Control
- 3 Competitiveness
- 4 Customer Loyalty
- 5 Reputation
- 6 Compliance
- 7 Costs
- Benefits of Using Quality Control in Manufacturing
-
10
3) Check sheets
Also called defect concentration diagram A check sheet is a structured prepared
form for collecting and analyzing data This is a generic tool that can be adapted for a
wide variety of purposes
When to Use a Check Sheet
When data can be observed and collected repeatedly by the same person or at
the same location
When collecting data on the frequency or patterns of events problems
defects defect location defect causes etc
When collecting data from a production process
Check Sheet Procedure
Decide what event or problem will be observed Develop operational
definitions
Decide when data will be collected and for how long
Design the form Set it up so that data can be recorded simply by making
check marks or Xs or similar symbols and so that data do not have to be
recopied for analysis
Label all spaces on the form
Test the check sheet for a short trial period to be sure it collects the
appropriate data and is easy to use
Each time the targeted event or problem occurs record data on the check
sheet
Check Sheet Example
The figure below shows a check sheet used to collect data on telephone interruptions
The tick marks were added as data was collected over several weeks
11
12
4) Control chart
The control chart is a graph used to study how a process changes over time Data are
plotted in time order A control chart always has a central line for the average an
upper line for the upper control limit and a lower line for the lower control limit
These lines are determined from historical data By comparing current data to these
lines you can draw conclusions about whether the process variation is consistent (in
control) or is unpredictable (out of control affected by special causes of variation)
Control charts for variable data are used in pairs The top chart monitors the average
or the centring of the distribution of data from the process The bottom chart monitors
the range or the width of the distribution If your data were shots in target practice
the average is where the shots are clustering and the range is how tightly they are
clustered Control charts for attribute data are used singly
41 When to Use a Control Chart
When controlling ongoing processes by finding and correcting problems as they
occur
When predicting the expected range of outcomes from a process
When determining whether a process is stable (in statistical control)
When analyzing patterns of process variation from special causes (non-routine
events) or common causes (built into the process)
When determining whether your quality improvement project should aim to
prevent specific problems or to make fundamental changes to the process
Control Chart Basic Procedure
Choose the appropriate control chart for your data
Determine the appropriate time period for collecting and plotting data
13
Collect data construct your chart and analyze the data
Look for ldquoout-of-control signalsrdquo on the control chart When one is identified mark it
on the chart and investigate the cause Document how you investigated what you
learned the cause and how it was corrected
Out-of-control signals
A single point outside the control limits In Figure 1 point sixteen is above the UCL
(upper control limit)
Two out of three successive points are on the same side of the centreline and farther
than 2 σ from it In Figure 1 point 4 sends that signal
Four out of five successive points are on the same side of the centreline and farther
than 1 σ from it In Figure 1 point 11 sends that signal
A run of eight in a row are on the same side of the centreline Or 10 out of 11 12 out
of 14 or 16 out of 20 In Figure 1 point 21 is eighth in a row above the centreline
Obvious consistent or persistent patterns that suggest something unusual about your
data and your process
5 Continue to plot data as they are generated As each new data point is plotted
check for new out-of-control signals
14
6 When you start a new control chart the process may be out of control If so the
control limits calculated from the first 20 points are conditional limits When you
have at least 20 sequential points from a period when the process is operating in
control recalculate control limits
5) Histogram chart
A frequency distribution shows how often each different value in a set of data occurs
A histogram is the most commonly used graph to show frequency distributions It
looks very much like a bar chart but there are important differences between them
When to Use a Histogram
When the data are numerical
When you want to see the shape of the datarsquos distribution especially when
determining whether the output of a process is distributed approximately
normally
When analyzing whether a process can meet the customerrsquos requirements
When analyzing what the output from a supplierrsquos process looks like
When seeing whether a process change has occurred from one time period to
another
When determining whether the outputs of two or more processes are different
When you wish to communicate the distribution of data quickly and easily to
others
Histogram Construction
Collect at least 50 consecutive data points from a process
Use the histogram worksheet to set up the histogram It will help you determine the
number of bars the range of numbers that go into each bar and the labels for the bar
edges After calculating W in step 2 of the worksheet use your judgment to adjust it
to a convenient number For example you might decide to round 09 to an even 10
15
The value for W must not have more decimal places than the numbers you will be
graphing
Draw x- and y-axes on graph paper Mark and label the y-axis for counting data
values Mark and label the x-axis with the L values from the worksheet The spaces
between these numbers will be the bars of the histogram Do not allow for spaces
between bars
For each data point mark off one count above the appropriate bar with an X or by
shading that portion of the bar
Histogram Analysis
Before drawing any conclusions from your histogram satisfy yourself that the process
was operating normally during the time period being studied If any unusual events
affected the process during the time period of the histogram your analysis of the
histogram shape probably cannot be generalized to all time periods
Analyze the meaning of your histogramrsquo
16
17
6) Scatter chart
The scatter diagram graphs pairs of numerical data with one variable on each axis to
look for a relationship between them If the variables are correlated the points will
fall along a line or curve The better the correlation the tighter the points will hug the
line
When to Use a Scatter Diagram
When you have paired numerical data
When your dependent variable may have multiple values for each value of your
independent variable
When trying to determine whether the two variables are related such ashellip
When trying to identify potential root causes of problems
After brainstorming causes and effects using a fishbone diagram to determine
objectively whether a particular cause and effect are related
When determining whether two effects that appears to be related both occur with the
same cause
When testing for autocorrelation before constructing a control chart
Scatter Diagram Procedure
Collect pairs of data where a relationship is suspected
Draw a graph with the independent variable on the horizontal axis and the dependent
variable on the vertical axis For each pair of data put a dot or a symbol where the x-
axis value intersects the y-axis value (If two dots fall together put them side by side
touching so that you can see both)
18
Look at the pattern of points to see if a relationship is obvious If the data clearly form
a line or a curve you may stop The variables are correlated You may wish to use
regression or correlation analysis now Otherwise complete steps 4 through 7
Divide points on the graph into four quadrants If there are X points on the graph
Count X2 points from top to bottom and draw a horizontal line
Count X2 points from left to right and draw a vertical line
If number of points is odd draw the line through the middle point
Count the points in each quadrant Do not count points on a line
Add the diagonally opposite quadrants Find the smaller sum and the total of points in
all quadrants
A = points in upper left + points in lower right
B = points in upper right + points in lower left
Q = the smaller of A and B
N = A + B
Look up the limit for N on the trend test table
If Q is less than the limit the two variables are related
If Q is greater than or equal to the limit the pattern could have occurred from random
chance
19
Scatter Diagram Example
The ZZ-400 manufacturing team suspects a relationship between product purity
(percent purity) and the amount of iron (measured in parts per million or ppm) Purity
and iron are plotted against each other as a scatter diagram as shown in the figure
below
There are 24 data points Median lines are drawn so that 12 points fall on each side for
both percent purity and ppm iron
To test for a relationship they calculate
A = points in upper left + points in lower right = 9 + 9 = 18
B = points in upper right + points in lower left = 3 + 3 = 6
Q = the smaller of A and B = the smaller of 18 and 6 = 6
N = A + B = 18 + 6 = 24
20
Then they look up the limit for N on the trend test table For N = 24 the limit is 6
Q is equal to the limit Therefore the pattern could have occurred from random
chance and no relationship is demonstrated
Scatter Diagram Example
Scatter Diagram Considerations
Here are some examples of situations in which might you use a scatter diagram
Variable A is the temperature of a reaction after 15 minutes Variable B measures the
colour of the product You suspect higher temperature makes the product darker Plot
temperature and colour on a scatter diagram
Variable A is the number of employees trained on new software and variable B is the
number of calls to the computer helps line You suspect that more training reduces the
number of calls Plot number of people trained versus number of calls
To test for autocorrelation of a measurement being monitored on a control chart plot
this pair of variables Variable A is the measurement at a given time Variable B is the
same measurement but at the previous time If the scatter diagram shows correlation
do another diagram where variable B is the measurement two times previously Keep
increasing the separation between the two times until the scatter diagram shows no
correlation
21
Even if the scatter diagram shows a relationship do not assume that one variable
caused the other Both may be influenced by a third variable
When the data are plotted the more the diagram resembles a straight line the stronger
the relationship
If a line is not clear statistics (N and Q) determine whether there is reasonable
certainty that a relationship exists If the statistics say that no relationship exists the
pattern could have occurred by random chance
If the scatter diagram shows no relationship between the variables consider whether
the data might be stratified
If the diagram shows no relationship consider whether the independent (x-axis)
variable has been varied widely Sometimes a relationship is not apparent because the
data donrsquot cover a wide enough range
Think creatively about how to use scatter diagrams to discover a root cause
Drawing a scatter diagram is the first step in looking for a relationship between
variables
22
7) Stratification
Stratification is a technique used in combination with other data analysis tools When
data from a variety of sources or categories have been lumped together the meaning
of the data can be impossible to see This technique separates the data so that patterns
can be seen
When to Use Stratification
Before collecting data
When data come from several sources or conditions such as shifts days of the
week suppliers or population groups
When data analysis may require separating different sources or conditions
Stratification Procedure
Before collecting data consider which information about the sources of the data
might have an effect on the results Set up the data collection so that you collect that
information as well
When plotting or graphing the collected data on a scatter diagram control chart
histogram or other analysis tool use different marks or colours to distinguish data
from various sources Data that are distinguished in this way are said to be
ldquostratifiedrdquo
Analyze the subsets of stratified data separately For example on a scatter diagram
where data are stratified into data from source 1 and data from source 2 draw
quadrants count points and determine the critical value only for the data from source
1 then only for the data from source 2
Stratification Example
23
The ZZndash400 manufacturing team drew a scatter diagram to test whether product
purity and iron contamination were related but the plot did not demonstrate a
relationship Then a team member realized that the data came from three different
reactors The team member redrew the diagram using a different symbol for each
reactorrsquos data
Now patterns can be seen The data from reactor 2 and reactor 3 are circled Even
without doing any calculations it is clear that for those two reactors purity decreases
as iron increases However the data from reactor 1 the solid dots that are not circled
do not show that relationship Something is different about reactor 1
Stratification Considerations
Here are examples of different sources that might require data to be stratified
Equipment
Shifts
Departments
24
Materials
Suppliers
Day of the week
Time of day
Products
Survey data usually benefit from stratification
Always consider before collecting data whether stratification might be needed during
analysis Plan to collect stratification information After the data are collected it might
be too late
On your graph or chart include a legend that identifies the marks or colours used
25
Now starting with new 7 quality control tool
Need of new quality control tool
Many customer requirements cannot always be adequately expressed by numerical
data alone Nevertheless even verbal statements can be expressions of facts because
it represents facts we ought to use Verbal data as well as numerical data in
controlling the managing quality It provides both quality control as well as
improvement during the manufacturing process
Benefits of new 7 quality control tool
Combine verbal with Numerical data
Looking for root cause
Clarify prioritize goals and schedule
Involve everyone into full cooperation and generate new ideas 1048577
The first new quality control tool is
1) Affinity Diagram
Application
An affinity diagram is used to organize into groupings large number of ideas opinions
or concerns about a Particular topic
Description
When a large number of ideas opinions or other concerns about a particular topic are
being collected this tool organizes the information into grouping~~based on the
natural relationships that exist among them The process is designed to stimulate
creativity and full participation It works best in groups of limited Size (a maximum
26
of eight members is recommended) in which members are accustomed to working
together This tool is often used to organize ideas generated by brainstorming
Procedure
State the topic to be studied in broad terms(details may prejudice the
response)
Record as many individual ideas opinions or concerns as possible on cards
(one per
card)
Mix the cards and spread them randomly on a large table
Group related cards together as follows
a)sort cards that seem to be related into groups and
b) limit number of grouping to ten without forcing single cards into groups
Locate or create a header card that captures the meaning of each group
Place this header card on top
Transfer the information from cards onto paper organized by groupings
Example For next generation digital camera we can organize the customer
Complains and requirements in an Affinity Diagram1048577
27
Affinity diagram
28
2) Tree diagram
Application
A tree diagram is used to show the interrelation between a topic and its component
elements
Description
A tree diagram systematically breaks down a topic into its component elements Ideas
generated by
Brainstorming and graphed or clustered with an affinity diagram can be converted
into a tree diagram
to show logical and sequential links This tool can be used in planning and problem
solving
Procedure
State the topic to be studied clearly
Define the major categories of the topic(brainstorm or use the header cards
from the affinity diagram)
Construct the diagram by placing the topic in a box on the left-hand side
Branch the major categories laterally to the right
For each major category define the component elements and sub-elements if
any
Laterally branch to the right the component elements and sub-elements for
each major category and
Review the diagram to ensure that there are no gaps in either sequence or
logic
29
30
3) Arrow diagram
Purpose To create a visual presentation of the steps of a process or tasks necessary to
complete a project with special emphasis on the time taken for these activities
Procedure
1 List all the tasks or activities needed to be accomplished before the process of the
project
2 Decide which steps are undertaken in series and which steps can be run in parallel
Arrange the
Activities in a proper sequence
3 Prepare lsquoEvent Nodesrsquo at the completion of steps and number them
4 Write the description of the step and decide the time required for completing each
step
5 Calculate the earliest time to reach an event node for the start of the process
7 Ager the time for all event nodes including the completion of the process or the
project is available one calculates the latest time by which an event node must be
reached
Application
The diagram is also useful in planning and scheduling steps in complicated processes
especially in planning and scheduling projects which involve a large number of
activities
Example
31
1 Identify the tasks Eg 123hellip15
2 Know the time each task needs
3 Determine which tasks can be run in parallel and in normal sequences
4 Draw the sequence diagram and find the critical path
5 Calculate the project duration
6 Calculate the earliest starting time (or the earliest finishing time of last task) and the
latest finishing time
of each task(the latest starting time for the following task)
7 Mark the time indication
32
33
4) Process Decision Program Chart (PDPC)
Def The process decision program chart (PDPC) method helps us select the best
processes to obtain optimum results by evaluating the progress of events and various
conceivable outcomes
Description
The process decision program chart (PDPC) method is used to define the solution
process when dealing with problems that have more than one possible outcome [t
anticipates the unexpected Outcomes at each stage and plans for it
PDPC has two following patterns
Pattern I ndash In this pattern process starts with initial condition lsquoArsquo and proceeds to the
desired final condition lsquoZrsquo in an organized manner
Pattern 11- In this pattern first the final conditionrsquosrsquo is set Then the process from lsquoZrsquo
to the initial point lsquoArsquo is developed with the inclusion of various alternatives from
many points of view
Procedure
Discuss the issues related to the project among a cross-functional team
Discuss which issues must be examined and identify those issues
Consider and note down all the anticipated results for the identified issues
Weigh the feasibility of each solution proposed and investigate alternate
solutions
Classify each issue according to its urgency number of operations required
likelihood of Occurrence and difficulty
Consider the anticipated results and alternative solutions related to issues that
must be addressed immediately and link the items with arrows to the desired
goal
34
Prioritize the different issues and consider them all together Information
related to one set of
Possibilities could influence another set Related items shall be linked with a
broken line
If the department that will handle a process involving several lines is
determined circle
the process and write the name of the department within
Set a target date for completion
Have regular meetings to check progress in terms of the original PDPC
35
36
37
38
5) Matrix diagram
Purpose1) Explore the existence and the extent of relations between individual items in 2 sets
of factors or features and characteristics and express them in a symbolic form that is
easy to understand
2) Mostly used to understand the relations between the customer expectations as
expressed by the customers and product characteristics as designed manufactured and
tested by the manufacturer
Procedures1 Determine 2 sets of factors for which the relations are needed to be established
2 Divide the features and characteristics into primary secondary and tertiary
characteristics
3 Place the features vertically on the leg side of the matrix and characteristics
horizontally on top of the matrix
4 Enter the importance of the features on the column ager that for the tertiary
features10485775 In the main body of the matrix use the symbols to represent the degree of
connections between the feature and characteristics
6 Choose and define relationship symbols Most commonly used symbols are as
given below
Strong relationship=
Relationship =
Likely relationship=
Application
bull Matrix diagram can be used to solve problems by arranging data in such a way that
the relations between relevant factors are brought into sharp focus
bull There is no limit to the use of the tool
39
bull The most important application of matrix diagram is in clarifying relations between
individual features of customer requirements and individual product characteristics
Example 1
Matrix Diagram for Quality Functions and Responsibilities
40
41
6) Matrix Data Analysis Diagram1048577
Purpose
To present numerical data about two sets of factors in a matrix form and
analyze it to get numerical output
Can be applied in understanding the products and products characteristics
Procedure1048577
1 Decide the two factors whose relations are to be analyzed
2 Check the number of individual items in the two factors
3 Prepare a matrix to accommodate all the items of the two factors
4 Enter numerical data in the matrix
5 Give the diagram a suitable title
Example
42
43
44
7) Relationship diagram
This diagram clarifies the interrelations in a complex situation involving many
interrelated factors and serves to clarify the cause and effect relationships among
factors
Description
Relations diagram is defined as a technique used to solve problems that have complex
cause and effect relationships among a number of problems and factors that influence
them
Format
A special feature of relation diagram is its unrestricted Format However general
formats are as given below
1) Centrally converging relations diagram
The major item or problem to be solved is located in the center and the related factors
are arranged around the item or problem in such a way as to indicate close
relationships
2) Directionally intensive relations diagram
The major item or problem to be solved is located on one side of the diagram and the
various factors arranged in accordance with the flow of their major cause-and-effect
relationships on the other side
3) Relationship indication relations diagram
There are no restrictions on this format because the main point is to arrange the cause-
and-effect Relationships of the application items or factors so that they are expressed
in a straightforward manner in a Diagram
45
Procedure
1) Define the issueproblem in such a way that it is clearly understood and agreed on
by team members
2) Assemble the cross-functional team
3) Layout all the ideasissue cards that have been brought from other tools
4) Look for causeinfluence relationships between all ideas and draw relationship
arrows
a) Choose any of the ideas as a starting point and work through them in sequence
b)An outgoing arrow from an idea indicates that it is the stronger cause or influence
c) Draw only one way relationship arrows in the direction of the stronger cause or
Influence Make a decision on the stronger direction Do not draw two headed arrows
5) Review and revise the relationsrsquo diagram
6) Tally the number of outgoing and incoming arrows and select key items for further
planning
-record and clearly mark next to each issue the number of arrows going in and out of
it
-find the items with the highest number outgoing arrows and the items with the
highest number of incoming arrows
-a high number of outgoing arrows indicate that the item is a root cause and should be
tackle first
46
-a high number of incoming arrows indicate that the item is a key outcome and may
become a focus for planning either as a meaningful measure of overall success or as a
redefinition of the original issue under discussion
Example
47
48
Conclusions
Statististical QC is chiefly concerned in making sure that several procedures
and working arrangements are in place to provide for effective and efficient
statistical processes to minimize the risk of errors or weaknesses in
procedures or systems or in source material
Seven QC tools are most helpful in troubleshooting issues related to quality
All processes are affected by multiple factors and therefore statistical QC tools
can be applied to any process
The continuous use of these tools upgrades the personnel characteristics of the
people involved It enhances their ability to think generate ideas solve
problem and do proper planning
49
References asqorglearn-about-qualityseven-basic-quality-toolsoverviewhtml
httpsenwikipediaorgwikiSeven_Basic_Tools_of_Quality
wwwijergsorgfilesdocumentsAPPLICATION-45pd
httpssrcalionsciencecompdfQualityToolspdf
www3haorghkqehwiserdoc7bqtpdf
wwwmathmunca~variyathNew7QCToolspd
50
- 1 DEFINITION of Quality Control
- 3 Competitiveness
- 4 Customer Loyalty
- 5 Reputation
- 6 Compliance
- 7 Costs
- Benefits of Using Quality Control in Manufacturing
-
3) Check sheets
Also called defect concentration diagram A check sheet is a structured prepared
form for collecting and analyzing data This is a generic tool that can be adapted for a
wide variety of purposes
When to Use a Check Sheet
When data can be observed and collected repeatedly by the same person or at
the same location
When collecting data on the frequency or patterns of events problems
defects defect location defect causes etc
When collecting data from a production process
Check Sheet Procedure
Decide what event or problem will be observed Develop operational
definitions
Decide when data will be collected and for how long
Design the form Set it up so that data can be recorded simply by making
check marks or Xs or similar symbols and so that data do not have to be
recopied for analysis
Label all spaces on the form
Test the check sheet for a short trial period to be sure it collects the
appropriate data and is easy to use
Each time the targeted event or problem occurs record data on the check
sheet
Check Sheet Example
The figure below shows a check sheet used to collect data on telephone interruptions
The tick marks were added as data was collected over several weeks
11
12
4) Control chart
The control chart is a graph used to study how a process changes over time Data are
plotted in time order A control chart always has a central line for the average an
upper line for the upper control limit and a lower line for the lower control limit
These lines are determined from historical data By comparing current data to these
lines you can draw conclusions about whether the process variation is consistent (in
control) or is unpredictable (out of control affected by special causes of variation)
Control charts for variable data are used in pairs The top chart monitors the average
or the centring of the distribution of data from the process The bottom chart monitors
the range or the width of the distribution If your data were shots in target practice
the average is where the shots are clustering and the range is how tightly they are
clustered Control charts for attribute data are used singly
41 When to Use a Control Chart
When controlling ongoing processes by finding and correcting problems as they
occur
When predicting the expected range of outcomes from a process
When determining whether a process is stable (in statistical control)
When analyzing patterns of process variation from special causes (non-routine
events) or common causes (built into the process)
When determining whether your quality improvement project should aim to
prevent specific problems or to make fundamental changes to the process
Control Chart Basic Procedure
Choose the appropriate control chart for your data
Determine the appropriate time period for collecting and plotting data
13
Collect data construct your chart and analyze the data
Look for ldquoout-of-control signalsrdquo on the control chart When one is identified mark it
on the chart and investigate the cause Document how you investigated what you
learned the cause and how it was corrected
Out-of-control signals
A single point outside the control limits In Figure 1 point sixteen is above the UCL
(upper control limit)
Two out of three successive points are on the same side of the centreline and farther
than 2 σ from it In Figure 1 point 4 sends that signal
Four out of five successive points are on the same side of the centreline and farther
than 1 σ from it In Figure 1 point 11 sends that signal
A run of eight in a row are on the same side of the centreline Or 10 out of 11 12 out
of 14 or 16 out of 20 In Figure 1 point 21 is eighth in a row above the centreline
Obvious consistent or persistent patterns that suggest something unusual about your
data and your process
5 Continue to plot data as they are generated As each new data point is plotted
check for new out-of-control signals
14
6 When you start a new control chart the process may be out of control If so the
control limits calculated from the first 20 points are conditional limits When you
have at least 20 sequential points from a period when the process is operating in
control recalculate control limits
5) Histogram chart
A frequency distribution shows how often each different value in a set of data occurs
A histogram is the most commonly used graph to show frequency distributions It
looks very much like a bar chart but there are important differences between them
When to Use a Histogram
When the data are numerical
When you want to see the shape of the datarsquos distribution especially when
determining whether the output of a process is distributed approximately
normally
When analyzing whether a process can meet the customerrsquos requirements
When analyzing what the output from a supplierrsquos process looks like
When seeing whether a process change has occurred from one time period to
another
When determining whether the outputs of two or more processes are different
When you wish to communicate the distribution of data quickly and easily to
others
Histogram Construction
Collect at least 50 consecutive data points from a process
Use the histogram worksheet to set up the histogram It will help you determine the
number of bars the range of numbers that go into each bar and the labels for the bar
edges After calculating W in step 2 of the worksheet use your judgment to adjust it
to a convenient number For example you might decide to round 09 to an even 10
15
The value for W must not have more decimal places than the numbers you will be
graphing
Draw x- and y-axes on graph paper Mark and label the y-axis for counting data
values Mark and label the x-axis with the L values from the worksheet The spaces
between these numbers will be the bars of the histogram Do not allow for spaces
between bars
For each data point mark off one count above the appropriate bar with an X or by
shading that portion of the bar
Histogram Analysis
Before drawing any conclusions from your histogram satisfy yourself that the process
was operating normally during the time period being studied If any unusual events
affected the process during the time period of the histogram your analysis of the
histogram shape probably cannot be generalized to all time periods
Analyze the meaning of your histogramrsquo
16
17
6) Scatter chart
The scatter diagram graphs pairs of numerical data with one variable on each axis to
look for a relationship between them If the variables are correlated the points will
fall along a line or curve The better the correlation the tighter the points will hug the
line
When to Use a Scatter Diagram
When you have paired numerical data
When your dependent variable may have multiple values for each value of your
independent variable
When trying to determine whether the two variables are related such ashellip
When trying to identify potential root causes of problems
After brainstorming causes and effects using a fishbone diagram to determine
objectively whether a particular cause and effect are related
When determining whether two effects that appears to be related both occur with the
same cause
When testing for autocorrelation before constructing a control chart
Scatter Diagram Procedure
Collect pairs of data where a relationship is suspected
Draw a graph with the independent variable on the horizontal axis and the dependent
variable on the vertical axis For each pair of data put a dot or a symbol where the x-
axis value intersects the y-axis value (If two dots fall together put them side by side
touching so that you can see both)
18
Look at the pattern of points to see if a relationship is obvious If the data clearly form
a line or a curve you may stop The variables are correlated You may wish to use
regression or correlation analysis now Otherwise complete steps 4 through 7
Divide points on the graph into four quadrants If there are X points on the graph
Count X2 points from top to bottom and draw a horizontal line
Count X2 points from left to right and draw a vertical line
If number of points is odd draw the line through the middle point
Count the points in each quadrant Do not count points on a line
Add the diagonally opposite quadrants Find the smaller sum and the total of points in
all quadrants
A = points in upper left + points in lower right
B = points in upper right + points in lower left
Q = the smaller of A and B
N = A + B
Look up the limit for N on the trend test table
If Q is less than the limit the two variables are related
If Q is greater than or equal to the limit the pattern could have occurred from random
chance
19
Scatter Diagram Example
The ZZ-400 manufacturing team suspects a relationship between product purity
(percent purity) and the amount of iron (measured in parts per million or ppm) Purity
and iron are plotted against each other as a scatter diagram as shown in the figure
below
There are 24 data points Median lines are drawn so that 12 points fall on each side for
both percent purity and ppm iron
To test for a relationship they calculate
A = points in upper left + points in lower right = 9 + 9 = 18
B = points in upper right + points in lower left = 3 + 3 = 6
Q = the smaller of A and B = the smaller of 18 and 6 = 6
N = A + B = 18 + 6 = 24
20
Then they look up the limit for N on the trend test table For N = 24 the limit is 6
Q is equal to the limit Therefore the pattern could have occurred from random
chance and no relationship is demonstrated
Scatter Diagram Example
Scatter Diagram Considerations
Here are some examples of situations in which might you use a scatter diagram
Variable A is the temperature of a reaction after 15 minutes Variable B measures the
colour of the product You suspect higher temperature makes the product darker Plot
temperature and colour on a scatter diagram
Variable A is the number of employees trained on new software and variable B is the
number of calls to the computer helps line You suspect that more training reduces the
number of calls Plot number of people trained versus number of calls
To test for autocorrelation of a measurement being monitored on a control chart plot
this pair of variables Variable A is the measurement at a given time Variable B is the
same measurement but at the previous time If the scatter diagram shows correlation
do another diagram where variable B is the measurement two times previously Keep
increasing the separation between the two times until the scatter diagram shows no
correlation
21
Even if the scatter diagram shows a relationship do not assume that one variable
caused the other Both may be influenced by a third variable
When the data are plotted the more the diagram resembles a straight line the stronger
the relationship
If a line is not clear statistics (N and Q) determine whether there is reasonable
certainty that a relationship exists If the statistics say that no relationship exists the
pattern could have occurred by random chance
If the scatter diagram shows no relationship between the variables consider whether
the data might be stratified
If the diagram shows no relationship consider whether the independent (x-axis)
variable has been varied widely Sometimes a relationship is not apparent because the
data donrsquot cover a wide enough range
Think creatively about how to use scatter diagrams to discover a root cause
Drawing a scatter diagram is the first step in looking for a relationship between
variables
22
7) Stratification
Stratification is a technique used in combination with other data analysis tools When
data from a variety of sources or categories have been lumped together the meaning
of the data can be impossible to see This technique separates the data so that patterns
can be seen
When to Use Stratification
Before collecting data
When data come from several sources or conditions such as shifts days of the
week suppliers or population groups
When data analysis may require separating different sources or conditions
Stratification Procedure
Before collecting data consider which information about the sources of the data
might have an effect on the results Set up the data collection so that you collect that
information as well
When plotting or graphing the collected data on a scatter diagram control chart
histogram or other analysis tool use different marks or colours to distinguish data
from various sources Data that are distinguished in this way are said to be
ldquostratifiedrdquo
Analyze the subsets of stratified data separately For example on a scatter diagram
where data are stratified into data from source 1 and data from source 2 draw
quadrants count points and determine the critical value only for the data from source
1 then only for the data from source 2
Stratification Example
23
The ZZndash400 manufacturing team drew a scatter diagram to test whether product
purity and iron contamination were related but the plot did not demonstrate a
relationship Then a team member realized that the data came from three different
reactors The team member redrew the diagram using a different symbol for each
reactorrsquos data
Now patterns can be seen The data from reactor 2 and reactor 3 are circled Even
without doing any calculations it is clear that for those two reactors purity decreases
as iron increases However the data from reactor 1 the solid dots that are not circled
do not show that relationship Something is different about reactor 1
Stratification Considerations
Here are examples of different sources that might require data to be stratified
Equipment
Shifts
Departments
24
Materials
Suppliers
Day of the week
Time of day
Products
Survey data usually benefit from stratification
Always consider before collecting data whether stratification might be needed during
analysis Plan to collect stratification information After the data are collected it might
be too late
On your graph or chart include a legend that identifies the marks or colours used
25
Now starting with new 7 quality control tool
Need of new quality control tool
Many customer requirements cannot always be adequately expressed by numerical
data alone Nevertheless even verbal statements can be expressions of facts because
it represents facts we ought to use Verbal data as well as numerical data in
controlling the managing quality It provides both quality control as well as
improvement during the manufacturing process
Benefits of new 7 quality control tool
Combine verbal with Numerical data
Looking for root cause
Clarify prioritize goals and schedule
Involve everyone into full cooperation and generate new ideas 1048577
The first new quality control tool is
1) Affinity Diagram
Application
An affinity diagram is used to organize into groupings large number of ideas opinions
or concerns about a Particular topic
Description
When a large number of ideas opinions or other concerns about a particular topic are
being collected this tool organizes the information into grouping~~based on the
natural relationships that exist among them The process is designed to stimulate
creativity and full participation It works best in groups of limited Size (a maximum
26
of eight members is recommended) in which members are accustomed to working
together This tool is often used to organize ideas generated by brainstorming
Procedure
State the topic to be studied in broad terms(details may prejudice the
response)
Record as many individual ideas opinions or concerns as possible on cards
(one per
card)
Mix the cards and spread them randomly on a large table
Group related cards together as follows
a)sort cards that seem to be related into groups and
b) limit number of grouping to ten without forcing single cards into groups
Locate or create a header card that captures the meaning of each group
Place this header card on top
Transfer the information from cards onto paper organized by groupings
Example For next generation digital camera we can organize the customer
Complains and requirements in an Affinity Diagram1048577
27
Affinity diagram
28
2) Tree diagram
Application
A tree diagram is used to show the interrelation between a topic and its component
elements
Description
A tree diagram systematically breaks down a topic into its component elements Ideas
generated by
Brainstorming and graphed or clustered with an affinity diagram can be converted
into a tree diagram
to show logical and sequential links This tool can be used in planning and problem
solving
Procedure
State the topic to be studied clearly
Define the major categories of the topic(brainstorm or use the header cards
from the affinity diagram)
Construct the diagram by placing the topic in a box on the left-hand side
Branch the major categories laterally to the right
For each major category define the component elements and sub-elements if
any
Laterally branch to the right the component elements and sub-elements for
each major category and
Review the diagram to ensure that there are no gaps in either sequence or
logic
29
30
3) Arrow diagram
Purpose To create a visual presentation of the steps of a process or tasks necessary to
complete a project with special emphasis on the time taken for these activities
Procedure
1 List all the tasks or activities needed to be accomplished before the process of the
project
2 Decide which steps are undertaken in series and which steps can be run in parallel
Arrange the
Activities in a proper sequence
3 Prepare lsquoEvent Nodesrsquo at the completion of steps and number them
4 Write the description of the step and decide the time required for completing each
step
5 Calculate the earliest time to reach an event node for the start of the process
7 Ager the time for all event nodes including the completion of the process or the
project is available one calculates the latest time by which an event node must be
reached
Application
The diagram is also useful in planning and scheduling steps in complicated processes
especially in planning and scheduling projects which involve a large number of
activities
Example
31
1 Identify the tasks Eg 123hellip15
2 Know the time each task needs
3 Determine which tasks can be run in parallel and in normal sequences
4 Draw the sequence diagram and find the critical path
5 Calculate the project duration
6 Calculate the earliest starting time (or the earliest finishing time of last task) and the
latest finishing time
of each task(the latest starting time for the following task)
7 Mark the time indication
32
33
4) Process Decision Program Chart (PDPC)
Def The process decision program chart (PDPC) method helps us select the best
processes to obtain optimum results by evaluating the progress of events and various
conceivable outcomes
Description
The process decision program chart (PDPC) method is used to define the solution
process when dealing with problems that have more than one possible outcome [t
anticipates the unexpected Outcomes at each stage and plans for it
PDPC has two following patterns
Pattern I ndash In this pattern process starts with initial condition lsquoArsquo and proceeds to the
desired final condition lsquoZrsquo in an organized manner
Pattern 11- In this pattern first the final conditionrsquosrsquo is set Then the process from lsquoZrsquo
to the initial point lsquoArsquo is developed with the inclusion of various alternatives from
many points of view
Procedure
Discuss the issues related to the project among a cross-functional team
Discuss which issues must be examined and identify those issues
Consider and note down all the anticipated results for the identified issues
Weigh the feasibility of each solution proposed and investigate alternate
solutions
Classify each issue according to its urgency number of operations required
likelihood of Occurrence and difficulty
Consider the anticipated results and alternative solutions related to issues that
must be addressed immediately and link the items with arrows to the desired
goal
34
Prioritize the different issues and consider them all together Information
related to one set of
Possibilities could influence another set Related items shall be linked with a
broken line
If the department that will handle a process involving several lines is
determined circle
the process and write the name of the department within
Set a target date for completion
Have regular meetings to check progress in terms of the original PDPC
35
36
37
38
5) Matrix diagram
Purpose1) Explore the existence and the extent of relations between individual items in 2 sets
of factors or features and characteristics and express them in a symbolic form that is
easy to understand
2) Mostly used to understand the relations between the customer expectations as
expressed by the customers and product characteristics as designed manufactured and
tested by the manufacturer
Procedures1 Determine 2 sets of factors for which the relations are needed to be established
2 Divide the features and characteristics into primary secondary and tertiary
characteristics
3 Place the features vertically on the leg side of the matrix and characteristics
horizontally on top of the matrix
4 Enter the importance of the features on the column ager that for the tertiary
features10485775 In the main body of the matrix use the symbols to represent the degree of
connections between the feature and characteristics
6 Choose and define relationship symbols Most commonly used symbols are as
given below
Strong relationship=
Relationship =
Likely relationship=
Application
bull Matrix diagram can be used to solve problems by arranging data in such a way that
the relations between relevant factors are brought into sharp focus
bull There is no limit to the use of the tool
39
bull The most important application of matrix diagram is in clarifying relations between
individual features of customer requirements and individual product characteristics
Example 1
Matrix Diagram for Quality Functions and Responsibilities
40
41
6) Matrix Data Analysis Diagram1048577
Purpose
To present numerical data about two sets of factors in a matrix form and
analyze it to get numerical output
Can be applied in understanding the products and products characteristics
Procedure1048577
1 Decide the two factors whose relations are to be analyzed
2 Check the number of individual items in the two factors
3 Prepare a matrix to accommodate all the items of the two factors
4 Enter numerical data in the matrix
5 Give the diagram a suitable title
Example
42
43
44
7) Relationship diagram
This diagram clarifies the interrelations in a complex situation involving many
interrelated factors and serves to clarify the cause and effect relationships among
factors
Description
Relations diagram is defined as a technique used to solve problems that have complex
cause and effect relationships among a number of problems and factors that influence
them
Format
A special feature of relation diagram is its unrestricted Format However general
formats are as given below
1) Centrally converging relations diagram
The major item or problem to be solved is located in the center and the related factors
are arranged around the item or problem in such a way as to indicate close
relationships
2) Directionally intensive relations diagram
The major item or problem to be solved is located on one side of the diagram and the
various factors arranged in accordance with the flow of their major cause-and-effect
relationships on the other side
3) Relationship indication relations diagram
There are no restrictions on this format because the main point is to arrange the cause-
and-effect Relationships of the application items or factors so that they are expressed
in a straightforward manner in a Diagram
45
Procedure
1) Define the issueproblem in such a way that it is clearly understood and agreed on
by team members
2) Assemble the cross-functional team
3) Layout all the ideasissue cards that have been brought from other tools
4) Look for causeinfluence relationships between all ideas and draw relationship
arrows
a) Choose any of the ideas as a starting point and work through them in sequence
b)An outgoing arrow from an idea indicates that it is the stronger cause or influence
c) Draw only one way relationship arrows in the direction of the stronger cause or
Influence Make a decision on the stronger direction Do not draw two headed arrows
5) Review and revise the relationsrsquo diagram
6) Tally the number of outgoing and incoming arrows and select key items for further
planning
-record and clearly mark next to each issue the number of arrows going in and out of
it
-find the items with the highest number outgoing arrows and the items with the
highest number of incoming arrows
-a high number of outgoing arrows indicate that the item is a root cause and should be
tackle first
46
-a high number of incoming arrows indicate that the item is a key outcome and may
become a focus for planning either as a meaningful measure of overall success or as a
redefinition of the original issue under discussion
Example
47
48
Conclusions
Statististical QC is chiefly concerned in making sure that several procedures
and working arrangements are in place to provide for effective and efficient
statistical processes to minimize the risk of errors or weaknesses in
procedures or systems or in source material
Seven QC tools are most helpful in troubleshooting issues related to quality
All processes are affected by multiple factors and therefore statistical QC tools
can be applied to any process
The continuous use of these tools upgrades the personnel characteristics of the
people involved It enhances their ability to think generate ideas solve
problem and do proper planning
49
References asqorglearn-about-qualityseven-basic-quality-toolsoverviewhtml
httpsenwikipediaorgwikiSeven_Basic_Tools_of_Quality
wwwijergsorgfilesdocumentsAPPLICATION-45pd
httpssrcalionsciencecompdfQualityToolspdf
www3haorghkqehwiserdoc7bqtpdf
wwwmathmunca~variyathNew7QCToolspd
50
- 1 DEFINITION of Quality Control
- 3 Competitiveness
- 4 Customer Loyalty
- 5 Reputation
- 6 Compliance
- 7 Costs
- Benefits of Using Quality Control in Manufacturing
-
12
4) Control chart
The control chart is a graph used to study how a process changes over time Data are
plotted in time order A control chart always has a central line for the average an
upper line for the upper control limit and a lower line for the lower control limit
These lines are determined from historical data By comparing current data to these
lines you can draw conclusions about whether the process variation is consistent (in
control) or is unpredictable (out of control affected by special causes of variation)
Control charts for variable data are used in pairs The top chart monitors the average
or the centring of the distribution of data from the process The bottom chart monitors
the range or the width of the distribution If your data were shots in target practice
the average is where the shots are clustering and the range is how tightly they are
clustered Control charts for attribute data are used singly
41 When to Use a Control Chart
When controlling ongoing processes by finding and correcting problems as they
occur
When predicting the expected range of outcomes from a process
When determining whether a process is stable (in statistical control)
When analyzing patterns of process variation from special causes (non-routine
events) or common causes (built into the process)
When determining whether your quality improvement project should aim to
prevent specific problems or to make fundamental changes to the process
Control Chart Basic Procedure
Choose the appropriate control chart for your data
Determine the appropriate time period for collecting and plotting data
13
Collect data construct your chart and analyze the data
Look for ldquoout-of-control signalsrdquo on the control chart When one is identified mark it
on the chart and investigate the cause Document how you investigated what you
learned the cause and how it was corrected
Out-of-control signals
A single point outside the control limits In Figure 1 point sixteen is above the UCL
(upper control limit)
Two out of three successive points are on the same side of the centreline and farther
than 2 σ from it In Figure 1 point 4 sends that signal
Four out of five successive points are on the same side of the centreline and farther
than 1 σ from it In Figure 1 point 11 sends that signal
A run of eight in a row are on the same side of the centreline Or 10 out of 11 12 out
of 14 or 16 out of 20 In Figure 1 point 21 is eighth in a row above the centreline
Obvious consistent or persistent patterns that suggest something unusual about your
data and your process
5 Continue to plot data as they are generated As each new data point is plotted
check for new out-of-control signals
14
6 When you start a new control chart the process may be out of control If so the
control limits calculated from the first 20 points are conditional limits When you
have at least 20 sequential points from a period when the process is operating in
control recalculate control limits
5) Histogram chart
A frequency distribution shows how often each different value in a set of data occurs
A histogram is the most commonly used graph to show frequency distributions It
looks very much like a bar chart but there are important differences between them
When to Use a Histogram
When the data are numerical
When you want to see the shape of the datarsquos distribution especially when
determining whether the output of a process is distributed approximately
normally
When analyzing whether a process can meet the customerrsquos requirements
When analyzing what the output from a supplierrsquos process looks like
When seeing whether a process change has occurred from one time period to
another
When determining whether the outputs of two or more processes are different
When you wish to communicate the distribution of data quickly and easily to
others
Histogram Construction
Collect at least 50 consecutive data points from a process
Use the histogram worksheet to set up the histogram It will help you determine the
number of bars the range of numbers that go into each bar and the labels for the bar
edges After calculating W in step 2 of the worksheet use your judgment to adjust it
to a convenient number For example you might decide to round 09 to an even 10
15
The value for W must not have more decimal places than the numbers you will be
graphing
Draw x- and y-axes on graph paper Mark and label the y-axis for counting data
values Mark and label the x-axis with the L values from the worksheet The spaces
between these numbers will be the bars of the histogram Do not allow for spaces
between bars
For each data point mark off one count above the appropriate bar with an X or by
shading that portion of the bar
Histogram Analysis
Before drawing any conclusions from your histogram satisfy yourself that the process
was operating normally during the time period being studied If any unusual events
affected the process during the time period of the histogram your analysis of the
histogram shape probably cannot be generalized to all time periods
Analyze the meaning of your histogramrsquo
16
17
6) Scatter chart
The scatter diagram graphs pairs of numerical data with one variable on each axis to
look for a relationship between them If the variables are correlated the points will
fall along a line or curve The better the correlation the tighter the points will hug the
line
When to Use a Scatter Diagram
When you have paired numerical data
When your dependent variable may have multiple values for each value of your
independent variable
When trying to determine whether the two variables are related such ashellip
When trying to identify potential root causes of problems
After brainstorming causes and effects using a fishbone diagram to determine
objectively whether a particular cause and effect are related
When determining whether two effects that appears to be related both occur with the
same cause
When testing for autocorrelation before constructing a control chart
Scatter Diagram Procedure
Collect pairs of data where a relationship is suspected
Draw a graph with the independent variable on the horizontal axis and the dependent
variable on the vertical axis For each pair of data put a dot or a symbol where the x-
axis value intersects the y-axis value (If two dots fall together put them side by side
touching so that you can see both)
18
Look at the pattern of points to see if a relationship is obvious If the data clearly form
a line or a curve you may stop The variables are correlated You may wish to use
regression or correlation analysis now Otherwise complete steps 4 through 7
Divide points on the graph into four quadrants If there are X points on the graph
Count X2 points from top to bottom and draw a horizontal line
Count X2 points from left to right and draw a vertical line
If number of points is odd draw the line through the middle point
Count the points in each quadrant Do not count points on a line
Add the diagonally opposite quadrants Find the smaller sum and the total of points in
all quadrants
A = points in upper left + points in lower right
B = points in upper right + points in lower left
Q = the smaller of A and B
N = A + B
Look up the limit for N on the trend test table
If Q is less than the limit the two variables are related
If Q is greater than or equal to the limit the pattern could have occurred from random
chance
19
Scatter Diagram Example
The ZZ-400 manufacturing team suspects a relationship between product purity
(percent purity) and the amount of iron (measured in parts per million or ppm) Purity
and iron are plotted against each other as a scatter diagram as shown in the figure
below
There are 24 data points Median lines are drawn so that 12 points fall on each side for
both percent purity and ppm iron
To test for a relationship they calculate
A = points in upper left + points in lower right = 9 + 9 = 18
B = points in upper right + points in lower left = 3 + 3 = 6
Q = the smaller of A and B = the smaller of 18 and 6 = 6
N = A + B = 18 + 6 = 24
20
Then they look up the limit for N on the trend test table For N = 24 the limit is 6
Q is equal to the limit Therefore the pattern could have occurred from random
chance and no relationship is demonstrated
Scatter Diagram Example
Scatter Diagram Considerations
Here are some examples of situations in which might you use a scatter diagram
Variable A is the temperature of a reaction after 15 minutes Variable B measures the
colour of the product You suspect higher temperature makes the product darker Plot
temperature and colour on a scatter diagram
Variable A is the number of employees trained on new software and variable B is the
number of calls to the computer helps line You suspect that more training reduces the
number of calls Plot number of people trained versus number of calls
To test for autocorrelation of a measurement being monitored on a control chart plot
this pair of variables Variable A is the measurement at a given time Variable B is the
same measurement but at the previous time If the scatter diagram shows correlation
do another diagram where variable B is the measurement two times previously Keep
increasing the separation between the two times until the scatter diagram shows no
correlation
21
Even if the scatter diagram shows a relationship do not assume that one variable
caused the other Both may be influenced by a third variable
When the data are plotted the more the diagram resembles a straight line the stronger
the relationship
If a line is not clear statistics (N and Q) determine whether there is reasonable
certainty that a relationship exists If the statistics say that no relationship exists the
pattern could have occurred by random chance
If the scatter diagram shows no relationship between the variables consider whether
the data might be stratified
If the diagram shows no relationship consider whether the independent (x-axis)
variable has been varied widely Sometimes a relationship is not apparent because the
data donrsquot cover a wide enough range
Think creatively about how to use scatter diagrams to discover a root cause
Drawing a scatter diagram is the first step in looking for a relationship between
variables
22
7) Stratification
Stratification is a technique used in combination with other data analysis tools When
data from a variety of sources or categories have been lumped together the meaning
of the data can be impossible to see This technique separates the data so that patterns
can be seen
When to Use Stratification
Before collecting data
When data come from several sources or conditions such as shifts days of the
week suppliers or population groups
When data analysis may require separating different sources or conditions
Stratification Procedure
Before collecting data consider which information about the sources of the data
might have an effect on the results Set up the data collection so that you collect that
information as well
When plotting or graphing the collected data on a scatter diagram control chart
histogram or other analysis tool use different marks or colours to distinguish data
from various sources Data that are distinguished in this way are said to be
ldquostratifiedrdquo
Analyze the subsets of stratified data separately For example on a scatter diagram
where data are stratified into data from source 1 and data from source 2 draw
quadrants count points and determine the critical value only for the data from source
1 then only for the data from source 2
Stratification Example
23
The ZZndash400 manufacturing team drew a scatter diagram to test whether product
purity and iron contamination were related but the plot did not demonstrate a
relationship Then a team member realized that the data came from three different
reactors The team member redrew the diagram using a different symbol for each
reactorrsquos data
Now patterns can be seen The data from reactor 2 and reactor 3 are circled Even
without doing any calculations it is clear that for those two reactors purity decreases
as iron increases However the data from reactor 1 the solid dots that are not circled
do not show that relationship Something is different about reactor 1
Stratification Considerations
Here are examples of different sources that might require data to be stratified
Equipment
Shifts
Departments
24
Materials
Suppliers
Day of the week
Time of day
Products
Survey data usually benefit from stratification
Always consider before collecting data whether stratification might be needed during
analysis Plan to collect stratification information After the data are collected it might
be too late
On your graph or chart include a legend that identifies the marks or colours used
25
Now starting with new 7 quality control tool
Need of new quality control tool
Many customer requirements cannot always be adequately expressed by numerical
data alone Nevertheless even verbal statements can be expressions of facts because
it represents facts we ought to use Verbal data as well as numerical data in
controlling the managing quality It provides both quality control as well as
improvement during the manufacturing process
Benefits of new 7 quality control tool
Combine verbal with Numerical data
Looking for root cause
Clarify prioritize goals and schedule
Involve everyone into full cooperation and generate new ideas 1048577
The first new quality control tool is
1) Affinity Diagram
Application
An affinity diagram is used to organize into groupings large number of ideas opinions
or concerns about a Particular topic
Description
When a large number of ideas opinions or other concerns about a particular topic are
being collected this tool organizes the information into grouping~~based on the
natural relationships that exist among them The process is designed to stimulate
creativity and full participation It works best in groups of limited Size (a maximum
26
of eight members is recommended) in which members are accustomed to working
together This tool is often used to organize ideas generated by brainstorming
Procedure
State the topic to be studied in broad terms(details may prejudice the
response)
Record as many individual ideas opinions or concerns as possible on cards
(one per
card)
Mix the cards and spread them randomly on a large table
Group related cards together as follows
a)sort cards that seem to be related into groups and
b) limit number of grouping to ten without forcing single cards into groups
Locate or create a header card that captures the meaning of each group
Place this header card on top
Transfer the information from cards onto paper organized by groupings
Example For next generation digital camera we can organize the customer
Complains and requirements in an Affinity Diagram1048577
27
Affinity diagram
28
2) Tree diagram
Application
A tree diagram is used to show the interrelation between a topic and its component
elements
Description
A tree diagram systematically breaks down a topic into its component elements Ideas
generated by
Brainstorming and graphed or clustered with an affinity diagram can be converted
into a tree diagram
to show logical and sequential links This tool can be used in planning and problem
solving
Procedure
State the topic to be studied clearly
Define the major categories of the topic(brainstorm or use the header cards
from the affinity diagram)
Construct the diagram by placing the topic in a box on the left-hand side
Branch the major categories laterally to the right
For each major category define the component elements and sub-elements if
any
Laterally branch to the right the component elements and sub-elements for
each major category and
Review the diagram to ensure that there are no gaps in either sequence or
logic
29
30
3) Arrow diagram
Purpose To create a visual presentation of the steps of a process or tasks necessary to
complete a project with special emphasis on the time taken for these activities
Procedure
1 List all the tasks or activities needed to be accomplished before the process of the
project
2 Decide which steps are undertaken in series and which steps can be run in parallel
Arrange the
Activities in a proper sequence
3 Prepare lsquoEvent Nodesrsquo at the completion of steps and number them
4 Write the description of the step and decide the time required for completing each
step
5 Calculate the earliest time to reach an event node for the start of the process
7 Ager the time for all event nodes including the completion of the process or the
project is available one calculates the latest time by which an event node must be
reached
Application
The diagram is also useful in planning and scheduling steps in complicated processes
especially in planning and scheduling projects which involve a large number of
activities
Example
31
1 Identify the tasks Eg 123hellip15
2 Know the time each task needs
3 Determine which tasks can be run in parallel and in normal sequences
4 Draw the sequence diagram and find the critical path
5 Calculate the project duration
6 Calculate the earliest starting time (or the earliest finishing time of last task) and the
latest finishing time
of each task(the latest starting time for the following task)
7 Mark the time indication
32
33
4) Process Decision Program Chart (PDPC)
Def The process decision program chart (PDPC) method helps us select the best
processes to obtain optimum results by evaluating the progress of events and various
conceivable outcomes
Description
The process decision program chart (PDPC) method is used to define the solution
process when dealing with problems that have more than one possible outcome [t
anticipates the unexpected Outcomes at each stage and plans for it
PDPC has two following patterns
Pattern I ndash In this pattern process starts with initial condition lsquoArsquo and proceeds to the
desired final condition lsquoZrsquo in an organized manner
Pattern 11- In this pattern first the final conditionrsquosrsquo is set Then the process from lsquoZrsquo
to the initial point lsquoArsquo is developed with the inclusion of various alternatives from
many points of view
Procedure
Discuss the issues related to the project among a cross-functional team
Discuss which issues must be examined and identify those issues
Consider and note down all the anticipated results for the identified issues
Weigh the feasibility of each solution proposed and investigate alternate
solutions
Classify each issue according to its urgency number of operations required
likelihood of Occurrence and difficulty
Consider the anticipated results and alternative solutions related to issues that
must be addressed immediately and link the items with arrows to the desired
goal
34
Prioritize the different issues and consider them all together Information
related to one set of
Possibilities could influence another set Related items shall be linked with a
broken line
If the department that will handle a process involving several lines is
determined circle
the process and write the name of the department within
Set a target date for completion
Have regular meetings to check progress in terms of the original PDPC
35
36
37
38
5) Matrix diagram
Purpose1) Explore the existence and the extent of relations between individual items in 2 sets
of factors or features and characteristics and express them in a symbolic form that is
easy to understand
2) Mostly used to understand the relations between the customer expectations as
expressed by the customers and product characteristics as designed manufactured and
tested by the manufacturer
Procedures1 Determine 2 sets of factors for which the relations are needed to be established
2 Divide the features and characteristics into primary secondary and tertiary
characteristics
3 Place the features vertically on the leg side of the matrix and characteristics
horizontally on top of the matrix
4 Enter the importance of the features on the column ager that for the tertiary
features10485775 In the main body of the matrix use the symbols to represent the degree of
connections between the feature and characteristics
6 Choose and define relationship symbols Most commonly used symbols are as
given below
Strong relationship=
Relationship =
Likely relationship=
Application
bull Matrix diagram can be used to solve problems by arranging data in such a way that
the relations between relevant factors are brought into sharp focus
bull There is no limit to the use of the tool
39
bull The most important application of matrix diagram is in clarifying relations between
individual features of customer requirements and individual product characteristics
Example 1
Matrix Diagram for Quality Functions and Responsibilities
40
41
6) Matrix Data Analysis Diagram1048577
Purpose
To present numerical data about two sets of factors in a matrix form and
analyze it to get numerical output
Can be applied in understanding the products and products characteristics
Procedure1048577
1 Decide the two factors whose relations are to be analyzed
2 Check the number of individual items in the two factors
3 Prepare a matrix to accommodate all the items of the two factors
4 Enter numerical data in the matrix
5 Give the diagram a suitable title
Example
42
43
44
7) Relationship diagram
This diagram clarifies the interrelations in a complex situation involving many
interrelated factors and serves to clarify the cause and effect relationships among
factors
Description
Relations diagram is defined as a technique used to solve problems that have complex
cause and effect relationships among a number of problems and factors that influence
them
Format
A special feature of relation diagram is its unrestricted Format However general
formats are as given below
1) Centrally converging relations diagram
The major item or problem to be solved is located in the center and the related factors
are arranged around the item or problem in such a way as to indicate close
relationships
2) Directionally intensive relations diagram
The major item or problem to be solved is located on one side of the diagram and the
various factors arranged in accordance with the flow of their major cause-and-effect
relationships on the other side
3) Relationship indication relations diagram
There are no restrictions on this format because the main point is to arrange the cause-
and-effect Relationships of the application items or factors so that they are expressed
in a straightforward manner in a Diagram
45
Procedure
1) Define the issueproblem in such a way that it is clearly understood and agreed on
by team members
2) Assemble the cross-functional team
3) Layout all the ideasissue cards that have been brought from other tools
4) Look for causeinfluence relationships between all ideas and draw relationship
arrows
a) Choose any of the ideas as a starting point and work through them in sequence
b)An outgoing arrow from an idea indicates that it is the stronger cause or influence
c) Draw only one way relationship arrows in the direction of the stronger cause or
Influence Make a decision on the stronger direction Do not draw two headed arrows
5) Review and revise the relationsrsquo diagram
6) Tally the number of outgoing and incoming arrows and select key items for further
planning
-record and clearly mark next to each issue the number of arrows going in and out of
it
-find the items with the highest number outgoing arrows and the items with the
highest number of incoming arrows
-a high number of outgoing arrows indicate that the item is a root cause and should be
tackle first
46
-a high number of incoming arrows indicate that the item is a key outcome and may
become a focus for planning either as a meaningful measure of overall success or as a
redefinition of the original issue under discussion
Example
47
48
Conclusions
Statististical QC is chiefly concerned in making sure that several procedures
and working arrangements are in place to provide for effective and efficient
statistical processes to minimize the risk of errors or weaknesses in
procedures or systems or in source material
Seven QC tools are most helpful in troubleshooting issues related to quality
All processes are affected by multiple factors and therefore statistical QC tools
can be applied to any process
The continuous use of these tools upgrades the personnel characteristics of the
people involved It enhances their ability to think generate ideas solve
problem and do proper planning
49
References asqorglearn-about-qualityseven-basic-quality-toolsoverviewhtml
httpsenwikipediaorgwikiSeven_Basic_Tools_of_Quality
wwwijergsorgfilesdocumentsAPPLICATION-45pd
httpssrcalionsciencecompdfQualityToolspdf
www3haorghkqehwiserdoc7bqtpdf
wwwmathmunca~variyathNew7QCToolspd
50
- 1 DEFINITION of Quality Control
- 3 Competitiveness
- 4 Customer Loyalty
- 5 Reputation
- 6 Compliance
- 7 Costs
- Benefits of Using Quality Control in Manufacturing
-
4) Control chart
The control chart is a graph used to study how a process changes over time Data are
plotted in time order A control chart always has a central line for the average an
upper line for the upper control limit and a lower line for the lower control limit
These lines are determined from historical data By comparing current data to these
lines you can draw conclusions about whether the process variation is consistent (in
control) or is unpredictable (out of control affected by special causes of variation)
Control charts for variable data are used in pairs The top chart monitors the average
or the centring of the distribution of data from the process The bottom chart monitors
the range or the width of the distribution If your data were shots in target practice
the average is where the shots are clustering and the range is how tightly they are
clustered Control charts for attribute data are used singly
41 When to Use a Control Chart
When controlling ongoing processes by finding and correcting problems as they
occur
When predicting the expected range of outcomes from a process
When determining whether a process is stable (in statistical control)
When analyzing patterns of process variation from special causes (non-routine
events) or common causes (built into the process)
When determining whether your quality improvement project should aim to
prevent specific problems or to make fundamental changes to the process
Control Chart Basic Procedure
Choose the appropriate control chart for your data
Determine the appropriate time period for collecting and plotting data
13
Collect data construct your chart and analyze the data
Look for ldquoout-of-control signalsrdquo on the control chart When one is identified mark it
on the chart and investigate the cause Document how you investigated what you
learned the cause and how it was corrected
Out-of-control signals
A single point outside the control limits In Figure 1 point sixteen is above the UCL
(upper control limit)
Two out of three successive points are on the same side of the centreline and farther
than 2 σ from it In Figure 1 point 4 sends that signal
Four out of five successive points are on the same side of the centreline and farther
than 1 σ from it In Figure 1 point 11 sends that signal
A run of eight in a row are on the same side of the centreline Or 10 out of 11 12 out
of 14 or 16 out of 20 In Figure 1 point 21 is eighth in a row above the centreline
Obvious consistent or persistent patterns that suggest something unusual about your
data and your process
5 Continue to plot data as they are generated As each new data point is plotted
check for new out-of-control signals
14
6 When you start a new control chart the process may be out of control If so the
control limits calculated from the first 20 points are conditional limits When you
have at least 20 sequential points from a period when the process is operating in
control recalculate control limits
5) Histogram chart
A frequency distribution shows how often each different value in a set of data occurs
A histogram is the most commonly used graph to show frequency distributions It
looks very much like a bar chart but there are important differences between them
When to Use a Histogram
When the data are numerical
When you want to see the shape of the datarsquos distribution especially when
determining whether the output of a process is distributed approximately
normally
When analyzing whether a process can meet the customerrsquos requirements
When analyzing what the output from a supplierrsquos process looks like
When seeing whether a process change has occurred from one time period to
another
When determining whether the outputs of two or more processes are different
When you wish to communicate the distribution of data quickly and easily to
others
Histogram Construction
Collect at least 50 consecutive data points from a process
Use the histogram worksheet to set up the histogram It will help you determine the
number of bars the range of numbers that go into each bar and the labels for the bar
edges After calculating W in step 2 of the worksheet use your judgment to adjust it
to a convenient number For example you might decide to round 09 to an even 10
15
The value for W must not have more decimal places than the numbers you will be
graphing
Draw x- and y-axes on graph paper Mark and label the y-axis for counting data
values Mark and label the x-axis with the L values from the worksheet The spaces
between these numbers will be the bars of the histogram Do not allow for spaces
between bars
For each data point mark off one count above the appropriate bar with an X or by
shading that portion of the bar
Histogram Analysis
Before drawing any conclusions from your histogram satisfy yourself that the process
was operating normally during the time period being studied If any unusual events
affected the process during the time period of the histogram your analysis of the
histogram shape probably cannot be generalized to all time periods
Analyze the meaning of your histogramrsquo
16
17
6) Scatter chart
The scatter diagram graphs pairs of numerical data with one variable on each axis to
look for a relationship between them If the variables are correlated the points will
fall along a line or curve The better the correlation the tighter the points will hug the
line
When to Use a Scatter Diagram
When you have paired numerical data
When your dependent variable may have multiple values for each value of your
independent variable
When trying to determine whether the two variables are related such ashellip
When trying to identify potential root causes of problems
After brainstorming causes and effects using a fishbone diagram to determine
objectively whether a particular cause and effect are related
When determining whether two effects that appears to be related both occur with the
same cause
When testing for autocorrelation before constructing a control chart
Scatter Diagram Procedure
Collect pairs of data where a relationship is suspected
Draw a graph with the independent variable on the horizontal axis and the dependent
variable on the vertical axis For each pair of data put a dot or a symbol where the x-
axis value intersects the y-axis value (If two dots fall together put them side by side
touching so that you can see both)
18
Look at the pattern of points to see if a relationship is obvious If the data clearly form
a line or a curve you may stop The variables are correlated You may wish to use
regression or correlation analysis now Otherwise complete steps 4 through 7
Divide points on the graph into four quadrants If there are X points on the graph
Count X2 points from top to bottom and draw a horizontal line
Count X2 points from left to right and draw a vertical line
If number of points is odd draw the line through the middle point
Count the points in each quadrant Do not count points on a line
Add the diagonally opposite quadrants Find the smaller sum and the total of points in
all quadrants
A = points in upper left + points in lower right
B = points in upper right + points in lower left
Q = the smaller of A and B
N = A + B
Look up the limit for N on the trend test table
If Q is less than the limit the two variables are related
If Q is greater than or equal to the limit the pattern could have occurred from random
chance
19
Scatter Diagram Example
The ZZ-400 manufacturing team suspects a relationship between product purity
(percent purity) and the amount of iron (measured in parts per million or ppm) Purity
and iron are plotted against each other as a scatter diagram as shown in the figure
below
There are 24 data points Median lines are drawn so that 12 points fall on each side for
both percent purity and ppm iron
To test for a relationship they calculate
A = points in upper left + points in lower right = 9 + 9 = 18
B = points in upper right + points in lower left = 3 + 3 = 6
Q = the smaller of A and B = the smaller of 18 and 6 = 6
N = A + B = 18 + 6 = 24
20
Then they look up the limit for N on the trend test table For N = 24 the limit is 6
Q is equal to the limit Therefore the pattern could have occurred from random
chance and no relationship is demonstrated
Scatter Diagram Example
Scatter Diagram Considerations
Here are some examples of situations in which might you use a scatter diagram
Variable A is the temperature of a reaction after 15 minutes Variable B measures the
colour of the product You suspect higher temperature makes the product darker Plot
temperature and colour on a scatter diagram
Variable A is the number of employees trained on new software and variable B is the
number of calls to the computer helps line You suspect that more training reduces the
number of calls Plot number of people trained versus number of calls
To test for autocorrelation of a measurement being monitored on a control chart plot
this pair of variables Variable A is the measurement at a given time Variable B is the
same measurement but at the previous time If the scatter diagram shows correlation
do another diagram where variable B is the measurement two times previously Keep
increasing the separation between the two times until the scatter diagram shows no
correlation
21
Even if the scatter diagram shows a relationship do not assume that one variable
caused the other Both may be influenced by a third variable
When the data are plotted the more the diagram resembles a straight line the stronger
the relationship
If a line is not clear statistics (N and Q) determine whether there is reasonable
certainty that a relationship exists If the statistics say that no relationship exists the
pattern could have occurred by random chance
If the scatter diagram shows no relationship between the variables consider whether
the data might be stratified
If the diagram shows no relationship consider whether the independent (x-axis)
variable has been varied widely Sometimes a relationship is not apparent because the
data donrsquot cover a wide enough range
Think creatively about how to use scatter diagrams to discover a root cause
Drawing a scatter diagram is the first step in looking for a relationship between
variables
22
7) Stratification
Stratification is a technique used in combination with other data analysis tools When
data from a variety of sources or categories have been lumped together the meaning
of the data can be impossible to see This technique separates the data so that patterns
can be seen
When to Use Stratification
Before collecting data
When data come from several sources or conditions such as shifts days of the
week suppliers or population groups
When data analysis may require separating different sources or conditions
Stratification Procedure
Before collecting data consider which information about the sources of the data
might have an effect on the results Set up the data collection so that you collect that
information as well
When plotting or graphing the collected data on a scatter diagram control chart
histogram or other analysis tool use different marks or colours to distinguish data
from various sources Data that are distinguished in this way are said to be
ldquostratifiedrdquo
Analyze the subsets of stratified data separately For example on a scatter diagram
where data are stratified into data from source 1 and data from source 2 draw
quadrants count points and determine the critical value only for the data from source
1 then only for the data from source 2
Stratification Example
23
The ZZndash400 manufacturing team drew a scatter diagram to test whether product
purity and iron contamination were related but the plot did not demonstrate a
relationship Then a team member realized that the data came from three different
reactors The team member redrew the diagram using a different symbol for each
reactorrsquos data
Now patterns can be seen The data from reactor 2 and reactor 3 are circled Even
without doing any calculations it is clear that for those two reactors purity decreases
as iron increases However the data from reactor 1 the solid dots that are not circled
do not show that relationship Something is different about reactor 1
Stratification Considerations
Here are examples of different sources that might require data to be stratified
Equipment
Shifts
Departments
24
Materials
Suppliers
Day of the week
Time of day
Products
Survey data usually benefit from stratification
Always consider before collecting data whether stratification might be needed during
analysis Plan to collect stratification information After the data are collected it might
be too late
On your graph or chart include a legend that identifies the marks or colours used
25
Now starting with new 7 quality control tool
Need of new quality control tool
Many customer requirements cannot always be adequately expressed by numerical
data alone Nevertheless even verbal statements can be expressions of facts because
it represents facts we ought to use Verbal data as well as numerical data in
controlling the managing quality It provides both quality control as well as
improvement during the manufacturing process
Benefits of new 7 quality control tool
Combine verbal with Numerical data
Looking for root cause
Clarify prioritize goals and schedule
Involve everyone into full cooperation and generate new ideas 1048577
The first new quality control tool is
1) Affinity Diagram
Application
An affinity diagram is used to organize into groupings large number of ideas opinions
or concerns about a Particular topic
Description
When a large number of ideas opinions or other concerns about a particular topic are
being collected this tool organizes the information into grouping~~based on the
natural relationships that exist among them The process is designed to stimulate
creativity and full participation It works best in groups of limited Size (a maximum
26
of eight members is recommended) in which members are accustomed to working
together This tool is often used to organize ideas generated by brainstorming
Procedure
State the topic to be studied in broad terms(details may prejudice the
response)
Record as many individual ideas opinions or concerns as possible on cards
(one per
card)
Mix the cards and spread them randomly on a large table
Group related cards together as follows
a)sort cards that seem to be related into groups and
b) limit number of grouping to ten without forcing single cards into groups
Locate or create a header card that captures the meaning of each group
Place this header card on top
Transfer the information from cards onto paper organized by groupings
Example For next generation digital camera we can organize the customer
Complains and requirements in an Affinity Diagram1048577
27
Affinity diagram
28
2) Tree diagram
Application
A tree diagram is used to show the interrelation between a topic and its component
elements
Description
A tree diagram systematically breaks down a topic into its component elements Ideas
generated by
Brainstorming and graphed or clustered with an affinity diagram can be converted
into a tree diagram
to show logical and sequential links This tool can be used in planning and problem
solving
Procedure
State the topic to be studied clearly
Define the major categories of the topic(brainstorm or use the header cards
from the affinity diagram)
Construct the diagram by placing the topic in a box on the left-hand side
Branch the major categories laterally to the right
For each major category define the component elements and sub-elements if
any
Laterally branch to the right the component elements and sub-elements for
each major category and
Review the diagram to ensure that there are no gaps in either sequence or
logic
29
30
3) Arrow diagram
Purpose To create a visual presentation of the steps of a process or tasks necessary to
complete a project with special emphasis on the time taken for these activities
Procedure
1 List all the tasks or activities needed to be accomplished before the process of the
project
2 Decide which steps are undertaken in series and which steps can be run in parallel
Arrange the
Activities in a proper sequence
3 Prepare lsquoEvent Nodesrsquo at the completion of steps and number them
4 Write the description of the step and decide the time required for completing each
step
5 Calculate the earliest time to reach an event node for the start of the process
7 Ager the time for all event nodes including the completion of the process or the
project is available one calculates the latest time by which an event node must be
reached
Application
The diagram is also useful in planning and scheduling steps in complicated processes
especially in planning and scheduling projects which involve a large number of
activities
Example
31
1 Identify the tasks Eg 123hellip15
2 Know the time each task needs
3 Determine which tasks can be run in parallel and in normal sequences
4 Draw the sequence diagram and find the critical path
5 Calculate the project duration
6 Calculate the earliest starting time (or the earliest finishing time of last task) and the
latest finishing time
of each task(the latest starting time for the following task)
7 Mark the time indication
32
33
4) Process Decision Program Chart (PDPC)
Def The process decision program chart (PDPC) method helps us select the best
processes to obtain optimum results by evaluating the progress of events and various
conceivable outcomes
Description
The process decision program chart (PDPC) method is used to define the solution
process when dealing with problems that have more than one possible outcome [t
anticipates the unexpected Outcomes at each stage and plans for it
PDPC has two following patterns
Pattern I ndash In this pattern process starts with initial condition lsquoArsquo and proceeds to the
desired final condition lsquoZrsquo in an organized manner
Pattern 11- In this pattern first the final conditionrsquosrsquo is set Then the process from lsquoZrsquo
to the initial point lsquoArsquo is developed with the inclusion of various alternatives from
many points of view
Procedure
Discuss the issues related to the project among a cross-functional team
Discuss which issues must be examined and identify those issues
Consider and note down all the anticipated results for the identified issues
Weigh the feasibility of each solution proposed and investigate alternate
solutions
Classify each issue according to its urgency number of operations required
likelihood of Occurrence and difficulty
Consider the anticipated results and alternative solutions related to issues that
must be addressed immediately and link the items with arrows to the desired
goal
34
Prioritize the different issues and consider them all together Information
related to one set of
Possibilities could influence another set Related items shall be linked with a
broken line
If the department that will handle a process involving several lines is
determined circle
the process and write the name of the department within
Set a target date for completion
Have regular meetings to check progress in terms of the original PDPC
35
36
37
38
5) Matrix diagram
Purpose1) Explore the existence and the extent of relations between individual items in 2 sets
of factors or features and characteristics and express them in a symbolic form that is
easy to understand
2) Mostly used to understand the relations between the customer expectations as
expressed by the customers and product characteristics as designed manufactured and
tested by the manufacturer
Procedures1 Determine 2 sets of factors for which the relations are needed to be established
2 Divide the features and characteristics into primary secondary and tertiary
characteristics
3 Place the features vertically on the leg side of the matrix and characteristics
horizontally on top of the matrix
4 Enter the importance of the features on the column ager that for the tertiary
features10485775 In the main body of the matrix use the symbols to represent the degree of
connections between the feature and characteristics
6 Choose and define relationship symbols Most commonly used symbols are as
given below
Strong relationship=
Relationship =
Likely relationship=
Application
bull Matrix diagram can be used to solve problems by arranging data in such a way that
the relations between relevant factors are brought into sharp focus
bull There is no limit to the use of the tool
39
bull The most important application of matrix diagram is in clarifying relations between
individual features of customer requirements and individual product characteristics
Example 1
Matrix Diagram for Quality Functions and Responsibilities
40
41
6) Matrix Data Analysis Diagram1048577
Purpose
To present numerical data about two sets of factors in a matrix form and
analyze it to get numerical output
Can be applied in understanding the products and products characteristics
Procedure1048577
1 Decide the two factors whose relations are to be analyzed
2 Check the number of individual items in the two factors
3 Prepare a matrix to accommodate all the items of the two factors
4 Enter numerical data in the matrix
5 Give the diagram a suitable title
Example
42
43
44
7) Relationship diagram
This diagram clarifies the interrelations in a complex situation involving many
interrelated factors and serves to clarify the cause and effect relationships among
factors
Description
Relations diagram is defined as a technique used to solve problems that have complex
cause and effect relationships among a number of problems and factors that influence
them
Format
A special feature of relation diagram is its unrestricted Format However general
formats are as given below
1) Centrally converging relations diagram
The major item or problem to be solved is located in the center and the related factors
are arranged around the item or problem in such a way as to indicate close
relationships
2) Directionally intensive relations diagram
The major item or problem to be solved is located on one side of the diagram and the
various factors arranged in accordance with the flow of their major cause-and-effect
relationships on the other side
3) Relationship indication relations diagram
There are no restrictions on this format because the main point is to arrange the cause-
and-effect Relationships of the application items or factors so that they are expressed
in a straightforward manner in a Diagram
45
Procedure
1) Define the issueproblem in such a way that it is clearly understood and agreed on
by team members
2) Assemble the cross-functional team
3) Layout all the ideasissue cards that have been brought from other tools
4) Look for causeinfluence relationships between all ideas and draw relationship
arrows
a) Choose any of the ideas as a starting point and work through them in sequence
b)An outgoing arrow from an idea indicates that it is the stronger cause or influence
c) Draw only one way relationship arrows in the direction of the stronger cause or
Influence Make a decision on the stronger direction Do not draw two headed arrows
5) Review and revise the relationsrsquo diagram
6) Tally the number of outgoing and incoming arrows and select key items for further
planning
-record and clearly mark next to each issue the number of arrows going in and out of
it
-find the items with the highest number outgoing arrows and the items with the
highest number of incoming arrows
-a high number of outgoing arrows indicate that the item is a root cause and should be
tackle first
46
-a high number of incoming arrows indicate that the item is a key outcome and may
become a focus for planning either as a meaningful measure of overall success or as a
redefinition of the original issue under discussion
Example
47
48
Conclusions
Statististical QC is chiefly concerned in making sure that several procedures
and working arrangements are in place to provide for effective and efficient
statistical processes to minimize the risk of errors or weaknesses in
procedures or systems or in source material
Seven QC tools are most helpful in troubleshooting issues related to quality
All processes are affected by multiple factors and therefore statistical QC tools
can be applied to any process
The continuous use of these tools upgrades the personnel characteristics of the
people involved It enhances their ability to think generate ideas solve
problem and do proper planning
49
References asqorglearn-about-qualityseven-basic-quality-toolsoverviewhtml
httpsenwikipediaorgwikiSeven_Basic_Tools_of_Quality
wwwijergsorgfilesdocumentsAPPLICATION-45pd
httpssrcalionsciencecompdfQualityToolspdf
www3haorghkqehwiserdoc7bqtpdf
wwwmathmunca~variyathNew7QCToolspd
50
- 1 DEFINITION of Quality Control
- 3 Competitiveness
- 4 Customer Loyalty
- 5 Reputation
- 6 Compliance
- 7 Costs
- Benefits of Using Quality Control in Manufacturing
-
Collect data construct your chart and analyze the data
Look for ldquoout-of-control signalsrdquo on the control chart When one is identified mark it
on the chart and investigate the cause Document how you investigated what you
learned the cause and how it was corrected
Out-of-control signals
A single point outside the control limits In Figure 1 point sixteen is above the UCL
(upper control limit)
Two out of three successive points are on the same side of the centreline and farther
than 2 σ from it In Figure 1 point 4 sends that signal
Four out of five successive points are on the same side of the centreline and farther
than 1 σ from it In Figure 1 point 11 sends that signal
A run of eight in a row are on the same side of the centreline Or 10 out of 11 12 out
of 14 or 16 out of 20 In Figure 1 point 21 is eighth in a row above the centreline
Obvious consistent or persistent patterns that suggest something unusual about your
data and your process
5 Continue to plot data as they are generated As each new data point is plotted
check for new out-of-control signals
14
6 When you start a new control chart the process may be out of control If so the
control limits calculated from the first 20 points are conditional limits When you
have at least 20 sequential points from a period when the process is operating in
control recalculate control limits
5) Histogram chart
A frequency distribution shows how often each different value in a set of data occurs
A histogram is the most commonly used graph to show frequency distributions It
looks very much like a bar chart but there are important differences between them
When to Use a Histogram
When the data are numerical
When you want to see the shape of the datarsquos distribution especially when
determining whether the output of a process is distributed approximately
normally
When analyzing whether a process can meet the customerrsquos requirements
When analyzing what the output from a supplierrsquos process looks like
When seeing whether a process change has occurred from one time period to
another
When determining whether the outputs of two or more processes are different
When you wish to communicate the distribution of data quickly and easily to
others
Histogram Construction
Collect at least 50 consecutive data points from a process
Use the histogram worksheet to set up the histogram It will help you determine the
number of bars the range of numbers that go into each bar and the labels for the bar
edges After calculating W in step 2 of the worksheet use your judgment to adjust it
to a convenient number For example you might decide to round 09 to an even 10
15
The value for W must not have more decimal places than the numbers you will be
graphing
Draw x- and y-axes on graph paper Mark and label the y-axis for counting data
values Mark and label the x-axis with the L values from the worksheet The spaces
between these numbers will be the bars of the histogram Do not allow for spaces
between bars
For each data point mark off one count above the appropriate bar with an X or by
shading that portion of the bar
Histogram Analysis
Before drawing any conclusions from your histogram satisfy yourself that the process
was operating normally during the time period being studied If any unusual events
affected the process during the time period of the histogram your analysis of the
histogram shape probably cannot be generalized to all time periods
Analyze the meaning of your histogramrsquo
16
17
6) Scatter chart
The scatter diagram graphs pairs of numerical data with one variable on each axis to
look for a relationship between them If the variables are correlated the points will
fall along a line or curve The better the correlation the tighter the points will hug the
line
When to Use a Scatter Diagram
When you have paired numerical data
When your dependent variable may have multiple values for each value of your
independent variable
When trying to determine whether the two variables are related such ashellip
When trying to identify potential root causes of problems
After brainstorming causes and effects using a fishbone diagram to determine
objectively whether a particular cause and effect are related
When determining whether two effects that appears to be related both occur with the
same cause
When testing for autocorrelation before constructing a control chart
Scatter Diagram Procedure
Collect pairs of data where a relationship is suspected
Draw a graph with the independent variable on the horizontal axis and the dependent
variable on the vertical axis For each pair of data put a dot or a symbol where the x-
axis value intersects the y-axis value (If two dots fall together put them side by side
touching so that you can see both)
18
Look at the pattern of points to see if a relationship is obvious If the data clearly form
a line or a curve you may stop The variables are correlated You may wish to use
regression or correlation analysis now Otherwise complete steps 4 through 7
Divide points on the graph into four quadrants If there are X points on the graph
Count X2 points from top to bottom and draw a horizontal line
Count X2 points from left to right and draw a vertical line
If number of points is odd draw the line through the middle point
Count the points in each quadrant Do not count points on a line
Add the diagonally opposite quadrants Find the smaller sum and the total of points in
all quadrants
A = points in upper left + points in lower right
B = points in upper right + points in lower left
Q = the smaller of A and B
N = A + B
Look up the limit for N on the trend test table
If Q is less than the limit the two variables are related
If Q is greater than or equal to the limit the pattern could have occurred from random
chance
19
Scatter Diagram Example
The ZZ-400 manufacturing team suspects a relationship between product purity
(percent purity) and the amount of iron (measured in parts per million or ppm) Purity
and iron are plotted against each other as a scatter diagram as shown in the figure
below
There are 24 data points Median lines are drawn so that 12 points fall on each side for
both percent purity and ppm iron
To test for a relationship they calculate
A = points in upper left + points in lower right = 9 + 9 = 18
B = points in upper right + points in lower left = 3 + 3 = 6
Q = the smaller of A and B = the smaller of 18 and 6 = 6
N = A + B = 18 + 6 = 24
20
Then they look up the limit for N on the trend test table For N = 24 the limit is 6
Q is equal to the limit Therefore the pattern could have occurred from random
chance and no relationship is demonstrated
Scatter Diagram Example
Scatter Diagram Considerations
Here are some examples of situations in which might you use a scatter diagram
Variable A is the temperature of a reaction after 15 minutes Variable B measures the
colour of the product You suspect higher temperature makes the product darker Plot
temperature and colour on a scatter diagram
Variable A is the number of employees trained on new software and variable B is the
number of calls to the computer helps line You suspect that more training reduces the
number of calls Plot number of people trained versus number of calls
To test for autocorrelation of a measurement being monitored on a control chart plot
this pair of variables Variable A is the measurement at a given time Variable B is the
same measurement but at the previous time If the scatter diagram shows correlation
do another diagram where variable B is the measurement two times previously Keep
increasing the separation between the two times until the scatter diagram shows no
correlation
21
Even if the scatter diagram shows a relationship do not assume that one variable
caused the other Both may be influenced by a third variable
When the data are plotted the more the diagram resembles a straight line the stronger
the relationship
If a line is not clear statistics (N and Q) determine whether there is reasonable
certainty that a relationship exists If the statistics say that no relationship exists the
pattern could have occurred by random chance
If the scatter diagram shows no relationship between the variables consider whether
the data might be stratified
If the diagram shows no relationship consider whether the independent (x-axis)
variable has been varied widely Sometimes a relationship is not apparent because the
data donrsquot cover a wide enough range
Think creatively about how to use scatter diagrams to discover a root cause
Drawing a scatter diagram is the first step in looking for a relationship between
variables
22
7) Stratification
Stratification is a technique used in combination with other data analysis tools When
data from a variety of sources or categories have been lumped together the meaning
of the data can be impossible to see This technique separates the data so that patterns
can be seen
When to Use Stratification
Before collecting data
When data come from several sources or conditions such as shifts days of the
week suppliers or population groups
When data analysis may require separating different sources or conditions
Stratification Procedure
Before collecting data consider which information about the sources of the data
might have an effect on the results Set up the data collection so that you collect that
information as well
When plotting or graphing the collected data on a scatter diagram control chart
histogram or other analysis tool use different marks or colours to distinguish data
from various sources Data that are distinguished in this way are said to be
ldquostratifiedrdquo
Analyze the subsets of stratified data separately For example on a scatter diagram
where data are stratified into data from source 1 and data from source 2 draw
quadrants count points and determine the critical value only for the data from source
1 then only for the data from source 2
Stratification Example
23
The ZZndash400 manufacturing team drew a scatter diagram to test whether product
purity and iron contamination were related but the plot did not demonstrate a
relationship Then a team member realized that the data came from three different
reactors The team member redrew the diagram using a different symbol for each
reactorrsquos data
Now patterns can be seen The data from reactor 2 and reactor 3 are circled Even
without doing any calculations it is clear that for those two reactors purity decreases
as iron increases However the data from reactor 1 the solid dots that are not circled
do not show that relationship Something is different about reactor 1
Stratification Considerations
Here are examples of different sources that might require data to be stratified
Equipment
Shifts
Departments
24
Materials
Suppliers
Day of the week
Time of day
Products
Survey data usually benefit from stratification
Always consider before collecting data whether stratification might be needed during
analysis Plan to collect stratification information After the data are collected it might
be too late
On your graph or chart include a legend that identifies the marks or colours used
25
Now starting with new 7 quality control tool
Need of new quality control tool
Many customer requirements cannot always be adequately expressed by numerical
data alone Nevertheless even verbal statements can be expressions of facts because
it represents facts we ought to use Verbal data as well as numerical data in
controlling the managing quality It provides both quality control as well as
improvement during the manufacturing process
Benefits of new 7 quality control tool
Combine verbal with Numerical data
Looking for root cause
Clarify prioritize goals and schedule
Involve everyone into full cooperation and generate new ideas 1048577
The first new quality control tool is
1) Affinity Diagram
Application
An affinity diagram is used to organize into groupings large number of ideas opinions
or concerns about a Particular topic
Description
When a large number of ideas opinions or other concerns about a particular topic are
being collected this tool organizes the information into grouping~~based on the
natural relationships that exist among them The process is designed to stimulate
creativity and full participation It works best in groups of limited Size (a maximum
26
of eight members is recommended) in which members are accustomed to working
together This tool is often used to organize ideas generated by brainstorming
Procedure
State the topic to be studied in broad terms(details may prejudice the
response)
Record as many individual ideas opinions or concerns as possible on cards
(one per
card)
Mix the cards and spread them randomly on a large table
Group related cards together as follows
a)sort cards that seem to be related into groups and
b) limit number of grouping to ten without forcing single cards into groups
Locate or create a header card that captures the meaning of each group
Place this header card on top
Transfer the information from cards onto paper organized by groupings
Example For next generation digital camera we can organize the customer
Complains and requirements in an Affinity Diagram1048577
27
Affinity diagram
28
2) Tree diagram
Application
A tree diagram is used to show the interrelation between a topic and its component
elements
Description
A tree diagram systematically breaks down a topic into its component elements Ideas
generated by
Brainstorming and graphed or clustered with an affinity diagram can be converted
into a tree diagram
to show logical and sequential links This tool can be used in planning and problem
solving
Procedure
State the topic to be studied clearly
Define the major categories of the topic(brainstorm or use the header cards
from the affinity diagram)
Construct the diagram by placing the topic in a box on the left-hand side
Branch the major categories laterally to the right
For each major category define the component elements and sub-elements if
any
Laterally branch to the right the component elements and sub-elements for
each major category and
Review the diagram to ensure that there are no gaps in either sequence or
logic
29
30
3) Arrow diagram
Purpose To create a visual presentation of the steps of a process or tasks necessary to
complete a project with special emphasis on the time taken for these activities
Procedure
1 List all the tasks or activities needed to be accomplished before the process of the
project
2 Decide which steps are undertaken in series and which steps can be run in parallel
Arrange the
Activities in a proper sequence
3 Prepare lsquoEvent Nodesrsquo at the completion of steps and number them
4 Write the description of the step and decide the time required for completing each
step
5 Calculate the earliest time to reach an event node for the start of the process
7 Ager the time for all event nodes including the completion of the process or the
project is available one calculates the latest time by which an event node must be
reached
Application
The diagram is also useful in planning and scheduling steps in complicated processes
especially in planning and scheduling projects which involve a large number of
activities
Example
31
1 Identify the tasks Eg 123hellip15
2 Know the time each task needs
3 Determine which tasks can be run in parallel and in normal sequences
4 Draw the sequence diagram and find the critical path
5 Calculate the project duration
6 Calculate the earliest starting time (or the earliest finishing time of last task) and the
latest finishing time
of each task(the latest starting time for the following task)
7 Mark the time indication
32
33
4) Process Decision Program Chart (PDPC)
Def The process decision program chart (PDPC) method helps us select the best
processes to obtain optimum results by evaluating the progress of events and various
conceivable outcomes
Description
The process decision program chart (PDPC) method is used to define the solution
process when dealing with problems that have more than one possible outcome [t
anticipates the unexpected Outcomes at each stage and plans for it
PDPC has two following patterns
Pattern I ndash In this pattern process starts with initial condition lsquoArsquo and proceeds to the
desired final condition lsquoZrsquo in an organized manner
Pattern 11- In this pattern first the final conditionrsquosrsquo is set Then the process from lsquoZrsquo
to the initial point lsquoArsquo is developed with the inclusion of various alternatives from
many points of view
Procedure
Discuss the issues related to the project among a cross-functional team
Discuss which issues must be examined and identify those issues
Consider and note down all the anticipated results for the identified issues
Weigh the feasibility of each solution proposed and investigate alternate
solutions
Classify each issue according to its urgency number of operations required
likelihood of Occurrence and difficulty
Consider the anticipated results and alternative solutions related to issues that
must be addressed immediately and link the items with arrows to the desired
goal
34
Prioritize the different issues and consider them all together Information
related to one set of
Possibilities could influence another set Related items shall be linked with a
broken line
If the department that will handle a process involving several lines is
determined circle
the process and write the name of the department within
Set a target date for completion
Have regular meetings to check progress in terms of the original PDPC
35
36
37
38
5) Matrix diagram
Purpose1) Explore the existence and the extent of relations between individual items in 2 sets
of factors or features and characteristics and express them in a symbolic form that is
easy to understand
2) Mostly used to understand the relations between the customer expectations as
expressed by the customers and product characteristics as designed manufactured and
tested by the manufacturer
Procedures1 Determine 2 sets of factors for which the relations are needed to be established
2 Divide the features and characteristics into primary secondary and tertiary
characteristics
3 Place the features vertically on the leg side of the matrix and characteristics
horizontally on top of the matrix
4 Enter the importance of the features on the column ager that for the tertiary
features10485775 In the main body of the matrix use the symbols to represent the degree of
connections between the feature and characteristics
6 Choose and define relationship symbols Most commonly used symbols are as
given below
Strong relationship=
Relationship =
Likely relationship=
Application
bull Matrix diagram can be used to solve problems by arranging data in such a way that
the relations between relevant factors are brought into sharp focus
bull There is no limit to the use of the tool
39
bull The most important application of matrix diagram is in clarifying relations between
individual features of customer requirements and individual product characteristics
Example 1
Matrix Diagram for Quality Functions and Responsibilities
40
41
6) Matrix Data Analysis Diagram1048577
Purpose
To present numerical data about two sets of factors in a matrix form and
analyze it to get numerical output
Can be applied in understanding the products and products characteristics
Procedure1048577
1 Decide the two factors whose relations are to be analyzed
2 Check the number of individual items in the two factors
3 Prepare a matrix to accommodate all the items of the two factors
4 Enter numerical data in the matrix
5 Give the diagram a suitable title
Example
42
43
44
7) Relationship diagram
This diagram clarifies the interrelations in a complex situation involving many
interrelated factors and serves to clarify the cause and effect relationships among
factors
Description
Relations diagram is defined as a technique used to solve problems that have complex
cause and effect relationships among a number of problems and factors that influence
them
Format
A special feature of relation diagram is its unrestricted Format However general
formats are as given below
1) Centrally converging relations diagram
The major item or problem to be solved is located in the center and the related factors
are arranged around the item or problem in such a way as to indicate close
relationships
2) Directionally intensive relations diagram
The major item or problem to be solved is located on one side of the diagram and the
various factors arranged in accordance with the flow of their major cause-and-effect
relationships on the other side
3) Relationship indication relations diagram
There are no restrictions on this format because the main point is to arrange the cause-
and-effect Relationships of the application items or factors so that they are expressed
in a straightforward manner in a Diagram
45
Procedure
1) Define the issueproblem in such a way that it is clearly understood and agreed on
by team members
2) Assemble the cross-functional team
3) Layout all the ideasissue cards that have been brought from other tools
4) Look for causeinfluence relationships between all ideas and draw relationship
arrows
a) Choose any of the ideas as a starting point and work through them in sequence
b)An outgoing arrow from an idea indicates that it is the stronger cause or influence
c) Draw only one way relationship arrows in the direction of the stronger cause or
Influence Make a decision on the stronger direction Do not draw two headed arrows
5) Review and revise the relationsrsquo diagram
6) Tally the number of outgoing and incoming arrows and select key items for further
planning
-record and clearly mark next to each issue the number of arrows going in and out of
it
-find the items with the highest number outgoing arrows and the items with the
highest number of incoming arrows
-a high number of outgoing arrows indicate that the item is a root cause and should be
tackle first
46
-a high number of incoming arrows indicate that the item is a key outcome and may
become a focus for planning either as a meaningful measure of overall success or as a
redefinition of the original issue under discussion
Example
47
48
Conclusions
Statististical QC is chiefly concerned in making sure that several procedures
and working arrangements are in place to provide for effective and efficient
statistical processes to minimize the risk of errors or weaknesses in
procedures or systems or in source material
Seven QC tools are most helpful in troubleshooting issues related to quality
All processes are affected by multiple factors and therefore statistical QC tools
can be applied to any process
The continuous use of these tools upgrades the personnel characteristics of the
people involved It enhances their ability to think generate ideas solve
problem and do proper planning
49
References asqorglearn-about-qualityseven-basic-quality-toolsoverviewhtml
httpsenwikipediaorgwikiSeven_Basic_Tools_of_Quality
wwwijergsorgfilesdocumentsAPPLICATION-45pd
httpssrcalionsciencecompdfQualityToolspdf
www3haorghkqehwiserdoc7bqtpdf
wwwmathmunca~variyathNew7QCToolspd
50
- 1 DEFINITION of Quality Control
- 3 Competitiveness
- 4 Customer Loyalty
- 5 Reputation
- 6 Compliance
- 7 Costs
- Benefits of Using Quality Control in Manufacturing
-
6 When you start a new control chart the process may be out of control If so the
control limits calculated from the first 20 points are conditional limits When you
have at least 20 sequential points from a period when the process is operating in
control recalculate control limits
5) Histogram chart
A frequency distribution shows how often each different value in a set of data occurs
A histogram is the most commonly used graph to show frequency distributions It
looks very much like a bar chart but there are important differences between them
When to Use a Histogram
When the data are numerical
When you want to see the shape of the datarsquos distribution especially when
determining whether the output of a process is distributed approximately
normally
When analyzing whether a process can meet the customerrsquos requirements
When analyzing what the output from a supplierrsquos process looks like
When seeing whether a process change has occurred from one time period to
another
When determining whether the outputs of two or more processes are different
When you wish to communicate the distribution of data quickly and easily to
others
Histogram Construction
Collect at least 50 consecutive data points from a process
Use the histogram worksheet to set up the histogram It will help you determine the
number of bars the range of numbers that go into each bar and the labels for the bar
edges After calculating W in step 2 of the worksheet use your judgment to adjust it
to a convenient number For example you might decide to round 09 to an even 10
15
The value for W must not have more decimal places than the numbers you will be
graphing
Draw x- and y-axes on graph paper Mark and label the y-axis for counting data
values Mark and label the x-axis with the L values from the worksheet The spaces
between these numbers will be the bars of the histogram Do not allow for spaces
between bars
For each data point mark off one count above the appropriate bar with an X or by
shading that portion of the bar
Histogram Analysis
Before drawing any conclusions from your histogram satisfy yourself that the process
was operating normally during the time period being studied If any unusual events
affected the process during the time period of the histogram your analysis of the
histogram shape probably cannot be generalized to all time periods
Analyze the meaning of your histogramrsquo
16
17
6) Scatter chart
The scatter diagram graphs pairs of numerical data with one variable on each axis to
look for a relationship between them If the variables are correlated the points will
fall along a line or curve The better the correlation the tighter the points will hug the
line
When to Use a Scatter Diagram
When you have paired numerical data
When your dependent variable may have multiple values for each value of your
independent variable
When trying to determine whether the two variables are related such ashellip
When trying to identify potential root causes of problems
After brainstorming causes and effects using a fishbone diagram to determine
objectively whether a particular cause and effect are related
When determining whether two effects that appears to be related both occur with the
same cause
When testing for autocorrelation before constructing a control chart
Scatter Diagram Procedure
Collect pairs of data where a relationship is suspected
Draw a graph with the independent variable on the horizontal axis and the dependent
variable on the vertical axis For each pair of data put a dot or a symbol where the x-
axis value intersects the y-axis value (If two dots fall together put them side by side
touching so that you can see both)
18
Look at the pattern of points to see if a relationship is obvious If the data clearly form
a line or a curve you may stop The variables are correlated You may wish to use
regression or correlation analysis now Otherwise complete steps 4 through 7
Divide points on the graph into four quadrants If there are X points on the graph
Count X2 points from top to bottom and draw a horizontal line
Count X2 points from left to right and draw a vertical line
If number of points is odd draw the line through the middle point
Count the points in each quadrant Do not count points on a line
Add the diagonally opposite quadrants Find the smaller sum and the total of points in
all quadrants
A = points in upper left + points in lower right
B = points in upper right + points in lower left
Q = the smaller of A and B
N = A + B
Look up the limit for N on the trend test table
If Q is less than the limit the two variables are related
If Q is greater than or equal to the limit the pattern could have occurred from random
chance
19
Scatter Diagram Example
The ZZ-400 manufacturing team suspects a relationship between product purity
(percent purity) and the amount of iron (measured in parts per million or ppm) Purity
and iron are plotted against each other as a scatter diagram as shown in the figure
below
There are 24 data points Median lines are drawn so that 12 points fall on each side for
both percent purity and ppm iron
To test for a relationship they calculate
A = points in upper left + points in lower right = 9 + 9 = 18
B = points in upper right + points in lower left = 3 + 3 = 6
Q = the smaller of A and B = the smaller of 18 and 6 = 6
N = A + B = 18 + 6 = 24
20
Then they look up the limit for N on the trend test table For N = 24 the limit is 6
Q is equal to the limit Therefore the pattern could have occurred from random
chance and no relationship is demonstrated
Scatter Diagram Example
Scatter Diagram Considerations
Here are some examples of situations in which might you use a scatter diagram
Variable A is the temperature of a reaction after 15 minutes Variable B measures the
colour of the product You suspect higher temperature makes the product darker Plot
temperature and colour on a scatter diagram
Variable A is the number of employees trained on new software and variable B is the
number of calls to the computer helps line You suspect that more training reduces the
number of calls Plot number of people trained versus number of calls
To test for autocorrelation of a measurement being monitored on a control chart plot
this pair of variables Variable A is the measurement at a given time Variable B is the
same measurement but at the previous time If the scatter diagram shows correlation
do another diagram where variable B is the measurement two times previously Keep
increasing the separation between the two times until the scatter diagram shows no
correlation
21
Even if the scatter diagram shows a relationship do not assume that one variable
caused the other Both may be influenced by a third variable
When the data are plotted the more the diagram resembles a straight line the stronger
the relationship
If a line is not clear statistics (N and Q) determine whether there is reasonable
certainty that a relationship exists If the statistics say that no relationship exists the
pattern could have occurred by random chance
If the scatter diagram shows no relationship between the variables consider whether
the data might be stratified
If the diagram shows no relationship consider whether the independent (x-axis)
variable has been varied widely Sometimes a relationship is not apparent because the
data donrsquot cover a wide enough range
Think creatively about how to use scatter diagrams to discover a root cause
Drawing a scatter diagram is the first step in looking for a relationship between
variables
22
7) Stratification
Stratification is a technique used in combination with other data analysis tools When
data from a variety of sources or categories have been lumped together the meaning
of the data can be impossible to see This technique separates the data so that patterns
can be seen
When to Use Stratification
Before collecting data
When data come from several sources or conditions such as shifts days of the
week suppliers or population groups
When data analysis may require separating different sources or conditions
Stratification Procedure
Before collecting data consider which information about the sources of the data
might have an effect on the results Set up the data collection so that you collect that
information as well
When plotting or graphing the collected data on a scatter diagram control chart
histogram or other analysis tool use different marks or colours to distinguish data
from various sources Data that are distinguished in this way are said to be
ldquostratifiedrdquo
Analyze the subsets of stratified data separately For example on a scatter diagram
where data are stratified into data from source 1 and data from source 2 draw
quadrants count points and determine the critical value only for the data from source
1 then only for the data from source 2
Stratification Example
23
The ZZndash400 manufacturing team drew a scatter diagram to test whether product
purity and iron contamination were related but the plot did not demonstrate a
relationship Then a team member realized that the data came from three different
reactors The team member redrew the diagram using a different symbol for each
reactorrsquos data
Now patterns can be seen The data from reactor 2 and reactor 3 are circled Even
without doing any calculations it is clear that for those two reactors purity decreases
as iron increases However the data from reactor 1 the solid dots that are not circled
do not show that relationship Something is different about reactor 1
Stratification Considerations
Here are examples of different sources that might require data to be stratified
Equipment
Shifts
Departments
24
Materials
Suppliers
Day of the week
Time of day
Products
Survey data usually benefit from stratification
Always consider before collecting data whether stratification might be needed during
analysis Plan to collect stratification information After the data are collected it might
be too late
On your graph or chart include a legend that identifies the marks or colours used
25
Now starting with new 7 quality control tool
Need of new quality control tool
Many customer requirements cannot always be adequately expressed by numerical
data alone Nevertheless even verbal statements can be expressions of facts because
it represents facts we ought to use Verbal data as well as numerical data in
controlling the managing quality It provides both quality control as well as
improvement during the manufacturing process
Benefits of new 7 quality control tool
Combine verbal with Numerical data
Looking for root cause
Clarify prioritize goals and schedule
Involve everyone into full cooperation and generate new ideas 1048577
The first new quality control tool is
1) Affinity Diagram
Application
An affinity diagram is used to organize into groupings large number of ideas opinions
or concerns about a Particular topic
Description
When a large number of ideas opinions or other concerns about a particular topic are
being collected this tool organizes the information into grouping~~based on the
natural relationships that exist among them The process is designed to stimulate
creativity and full participation It works best in groups of limited Size (a maximum
26
of eight members is recommended) in which members are accustomed to working
together This tool is often used to organize ideas generated by brainstorming
Procedure
State the topic to be studied in broad terms(details may prejudice the
response)
Record as many individual ideas opinions or concerns as possible on cards
(one per
card)
Mix the cards and spread them randomly on a large table
Group related cards together as follows
a)sort cards that seem to be related into groups and
b) limit number of grouping to ten without forcing single cards into groups
Locate or create a header card that captures the meaning of each group
Place this header card on top
Transfer the information from cards onto paper organized by groupings
Example For next generation digital camera we can organize the customer
Complains and requirements in an Affinity Diagram1048577
27
Affinity diagram
28
2) Tree diagram
Application
A tree diagram is used to show the interrelation between a topic and its component
elements
Description
A tree diagram systematically breaks down a topic into its component elements Ideas
generated by
Brainstorming and graphed or clustered with an affinity diagram can be converted
into a tree diagram
to show logical and sequential links This tool can be used in planning and problem
solving
Procedure
State the topic to be studied clearly
Define the major categories of the topic(brainstorm or use the header cards
from the affinity diagram)
Construct the diagram by placing the topic in a box on the left-hand side
Branch the major categories laterally to the right
For each major category define the component elements and sub-elements if
any
Laterally branch to the right the component elements and sub-elements for
each major category and
Review the diagram to ensure that there are no gaps in either sequence or
logic
29
30
3) Arrow diagram
Purpose To create a visual presentation of the steps of a process or tasks necessary to
complete a project with special emphasis on the time taken for these activities
Procedure
1 List all the tasks or activities needed to be accomplished before the process of the
project
2 Decide which steps are undertaken in series and which steps can be run in parallel
Arrange the
Activities in a proper sequence
3 Prepare lsquoEvent Nodesrsquo at the completion of steps and number them
4 Write the description of the step and decide the time required for completing each
step
5 Calculate the earliest time to reach an event node for the start of the process
7 Ager the time for all event nodes including the completion of the process or the
project is available one calculates the latest time by which an event node must be
reached
Application
The diagram is also useful in planning and scheduling steps in complicated processes
especially in planning and scheduling projects which involve a large number of
activities
Example
31
1 Identify the tasks Eg 123hellip15
2 Know the time each task needs
3 Determine which tasks can be run in parallel and in normal sequences
4 Draw the sequence diagram and find the critical path
5 Calculate the project duration
6 Calculate the earliest starting time (or the earliest finishing time of last task) and the
latest finishing time
of each task(the latest starting time for the following task)
7 Mark the time indication
32
33
4) Process Decision Program Chart (PDPC)
Def The process decision program chart (PDPC) method helps us select the best
processes to obtain optimum results by evaluating the progress of events and various
conceivable outcomes
Description
The process decision program chart (PDPC) method is used to define the solution
process when dealing with problems that have more than one possible outcome [t
anticipates the unexpected Outcomes at each stage and plans for it
PDPC has two following patterns
Pattern I ndash In this pattern process starts with initial condition lsquoArsquo and proceeds to the
desired final condition lsquoZrsquo in an organized manner
Pattern 11- In this pattern first the final conditionrsquosrsquo is set Then the process from lsquoZrsquo
to the initial point lsquoArsquo is developed with the inclusion of various alternatives from
many points of view
Procedure
Discuss the issues related to the project among a cross-functional team
Discuss which issues must be examined and identify those issues
Consider and note down all the anticipated results for the identified issues
Weigh the feasibility of each solution proposed and investigate alternate
solutions
Classify each issue according to its urgency number of operations required
likelihood of Occurrence and difficulty
Consider the anticipated results and alternative solutions related to issues that
must be addressed immediately and link the items with arrows to the desired
goal
34
Prioritize the different issues and consider them all together Information
related to one set of
Possibilities could influence another set Related items shall be linked with a
broken line
If the department that will handle a process involving several lines is
determined circle
the process and write the name of the department within
Set a target date for completion
Have regular meetings to check progress in terms of the original PDPC
35
36
37
38
5) Matrix diagram
Purpose1) Explore the existence and the extent of relations between individual items in 2 sets
of factors or features and characteristics and express them in a symbolic form that is
easy to understand
2) Mostly used to understand the relations between the customer expectations as
expressed by the customers and product characteristics as designed manufactured and
tested by the manufacturer
Procedures1 Determine 2 sets of factors for which the relations are needed to be established
2 Divide the features and characteristics into primary secondary and tertiary
characteristics
3 Place the features vertically on the leg side of the matrix and characteristics
horizontally on top of the matrix
4 Enter the importance of the features on the column ager that for the tertiary
features10485775 In the main body of the matrix use the symbols to represent the degree of
connections between the feature and characteristics
6 Choose and define relationship symbols Most commonly used symbols are as
given below
Strong relationship=
Relationship =
Likely relationship=
Application
bull Matrix diagram can be used to solve problems by arranging data in such a way that
the relations between relevant factors are brought into sharp focus
bull There is no limit to the use of the tool
39
bull The most important application of matrix diagram is in clarifying relations between
individual features of customer requirements and individual product characteristics
Example 1
Matrix Diagram for Quality Functions and Responsibilities
40
41
6) Matrix Data Analysis Diagram1048577
Purpose
To present numerical data about two sets of factors in a matrix form and
analyze it to get numerical output
Can be applied in understanding the products and products characteristics
Procedure1048577
1 Decide the two factors whose relations are to be analyzed
2 Check the number of individual items in the two factors
3 Prepare a matrix to accommodate all the items of the two factors
4 Enter numerical data in the matrix
5 Give the diagram a suitable title
Example
42
43
44
7) Relationship diagram
This diagram clarifies the interrelations in a complex situation involving many
interrelated factors and serves to clarify the cause and effect relationships among
factors
Description
Relations diagram is defined as a technique used to solve problems that have complex
cause and effect relationships among a number of problems and factors that influence
them
Format
A special feature of relation diagram is its unrestricted Format However general
formats are as given below
1) Centrally converging relations diagram
The major item or problem to be solved is located in the center and the related factors
are arranged around the item or problem in such a way as to indicate close
relationships
2) Directionally intensive relations diagram
The major item or problem to be solved is located on one side of the diagram and the
various factors arranged in accordance with the flow of their major cause-and-effect
relationships on the other side
3) Relationship indication relations diagram
There are no restrictions on this format because the main point is to arrange the cause-
and-effect Relationships of the application items or factors so that they are expressed
in a straightforward manner in a Diagram
45
Procedure
1) Define the issueproblem in such a way that it is clearly understood and agreed on
by team members
2) Assemble the cross-functional team
3) Layout all the ideasissue cards that have been brought from other tools
4) Look for causeinfluence relationships between all ideas and draw relationship
arrows
a) Choose any of the ideas as a starting point and work through them in sequence
b)An outgoing arrow from an idea indicates that it is the stronger cause or influence
c) Draw only one way relationship arrows in the direction of the stronger cause or
Influence Make a decision on the stronger direction Do not draw two headed arrows
5) Review and revise the relationsrsquo diagram
6) Tally the number of outgoing and incoming arrows and select key items for further
planning
-record and clearly mark next to each issue the number of arrows going in and out of
it
-find the items with the highest number outgoing arrows and the items with the
highest number of incoming arrows
-a high number of outgoing arrows indicate that the item is a root cause and should be
tackle first
46
-a high number of incoming arrows indicate that the item is a key outcome and may
become a focus for planning either as a meaningful measure of overall success or as a
redefinition of the original issue under discussion
Example
47
48
Conclusions
Statististical QC is chiefly concerned in making sure that several procedures
and working arrangements are in place to provide for effective and efficient
statistical processes to minimize the risk of errors or weaknesses in
procedures or systems or in source material
Seven QC tools are most helpful in troubleshooting issues related to quality
All processes are affected by multiple factors and therefore statistical QC tools
can be applied to any process
The continuous use of these tools upgrades the personnel characteristics of the
people involved It enhances their ability to think generate ideas solve
problem and do proper planning
49
References asqorglearn-about-qualityseven-basic-quality-toolsoverviewhtml
httpsenwikipediaorgwikiSeven_Basic_Tools_of_Quality
wwwijergsorgfilesdocumentsAPPLICATION-45pd
httpssrcalionsciencecompdfQualityToolspdf
www3haorghkqehwiserdoc7bqtpdf
wwwmathmunca~variyathNew7QCToolspd
50
- 1 DEFINITION of Quality Control
- 3 Competitiveness
- 4 Customer Loyalty
- 5 Reputation
- 6 Compliance
- 7 Costs
- Benefits of Using Quality Control in Manufacturing
-
The value for W must not have more decimal places than the numbers you will be
graphing
Draw x- and y-axes on graph paper Mark and label the y-axis for counting data
values Mark and label the x-axis with the L values from the worksheet The spaces
between these numbers will be the bars of the histogram Do not allow for spaces
between bars
For each data point mark off one count above the appropriate bar with an X or by
shading that portion of the bar
Histogram Analysis
Before drawing any conclusions from your histogram satisfy yourself that the process
was operating normally during the time period being studied If any unusual events
affected the process during the time period of the histogram your analysis of the
histogram shape probably cannot be generalized to all time periods
Analyze the meaning of your histogramrsquo
16
17
6) Scatter chart
The scatter diagram graphs pairs of numerical data with one variable on each axis to
look for a relationship between them If the variables are correlated the points will
fall along a line or curve The better the correlation the tighter the points will hug the
line
When to Use a Scatter Diagram
When you have paired numerical data
When your dependent variable may have multiple values for each value of your
independent variable
When trying to determine whether the two variables are related such ashellip
When trying to identify potential root causes of problems
After brainstorming causes and effects using a fishbone diagram to determine
objectively whether a particular cause and effect are related
When determining whether two effects that appears to be related both occur with the
same cause
When testing for autocorrelation before constructing a control chart
Scatter Diagram Procedure
Collect pairs of data where a relationship is suspected
Draw a graph with the independent variable on the horizontal axis and the dependent
variable on the vertical axis For each pair of data put a dot or a symbol where the x-
axis value intersects the y-axis value (If two dots fall together put them side by side
touching so that you can see both)
18
Look at the pattern of points to see if a relationship is obvious If the data clearly form
a line or a curve you may stop The variables are correlated You may wish to use
regression or correlation analysis now Otherwise complete steps 4 through 7
Divide points on the graph into four quadrants If there are X points on the graph
Count X2 points from top to bottom and draw a horizontal line
Count X2 points from left to right and draw a vertical line
If number of points is odd draw the line through the middle point
Count the points in each quadrant Do not count points on a line
Add the diagonally opposite quadrants Find the smaller sum and the total of points in
all quadrants
A = points in upper left + points in lower right
B = points in upper right + points in lower left
Q = the smaller of A and B
N = A + B
Look up the limit for N on the trend test table
If Q is less than the limit the two variables are related
If Q is greater than or equal to the limit the pattern could have occurred from random
chance
19
Scatter Diagram Example
The ZZ-400 manufacturing team suspects a relationship between product purity
(percent purity) and the amount of iron (measured in parts per million or ppm) Purity
and iron are plotted against each other as a scatter diagram as shown in the figure
below
There are 24 data points Median lines are drawn so that 12 points fall on each side for
both percent purity and ppm iron
To test for a relationship they calculate
A = points in upper left + points in lower right = 9 + 9 = 18
B = points in upper right + points in lower left = 3 + 3 = 6
Q = the smaller of A and B = the smaller of 18 and 6 = 6
N = A + B = 18 + 6 = 24
20
Then they look up the limit for N on the trend test table For N = 24 the limit is 6
Q is equal to the limit Therefore the pattern could have occurred from random
chance and no relationship is demonstrated
Scatter Diagram Example
Scatter Diagram Considerations
Here are some examples of situations in which might you use a scatter diagram
Variable A is the temperature of a reaction after 15 minutes Variable B measures the
colour of the product You suspect higher temperature makes the product darker Plot
temperature and colour on a scatter diagram
Variable A is the number of employees trained on new software and variable B is the
number of calls to the computer helps line You suspect that more training reduces the
number of calls Plot number of people trained versus number of calls
To test for autocorrelation of a measurement being monitored on a control chart plot
this pair of variables Variable A is the measurement at a given time Variable B is the
same measurement but at the previous time If the scatter diagram shows correlation
do another diagram where variable B is the measurement two times previously Keep
increasing the separation between the two times until the scatter diagram shows no
correlation
21
Even if the scatter diagram shows a relationship do not assume that one variable
caused the other Both may be influenced by a third variable
When the data are plotted the more the diagram resembles a straight line the stronger
the relationship
If a line is not clear statistics (N and Q) determine whether there is reasonable
certainty that a relationship exists If the statistics say that no relationship exists the
pattern could have occurred by random chance
If the scatter diagram shows no relationship between the variables consider whether
the data might be stratified
If the diagram shows no relationship consider whether the independent (x-axis)
variable has been varied widely Sometimes a relationship is not apparent because the
data donrsquot cover a wide enough range
Think creatively about how to use scatter diagrams to discover a root cause
Drawing a scatter diagram is the first step in looking for a relationship between
variables
22
7) Stratification
Stratification is a technique used in combination with other data analysis tools When
data from a variety of sources or categories have been lumped together the meaning
of the data can be impossible to see This technique separates the data so that patterns
can be seen
When to Use Stratification
Before collecting data
When data come from several sources or conditions such as shifts days of the
week suppliers or population groups
When data analysis may require separating different sources or conditions
Stratification Procedure
Before collecting data consider which information about the sources of the data
might have an effect on the results Set up the data collection so that you collect that
information as well
When plotting or graphing the collected data on a scatter diagram control chart
histogram or other analysis tool use different marks or colours to distinguish data
from various sources Data that are distinguished in this way are said to be
ldquostratifiedrdquo
Analyze the subsets of stratified data separately For example on a scatter diagram
where data are stratified into data from source 1 and data from source 2 draw
quadrants count points and determine the critical value only for the data from source
1 then only for the data from source 2
Stratification Example
23
The ZZndash400 manufacturing team drew a scatter diagram to test whether product
purity and iron contamination were related but the plot did not demonstrate a
relationship Then a team member realized that the data came from three different
reactors The team member redrew the diagram using a different symbol for each
reactorrsquos data
Now patterns can be seen The data from reactor 2 and reactor 3 are circled Even
without doing any calculations it is clear that for those two reactors purity decreases
as iron increases However the data from reactor 1 the solid dots that are not circled
do not show that relationship Something is different about reactor 1
Stratification Considerations
Here are examples of different sources that might require data to be stratified
Equipment
Shifts
Departments
24
Materials
Suppliers
Day of the week
Time of day
Products
Survey data usually benefit from stratification
Always consider before collecting data whether stratification might be needed during
analysis Plan to collect stratification information After the data are collected it might
be too late
On your graph or chart include a legend that identifies the marks or colours used
25
Now starting with new 7 quality control tool
Need of new quality control tool
Many customer requirements cannot always be adequately expressed by numerical
data alone Nevertheless even verbal statements can be expressions of facts because
it represents facts we ought to use Verbal data as well as numerical data in
controlling the managing quality It provides both quality control as well as
improvement during the manufacturing process
Benefits of new 7 quality control tool
Combine verbal with Numerical data
Looking for root cause
Clarify prioritize goals and schedule
Involve everyone into full cooperation and generate new ideas 1048577
The first new quality control tool is
1) Affinity Diagram
Application
An affinity diagram is used to organize into groupings large number of ideas opinions
or concerns about a Particular topic
Description
When a large number of ideas opinions or other concerns about a particular topic are
being collected this tool organizes the information into grouping~~based on the
natural relationships that exist among them The process is designed to stimulate
creativity and full participation It works best in groups of limited Size (a maximum
26
of eight members is recommended) in which members are accustomed to working
together This tool is often used to organize ideas generated by brainstorming
Procedure
State the topic to be studied in broad terms(details may prejudice the
response)
Record as many individual ideas opinions or concerns as possible on cards
(one per
card)
Mix the cards and spread them randomly on a large table
Group related cards together as follows
a)sort cards that seem to be related into groups and
b) limit number of grouping to ten without forcing single cards into groups
Locate or create a header card that captures the meaning of each group
Place this header card on top
Transfer the information from cards onto paper organized by groupings
Example For next generation digital camera we can organize the customer
Complains and requirements in an Affinity Diagram1048577
27
Affinity diagram
28
2) Tree diagram
Application
A tree diagram is used to show the interrelation between a topic and its component
elements
Description
A tree diagram systematically breaks down a topic into its component elements Ideas
generated by
Brainstorming and graphed or clustered with an affinity diagram can be converted
into a tree diagram
to show logical and sequential links This tool can be used in planning and problem
solving
Procedure
State the topic to be studied clearly
Define the major categories of the topic(brainstorm or use the header cards
from the affinity diagram)
Construct the diagram by placing the topic in a box on the left-hand side
Branch the major categories laterally to the right
For each major category define the component elements and sub-elements if
any
Laterally branch to the right the component elements and sub-elements for
each major category and
Review the diagram to ensure that there are no gaps in either sequence or
logic
29
30
3) Arrow diagram
Purpose To create a visual presentation of the steps of a process or tasks necessary to
complete a project with special emphasis on the time taken for these activities
Procedure
1 List all the tasks or activities needed to be accomplished before the process of the
project
2 Decide which steps are undertaken in series and which steps can be run in parallel
Arrange the
Activities in a proper sequence
3 Prepare lsquoEvent Nodesrsquo at the completion of steps and number them
4 Write the description of the step and decide the time required for completing each
step
5 Calculate the earliest time to reach an event node for the start of the process
7 Ager the time for all event nodes including the completion of the process or the
project is available one calculates the latest time by which an event node must be
reached
Application
The diagram is also useful in planning and scheduling steps in complicated processes
especially in planning and scheduling projects which involve a large number of
activities
Example
31
1 Identify the tasks Eg 123hellip15
2 Know the time each task needs
3 Determine which tasks can be run in parallel and in normal sequences
4 Draw the sequence diagram and find the critical path
5 Calculate the project duration
6 Calculate the earliest starting time (or the earliest finishing time of last task) and the
latest finishing time
of each task(the latest starting time for the following task)
7 Mark the time indication
32
33
4) Process Decision Program Chart (PDPC)
Def The process decision program chart (PDPC) method helps us select the best
processes to obtain optimum results by evaluating the progress of events and various
conceivable outcomes
Description
The process decision program chart (PDPC) method is used to define the solution
process when dealing with problems that have more than one possible outcome [t
anticipates the unexpected Outcomes at each stage and plans for it
PDPC has two following patterns
Pattern I ndash In this pattern process starts with initial condition lsquoArsquo and proceeds to the
desired final condition lsquoZrsquo in an organized manner
Pattern 11- In this pattern first the final conditionrsquosrsquo is set Then the process from lsquoZrsquo
to the initial point lsquoArsquo is developed with the inclusion of various alternatives from
many points of view
Procedure
Discuss the issues related to the project among a cross-functional team
Discuss which issues must be examined and identify those issues
Consider and note down all the anticipated results for the identified issues
Weigh the feasibility of each solution proposed and investigate alternate
solutions
Classify each issue according to its urgency number of operations required
likelihood of Occurrence and difficulty
Consider the anticipated results and alternative solutions related to issues that
must be addressed immediately and link the items with arrows to the desired
goal
34
Prioritize the different issues and consider them all together Information
related to one set of
Possibilities could influence another set Related items shall be linked with a
broken line
If the department that will handle a process involving several lines is
determined circle
the process and write the name of the department within
Set a target date for completion
Have regular meetings to check progress in terms of the original PDPC
35
36
37
38
5) Matrix diagram
Purpose1) Explore the existence and the extent of relations between individual items in 2 sets
of factors or features and characteristics and express them in a symbolic form that is
easy to understand
2) Mostly used to understand the relations between the customer expectations as
expressed by the customers and product characteristics as designed manufactured and
tested by the manufacturer
Procedures1 Determine 2 sets of factors for which the relations are needed to be established
2 Divide the features and characteristics into primary secondary and tertiary
characteristics
3 Place the features vertically on the leg side of the matrix and characteristics
horizontally on top of the matrix
4 Enter the importance of the features on the column ager that for the tertiary
features10485775 In the main body of the matrix use the symbols to represent the degree of
connections between the feature and characteristics
6 Choose and define relationship symbols Most commonly used symbols are as
given below
Strong relationship=
Relationship =
Likely relationship=
Application
bull Matrix diagram can be used to solve problems by arranging data in such a way that
the relations between relevant factors are brought into sharp focus
bull There is no limit to the use of the tool
39
bull The most important application of matrix diagram is in clarifying relations between
individual features of customer requirements and individual product characteristics
Example 1
Matrix Diagram for Quality Functions and Responsibilities
40
41
6) Matrix Data Analysis Diagram1048577
Purpose
To present numerical data about two sets of factors in a matrix form and
analyze it to get numerical output
Can be applied in understanding the products and products characteristics
Procedure1048577
1 Decide the two factors whose relations are to be analyzed
2 Check the number of individual items in the two factors
3 Prepare a matrix to accommodate all the items of the two factors
4 Enter numerical data in the matrix
5 Give the diagram a suitable title
Example
42
43
44
7) Relationship diagram
This diagram clarifies the interrelations in a complex situation involving many
interrelated factors and serves to clarify the cause and effect relationships among
factors
Description
Relations diagram is defined as a technique used to solve problems that have complex
cause and effect relationships among a number of problems and factors that influence
them
Format
A special feature of relation diagram is its unrestricted Format However general
formats are as given below
1) Centrally converging relations diagram
The major item or problem to be solved is located in the center and the related factors
are arranged around the item or problem in such a way as to indicate close
relationships
2) Directionally intensive relations diagram
The major item or problem to be solved is located on one side of the diagram and the
various factors arranged in accordance with the flow of their major cause-and-effect
relationships on the other side
3) Relationship indication relations diagram
There are no restrictions on this format because the main point is to arrange the cause-
and-effect Relationships of the application items or factors so that they are expressed
in a straightforward manner in a Diagram
45
Procedure
1) Define the issueproblem in such a way that it is clearly understood and agreed on
by team members
2) Assemble the cross-functional team
3) Layout all the ideasissue cards that have been brought from other tools
4) Look for causeinfluence relationships between all ideas and draw relationship
arrows
a) Choose any of the ideas as a starting point and work through them in sequence
b)An outgoing arrow from an idea indicates that it is the stronger cause or influence
c) Draw only one way relationship arrows in the direction of the stronger cause or
Influence Make a decision on the stronger direction Do not draw two headed arrows
5) Review and revise the relationsrsquo diagram
6) Tally the number of outgoing and incoming arrows and select key items for further
planning
-record and clearly mark next to each issue the number of arrows going in and out of
it
-find the items with the highest number outgoing arrows and the items with the
highest number of incoming arrows
-a high number of outgoing arrows indicate that the item is a root cause and should be
tackle first
46
-a high number of incoming arrows indicate that the item is a key outcome and may
become a focus for planning either as a meaningful measure of overall success or as a
redefinition of the original issue under discussion
Example
47
48
Conclusions
Statististical QC is chiefly concerned in making sure that several procedures
and working arrangements are in place to provide for effective and efficient
statistical processes to minimize the risk of errors or weaknesses in
procedures or systems or in source material
Seven QC tools are most helpful in troubleshooting issues related to quality
All processes are affected by multiple factors and therefore statistical QC tools
can be applied to any process
The continuous use of these tools upgrades the personnel characteristics of the
people involved It enhances their ability to think generate ideas solve
problem and do proper planning
49
References asqorglearn-about-qualityseven-basic-quality-toolsoverviewhtml
httpsenwikipediaorgwikiSeven_Basic_Tools_of_Quality
wwwijergsorgfilesdocumentsAPPLICATION-45pd
httpssrcalionsciencecompdfQualityToolspdf
www3haorghkqehwiserdoc7bqtpdf
wwwmathmunca~variyathNew7QCToolspd
50
- 1 DEFINITION of Quality Control
- 3 Competitiveness
- 4 Customer Loyalty
- 5 Reputation
- 6 Compliance
- 7 Costs
- Benefits of Using Quality Control in Manufacturing
-
17
6) Scatter chart
The scatter diagram graphs pairs of numerical data with one variable on each axis to
look for a relationship between them If the variables are correlated the points will
fall along a line or curve The better the correlation the tighter the points will hug the
line
When to Use a Scatter Diagram
When you have paired numerical data
When your dependent variable may have multiple values for each value of your
independent variable
When trying to determine whether the two variables are related such ashellip
When trying to identify potential root causes of problems
After brainstorming causes and effects using a fishbone diagram to determine
objectively whether a particular cause and effect are related
When determining whether two effects that appears to be related both occur with the
same cause
When testing for autocorrelation before constructing a control chart
Scatter Diagram Procedure
Collect pairs of data where a relationship is suspected
Draw a graph with the independent variable on the horizontal axis and the dependent
variable on the vertical axis For each pair of data put a dot or a symbol where the x-
axis value intersects the y-axis value (If two dots fall together put them side by side
touching so that you can see both)
18
Look at the pattern of points to see if a relationship is obvious If the data clearly form
a line or a curve you may stop The variables are correlated You may wish to use
regression or correlation analysis now Otherwise complete steps 4 through 7
Divide points on the graph into four quadrants If there are X points on the graph
Count X2 points from top to bottom and draw a horizontal line
Count X2 points from left to right and draw a vertical line
If number of points is odd draw the line through the middle point
Count the points in each quadrant Do not count points on a line
Add the diagonally opposite quadrants Find the smaller sum and the total of points in
all quadrants
A = points in upper left + points in lower right
B = points in upper right + points in lower left
Q = the smaller of A and B
N = A + B
Look up the limit for N on the trend test table
If Q is less than the limit the two variables are related
If Q is greater than or equal to the limit the pattern could have occurred from random
chance
19
Scatter Diagram Example
The ZZ-400 manufacturing team suspects a relationship between product purity
(percent purity) and the amount of iron (measured in parts per million or ppm) Purity
and iron are plotted against each other as a scatter diagram as shown in the figure
below
There are 24 data points Median lines are drawn so that 12 points fall on each side for
both percent purity and ppm iron
To test for a relationship they calculate
A = points in upper left + points in lower right = 9 + 9 = 18
B = points in upper right + points in lower left = 3 + 3 = 6
Q = the smaller of A and B = the smaller of 18 and 6 = 6
N = A + B = 18 + 6 = 24
20
Then they look up the limit for N on the trend test table For N = 24 the limit is 6
Q is equal to the limit Therefore the pattern could have occurred from random
chance and no relationship is demonstrated
Scatter Diagram Example
Scatter Diagram Considerations
Here are some examples of situations in which might you use a scatter diagram
Variable A is the temperature of a reaction after 15 minutes Variable B measures the
colour of the product You suspect higher temperature makes the product darker Plot
temperature and colour on a scatter diagram
Variable A is the number of employees trained on new software and variable B is the
number of calls to the computer helps line You suspect that more training reduces the
number of calls Plot number of people trained versus number of calls
To test for autocorrelation of a measurement being monitored on a control chart plot
this pair of variables Variable A is the measurement at a given time Variable B is the
same measurement but at the previous time If the scatter diagram shows correlation
do another diagram where variable B is the measurement two times previously Keep
increasing the separation between the two times until the scatter diagram shows no
correlation
21
Even if the scatter diagram shows a relationship do not assume that one variable
caused the other Both may be influenced by a third variable
When the data are plotted the more the diagram resembles a straight line the stronger
the relationship
If a line is not clear statistics (N and Q) determine whether there is reasonable
certainty that a relationship exists If the statistics say that no relationship exists the
pattern could have occurred by random chance
If the scatter diagram shows no relationship between the variables consider whether
the data might be stratified
If the diagram shows no relationship consider whether the independent (x-axis)
variable has been varied widely Sometimes a relationship is not apparent because the
data donrsquot cover a wide enough range
Think creatively about how to use scatter diagrams to discover a root cause
Drawing a scatter diagram is the first step in looking for a relationship between
variables
22
7) Stratification
Stratification is a technique used in combination with other data analysis tools When
data from a variety of sources or categories have been lumped together the meaning
of the data can be impossible to see This technique separates the data so that patterns
can be seen
When to Use Stratification
Before collecting data
When data come from several sources or conditions such as shifts days of the
week suppliers or population groups
When data analysis may require separating different sources or conditions
Stratification Procedure
Before collecting data consider which information about the sources of the data
might have an effect on the results Set up the data collection so that you collect that
information as well
When plotting or graphing the collected data on a scatter diagram control chart
histogram or other analysis tool use different marks or colours to distinguish data
from various sources Data that are distinguished in this way are said to be
ldquostratifiedrdquo
Analyze the subsets of stratified data separately For example on a scatter diagram
where data are stratified into data from source 1 and data from source 2 draw
quadrants count points and determine the critical value only for the data from source
1 then only for the data from source 2
Stratification Example
23
The ZZndash400 manufacturing team drew a scatter diagram to test whether product
purity and iron contamination were related but the plot did not demonstrate a
relationship Then a team member realized that the data came from three different
reactors The team member redrew the diagram using a different symbol for each
reactorrsquos data
Now patterns can be seen The data from reactor 2 and reactor 3 are circled Even
without doing any calculations it is clear that for those two reactors purity decreases
as iron increases However the data from reactor 1 the solid dots that are not circled
do not show that relationship Something is different about reactor 1
Stratification Considerations
Here are examples of different sources that might require data to be stratified
Equipment
Shifts
Departments
24
Materials
Suppliers
Day of the week
Time of day
Products
Survey data usually benefit from stratification
Always consider before collecting data whether stratification might be needed during
analysis Plan to collect stratification information After the data are collected it might
be too late
On your graph or chart include a legend that identifies the marks or colours used
25
Now starting with new 7 quality control tool
Need of new quality control tool
Many customer requirements cannot always be adequately expressed by numerical
data alone Nevertheless even verbal statements can be expressions of facts because
it represents facts we ought to use Verbal data as well as numerical data in
controlling the managing quality It provides both quality control as well as
improvement during the manufacturing process
Benefits of new 7 quality control tool
Combine verbal with Numerical data
Looking for root cause
Clarify prioritize goals and schedule
Involve everyone into full cooperation and generate new ideas 1048577
The first new quality control tool is
1) Affinity Diagram
Application
An affinity diagram is used to organize into groupings large number of ideas opinions
or concerns about a Particular topic
Description
When a large number of ideas opinions or other concerns about a particular topic are
being collected this tool organizes the information into grouping~~based on the
natural relationships that exist among them The process is designed to stimulate
creativity and full participation It works best in groups of limited Size (a maximum
26
of eight members is recommended) in which members are accustomed to working
together This tool is often used to organize ideas generated by brainstorming
Procedure
State the topic to be studied in broad terms(details may prejudice the
response)
Record as many individual ideas opinions or concerns as possible on cards
(one per
card)
Mix the cards and spread them randomly on a large table
Group related cards together as follows
a)sort cards that seem to be related into groups and
b) limit number of grouping to ten without forcing single cards into groups
Locate or create a header card that captures the meaning of each group
Place this header card on top
Transfer the information from cards onto paper organized by groupings
Example For next generation digital camera we can organize the customer
Complains and requirements in an Affinity Diagram1048577
27
Affinity diagram
28
2) Tree diagram
Application
A tree diagram is used to show the interrelation between a topic and its component
elements
Description
A tree diagram systematically breaks down a topic into its component elements Ideas
generated by
Brainstorming and graphed or clustered with an affinity diagram can be converted
into a tree diagram
to show logical and sequential links This tool can be used in planning and problem
solving
Procedure
State the topic to be studied clearly
Define the major categories of the topic(brainstorm or use the header cards
from the affinity diagram)
Construct the diagram by placing the topic in a box on the left-hand side
Branch the major categories laterally to the right
For each major category define the component elements and sub-elements if
any
Laterally branch to the right the component elements and sub-elements for
each major category and
Review the diagram to ensure that there are no gaps in either sequence or
logic
29
30
3) Arrow diagram
Purpose To create a visual presentation of the steps of a process or tasks necessary to
complete a project with special emphasis on the time taken for these activities
Procedure
1 List all the tasks or activities needed to be accomplished before the process of the
project
2 Decide which steps are undertaken in series and which steps can be run in parallel
Arrange the
Activities in a proper sequence
3 Prepare lsquoEvent Nodesrsquo at the completion of steps and number them
4 Write the description of the step and decide the time required for completing each
step
5 Calculate the earliest time to reach an event node for the start of the process
7 Ager the time for all event nodes including the completion of the process or the
project is available one calculates the latest time by which an event node must be
reached
Application
The diagram is also useful in planning and scheduling steps in complicated processes
especially in planning and scheduling projects which involve a large number of
activities
Example
31
1 Identify the tasks Eg 123hellip15
2 Know the time each task needs
3 Determine which tasks can be run in parallel and in normal sequences
4 Draw the sequence diagram and find the critical path
5 Calculate the project duration
6 Calculate the earliest starting time (or the earliest finishing time of last task) and the
latest finishing time
of each task(the latest starting time for the following task)
7 Mark the time indication
32
33
4) Process Decision Program Chart (PDPC)
Def The process decision program chart (PDPC) method helps us select the best
processes to obtain optimum results by evaluating the progress of events and various
conceivable outcomes
Description
The process decision program chart (PDPC) method is used to define the solution
process when dealing with problems that have more than one possible outcome [t
anticipates the unexpected Outcomes at each stage and plans for it
PDPC has two following patterns
Pattern I ndash In this pattern process starts with initial condition lsquoArsquo and proceeds to the
desired final condition lsquoZrsquo in an organized manner
Pattern 11- In this pattern first the final conditionrsquosrsquo is set Then the process from lsquoZrsquo
to the initial point lsquoArsquo is developed with the inclusion of various alternatives from
many points of view
Procedure
Discuss the issues related to the project among a cross-functional team
Discuss which issues must be examined and identify those issues
Consider and note down all the anticipated results for the identified issues
Weigh the feasibility of each solution proposed and investigate alternate
solutions
Classify each issue according to its urgency number of operations required
likelihood of Occurrence and difficulty
Consider the anticipated results and alternative solutions related to issues that
must be addressed immediately and link the items with arrows to the desired
goal
34
Prioritize the different issues and consider them all together Information
related to one set of
Possibilities could influence another set Related items shall be linked with a
broken line
If the department that will handle a process involving several lines is
determined circle
the process and write the name of the department within
Set a target date for completion
Have regular meetings to check progress in terms of the original PDPC
35
36
37
38
5) Matrix diagram
Purpose1) Explore the existence and the extent of relations between individual items in 2 sets
of factors or features and characteristics and express them in a symbolic form that is
easy to understand
2) Mostly used to understand the relations between the customer expectations as
expressed by the customers and product characteristics as designed manufactured and
tested by the manufacturer
Procedures1 Determine 2 sets of factors for which the relations are needed to be established
2 Divide the features and characteristics into primary secondary and tertiary
characteristics
3 Place the features vertically on the leg side of the matrix and characteristics
horizontally on top of the matrix
4 Enter the importance of the features on the column ager that for the tertiary
features10485775 In the main body of the matrix use the symbols to represent the degree of
connections between the feature and characteristics
6 Choose and define relationship symbols Most commonly used symbols are as
given below
Strong relationship=
Relationship =
Likely relationship=
Application
bull Matrix diagram can be used to solve problems by arranging data in such a way that
the relations between relevant factors are brought into sharp focus
bull There is no limit to the use of the tool
39
bull The most important application of matrix diagram is in clarifying relations between
individual features of customer requirements and individual product characteristics
Example 1
Matrix Diagram for Quality Functions and Responsibilities
40
41
6) Matrix Data Analysis Diagram1048577
Purpose
To present numerical data about two sets of factors in a matrix form and
analyze it to get numerical output
Can be applied in understanding the products and products characteristics
Procedure1048577
1 Decide the two factors whose relations are to be analyzed
2 Check the number of individual items in the two factors
3 Prepare a matrix to accommodate all the items of the two factors
4 Enter numerical data in the matrix
5 Give the diagram a suitable title
Example
42
43
44
7) Relationship diagram
This diagram clarifies the interrelations in a complex situation involving many
interrelated factors and serves to clarify the cause and effect relationships among
factors
Description
Relations diagram is defined as a technique used to solve problems that have complex
cause and effect relationships among a number of problems and factors that influence
them
Format
A special feature of relation diagram is its unrestricted Format However general
formats are as given below
1) Centrally converging relations diagram
The major item or problem to be solved is located in the center and the related factors
are arranged around the item or problem in such a way as to indicate close
relationships
2) Directionally intensive relations diagram
The major item or problem to be solved is located on one side of the diagram and the
various factors arranged in accordance with the flow of their major cause-and-effect
relationships on the other side
3) Relationship indication relations diagram
There are no restrictions on this format because the main point is to arrange the cause-
and-effect Relationships of the application items or factors so that they are expressed
in a straightforward manner in a Diagram
45
Procedure
1) Define the issueproblem in such a way that it is clearly understood and agreed on
by team members
2) Assemble the cross-functional team
3) Layout all the ideasissue cards that have been brought from other tools
4) Look for causeinfluence relationships between all ideas and draw relationship
arrows
a) Choose any of the ideas as a starting point and work through them in sequence
b)An outgoing arrow from an idea indicates that it is the stronger cause or influence
c) Draw only one way relationship arrows in the direction of the stronger cause or
Influence Make a decision on the stronger direction Do not draw two headed arrows
5) Review and revise the relationsrsquo diagram
6) Tally the number of outgoing and incoming arrows and select key items for further
planning
-record and clearly mark next to each issue the number of arrows going in and out of
it
-find the items with the highest number outgoing arrows and the items with the
highest number of incoming arrows
-a high number of outgoing arrows indicate that the item is a root cause and should be
tackle first
46
-a high number of incoming arrows indicate that the item is a key outcome and may
become a focus for planning either as a meaningful measure of overall success or as a
redefinition of the original issue under discussion
Example
47
48
Conclusions
Statististical QC is chiefly concerned in making sure that several procedures
and working arrangements are in place to provide for effective and efficient
statistical processes to minimize the risk of errors or weaknesses in
procedures or systems or in source material
Seven QC tools are most helpful in troubleshooting issues related to quality
All processes are affected by multiple factors and therefore statistical QC tools
can be applied to any process
The continuous use of these tools upgrades the personnel characteristics of the
people involved It enhances their ability to think generate ideas solve
problem and do proper planning
49
References asqorglearn-about-qualityseven-basic-quality-toolsoverviewhtml
httpsenwikipediaorgwikiSeven_Basic_Tools_of_Quality
wwwijergsorgfilesdocumentsAPPLICATION-45pd
httpssrcalionsciencecompdfQualityToolspdf
www3haorghkqehwiserdoc7bqtpdf
wwwmathmunca~variyathNew7QCToolspd
50
- 1 DEFINITION of Quality Control
- 3 Competitiveness
- 4 Customer Loyalty
- 5 Reputation
- 6 Compliance
- 7 Costs
- Benefits of Using Quality Control in Manufacturing
-
6) Scatter chart
The scatter diagram graphs pairs of numerical data with one variable on each axis to
look for a relationship between them If the variables are correlated the points will
fall along a line or curve The better the correlation the tighter the points will hug the
line
When to Use a Scatter Diagram
When you have paired numerical data
When your dependent variable may have multiple values for each value of your
independent variable
When trying to determine whether the two variables are related such ashellip
When trying to identify potential root causes of problems
After brainstorming causes and effects using a fishbone diagram to determine
objectively whether a particular cause and effect are related
When determining whether two effects that appears to be related both occur with the
same cause
When testing for autocorrelation before constructing a control chart
Scatter Diagram Procedure
Collect pairs of data where a relationship is suspected
Draw a graph with the independent variable on the horizontal axis and the dependent
variable on the vertical axis For each pair of data put a dot or a symbol where the x-
axis value intersects the y-axis value (If two dots fall together put them side by side
touching so that you can see both)
18
Look at the pattern of points to see if a relationship is obvious If the data clearly form
a line or a curve you may stop The variables are correlated You may wish to use
regression or correlation analysis now Otherwise complete steps 4 through 7
Divide points on the graph into four quadrants If there are X points on the graph
Count X2 points from top to bottom and draw a horizontal line
Count X2 points from left to right and draw a vertical line
If number of points is odd draw the line through the middle point
Count the points in each quadrant Do not count points on a line
Add the diagonally opposite quadrants Find the smaller sum and the total of points in
all quadrants
A = points in upper left + points in lower right
B = points in upper right + points in lower left
Q = the smaller of A and B
N = A + B
Look up the limit for N on the trend test table
If Q is less than the limit the two variables are related
If Q is greater than or equal to the limit the pattern could have occurred from random
chance
19
Scatter Diagram Example
The ZZ-400 manufacturing team suspects a relationship between product purity
(percent purity) and the amount of iron (measured in parts per million or ppm) Purity
and iron are plotted against each other as a scatter diagram as shown in the figure
below
There are 24 data points Median lines are drawn so that 12 points fall on each side for
both percent purity and ppm iron
To test for a relationship they calculate
A = points in upper left + points in lower right = 9 + 9 = 18
B = points in upper right + points in lower left = 3 + 3 = 6
Q = the smaller of A and B = the smaller of 18 and 6 = 6
N = A + B = 18 + 6 = 24
20
Then they look up the limit for N on the trend test table For N = 24 the limit is 6
Q is equal to the limit Therefore the pattern could have occurred from random
chance and no relationship is demonstrated
Scatter Diagram Example
Scatter Diagram Considerations
Here are some examples of situations in which might you use a scatter diagram
Variable A is the temperature of a reaction after 15 minutes Variable B measures the
colour of the product You suspect higher temperature makes the product darker Plot
temperature and colour on a scatter diagram
Variable A is the number of employees trained on new software and variable B is the
number of calls to the computer helps line You suspect that more training reduces the
number of calls Plot number of people trained versus number of calls
To test for autocorrelation of a measurement being monitored on a control chart plot
this pair of variables Variable A is the measurement at a given time Variable B is the
same measurement but at the previous time If the scatter diagram shows correlation
do another diagram where variable B is the measurement two times previously Keep
increasing the separation between the two times until the scatter diagram shows no
correlation
21
Even if the scatter diagram shows a relationship do not assume that one variable
caused the other Both may be influenced by a third variable
When the data are plotted the more the diagram resembles a straight line the stronger
the relationship
If a line is not clear statistics (N and Q) determine whether there is reasonable
certainty that a relationship exists If the statistics say that no relationship exists the
pattern could have occurred by random chance
If the scatter diagram shows no relationship between the variables consider whether
the data might be stratified
If the diagram shows no relationship consider whether the independent (x-axis)
variable has been varied widely Sometimes a relationship is not apparent because the
data donrsquot cover a wide enough range
Think creatively about how to use scatter diagrams to discover a root cause
Drawing a scatter diagram is the first step in looking for a relationship between
variables
22
7) Stratification
Stratification is a technique used in combination with other data analysis tools When
data from a variety of sources or categories have been lumped together the meaning
of the data can be impossible to see This technique separates the data so that patterns
can be seen
When to Use Stratification
Before collecting data
When data come from several sources or conditions such as shifts days of the
week suppliers or population groups
When data analysis may require separating different sources or conditions
Stratification Procedure
Before collecting data consider which information about the sources of the data
might have an effect on the results Set up the data collection so that you collect that
information as well
When plotting or graphing the collected data on a scatter diagram control chart
histogram or other analysis tool use different marks or colours to distinguish data
from various sources Data that are distinguished in this way are said to be
ldquostratifiedrdquo
Analyze the subsets of stratified data separately For example on a scatter diagram
where data are stratified into data from source 1 and data from source 2 draw
quadrants count points and determine the critical value only for the data from source
1 then only for the data from source 2
Stratification Example
23
The ZZndash400 manufacturing team drew a scatter diagram to test whether product
purity and iron contamination were related but the plot did not demonstrate a
relationship Then a team member realized that the data came from three different
reactors The team member redrew the diagram using a different symbol for each
reactorrsquos data
Now patterns can be seen The data from reactor 2 and reactor 3 are circled Even
without doing any calculations it is clear that for those two reactors purity decreases
as iron increases However the data from reactor 1 the solid dots that are not circled
do not show that relationship Something is different about reactor 1
Stratification Considerations
Here are examples of different sources that might require data to be stratified
Equipment
Shifts
Departments
24
Materials
Suppliers
Day of the week
Time of day
Products
Survey data usually benefit from stratification
Always consider before collecting data whether stratification might be needed during
analysis Plan to collect stratification information After the data are collected it might
be too late
On your graph or chart include a legend that identifies the marks or colours used
25
Now starting with new 7 quality control tool
Need of new quality control tool
Many customer requirements cannot always be adequately expressed by numerical
data alone Nevertheless even verbal statements can be expressions of facts because
it represents facts we ought to use Verbal data as well as numerical data in
controlling the managing quality It provides both quality control as well as
improvement during the manufacturing process
Benefits of new 7 quality control tool
Combine verbal with Numerical data
Looking for root cause
Clarify prioritize goals and schedule
Involve everyone into full cooperation and generate new ideas 1048577
The first new quality control tool is
1) Affinity Diagram
Application
An affinity diagram is used to organize into groupings large number of ideas opinions
or concerns about a Particular topic
Description
When a large number of ideas opinions or other concerns about a particular topic are
being collected this tool organizes the information into grouping~~based on the
natural relationships that exist among them The process is designed to stimulate
creativity and full participation It works best in groups of limited Size (a maximum
26
of eight members is recommended) in which members are accustomed to working
together This tool is often used to organize ideas generated by brainstorming
Procedure
State the topic to be studied in broad terms(details may prejudice the
response)
Record as many individual ideas opinions or concerns as possible on cards
(one per
card)
Mix the cards and spread them randomly on a large table
Group related cards together as follows
a)sort cards that seem to be related into groups and
b) limit number of grouping to ten without forcing single cards into groups
Locate or create a header card that captures the meaning of each group
Place this header card on top
Transfer the information from cards onto paper organized by groupings
Example For next generation digital camera we can organize the customer
Complains and requirements in an Affinity Diagram1048577
27
Affinity diagram
28
2) Tree diagram
Application
A tree diagram is used to show the interrelation between a topic and its component
elements
Description
A tree diagram systematically breaks down a topic into its component elements Ideas
generated by
Brainstorming and graphed or clustered with an affinity diagram can be converted
into a tree diagram
to show logical and sequential links This tool can be used in planning and problem
solving
Procedure
State the topic to be studied clearly
Define the major categories of the topic(brainstorm or use the header cards
from the affinity diagram)
Construct the diagram by placing the topic in a box on the left-hand side
Branch the major categories laterally to the right
For each major category define the component elements and sub-elements if
any
Laterally branch to the right the component elements and sub-elements for
each major category and
Review the diagram to ensure that there are no gaps in either sequence or
logic
29
30
3) Arrow diagram
Purpose To create a visual presentation of the steps of a process or tasks necessary to
complete a project with special emphasis on the time taken for these activities
Procedure
1 List all the tasks or activities needed to be accomplished before the process of the
project
2 Decide which steps are undertaken in series and which steps can be run in parallel
Arrange the
Activities in a proper sequence
3 Prepare lsquoEvent Nodesrsquo at the completion of steps and number them
4 Write the description of the step and decide the time required for completing each
step
5 Calculate the earliest time to reach an event node for the start of the process
7 Ager the time for all event nodes including the completion of the process or the
project is available one calculates the latest time by which an event node must be
reached
Application
The diagram is also useful in planning and scheduling steps in complicated processes
especially in planning and scheduling projects which involve a large number of
activities
Example
31
1 Identify the tasks Eg 123hellip15
2 Know the time each task needs
3 Determine which tasks can be run in parallel and in normal sequences
4 Draw the sequence diagram and find the critical path
5 Calculate the project duration
6 Calculate the earliest starting time (or the earliest finishing time of last task) and the
latest finishing time
of each task(the latest starting time for the following task)
7 Mark the time indication
32
33
4) Process Decision Program Chart (PDPC)
Def The process decision program chart (PDPC) method helps us select the best
processes to obtain optimum results by evaluating the progress of events and various
conceivable outcomes
Description
The process decision program chart (PDPC) method is used to define the solution
process when dealing with problems that have more than one possible outcome [t
anticipates the unexpected Outcomes at each stage and plans for it
PDPC has two following patterns
Pattern I ndash In this pattern process starts with initial condition lsquoArsquo and proceeds to the
desired final condition lsquoZrsquo in an organized manner
Pattern 11- In this pattern first the final conditionrsquosrsquo is set Then the process from lsquoZrsquo
to the initial point lsquoArsquo is developed with the inclusion of various alternatives from
many points of view
Procedure
Discuss the issues related to the project among a cross-functional team
Discuss which issues must be examined and identify those issues
Consider and note down all the anticipated results for the identified issues
Weigh the feasibility of each solution proposed and investigate alternate
solutions
Classify each issue according to its urgency number of operations required
likelihood of Occurrence and difficulty
Consider the anticipated results and alternative solutions related to issues that
must be addressed immediately and link the items with arrows to the desired
goal
34
Prioritize the different issues and consider them all together Information
related to one set of
Possibilities could influence another set Related items shall be linked with a
broken line
If the department that will handle a process involving several lines is
determined circle
the process and write the name of the department within
Set a target date for completion
Have regular meetings to check progress in terms of the original PDPC
35
36
37
38
5) Matrix diagram
Purpose1) Explore the existence and the extent of relations between individual items in 2 sets
of factors or features and characteristics and express them in a symbolic form that is
easy to understand
2) Mostly used to understand the relations between the customer expectations as
expressed by the customers and product characteristics as designed manufactured and
tested by the manufacturer
Procedures1 Determine 2 sets of factors for which the relations are needed to be established
2 Divide the features and characteristics into primary secondary and tertiary
characteristics
3 Place the features vertically on the leg side of the matrix and characteristics
horizontally on top of the matrix
4 Enter the importance of the features on the column ager that for the tertiary
features10485775 In the main body of the matrix use the symbols to represent the degree of
connections between the feature and characteristics
6 Choose and define relationship symbols Most commonly used symbols are as
given below
Strong relationship=
Relationship =
Likely relationship=
Application
bull Matrix diagram can be used to solve problems by arranging data in such a way that
the relations between relevant factors are brought into sharp focus
bull There is no limit to the use of the tool
39
bull The most important application of matrix diagram is in clarifying relations between
individual features of customer requirements and individual product characteristics
Example 1
Matrix Diagram for Quality Functions and Responsibilities
40
41
6) Matrix Data Analysis Diagram1048577
Purpose
To present numerical data about two sets of factors in a matrix form and
analyze it to get numerical output
Can be applied in understanding the products and products characteristics
Procedure1048577
1 Decide the two factors whose relations are to be analyzed
2 Check the number of individual items in the two factors
3 Prepare a matrix to accommodate all the items of the two factors
4 Enter numerical data in the matrix
5 Give the diagram a suitable title
Example
42
43
44
7) Relationship diagram
This diagram clarifies the interrelations in a complex situation involving many
interrelated factors and serves to clarify the cause and effect relationships among
factors
Description
Relations diagram is defined as a technique used to solve problems that have complex
cause and effect relationships among a number of problems and factors that influence
them
Format
A special feature of relation diagram is its unrestricted Format However general
formats are as given below
1) Centrally converging relations diagram
The major item or problem to be solved is located in the center and the related factors
are arranged around the item or problem in such a way as to indicate close
relationships
2) Directionally intensive relations diagram
The major item or problem to be solved is located on one side of the diagram and the
various factors arranged in accordance with the flow of their major cause-and-effect
relationships on the other side
3) Relationship indication relations diagram
There are no restrictions on this format because the main point is to arrange the cause-
and-effect Relationships of the application items or factors so that they are expressed
in a straightforward manner in a Diagram
45
Procedure
1) Define the issueproblem in such a way that it is clearly understood and agreed on
by team members
2) Assemble the cross-functional team
3) Layout all the ideasissue cards that have been brought from other tools
4) Look for causeinfluence relationships between all ideas and draw relationship
arrows
a) Choose any of the ideas as a starting point and work through them in sequence
b)An outgoing arrow from an idea indicates that it is the stronger cause or influence
c) Draw only one way relationship arrows in the direction of the stronger cause or
Influence Make a decision on the stronger direction Do not draw two headed arrows
5) Review and revise the relationsrsquo diagram
6) Tally the number of outgoing and incoming arrows and select key items for further
planning
-record and clearly mark next to each issue the number of arrows going in and out of
it
-find the items with the highest number outgoing arrows and the items with the
highest number of incoming arrows
-a high number of outgoing arrows indicate that the item is a root cause and should be
tackle first
46
-a high number of incoming arrows indicate that the item is a key outcome and may
become a focus for planning either as a meaningful measure of overall success or as a
redefinition of the original issue under discussion
Example
47
48
Conclusions
Statististical QC is chiefly concerned in making sure that several procedures
and working arrangements are in place to provide for effective and efficient
statistical processes to minimize the risk of errors or weaknesses in
procedures or systems or in source material
Seven QC tools are most helpful in troubleshooting issues related to quality
All processes are affected by multiple factors and therefore statistical QC tools
can be applied to any process
The continuous use of these tools upgrades the personnel characteristics of the
people involved It enhances their ability to think generate ideas solve
problem and do proper planning
49
References asqorglearn-about-qualityseven-basic-quality-toolsoverviewhtml
httpsenwikipediaorgwikiSeven_Basic_Tools_of_Quality
wwwijergsorgfilesdocumentsAPPLICATION-45pd
httpssrcalionsciencecompdfQualityToolspdf
www3haorghkqehwiserdoc7bqtpdf
wwwmathmunca~variyathNew7QCToolspd
50
- 1 DEFINITION of Quality Control
- 3 Competitiveness
- 4 Customer Loyalty
- 5 Reputation
- 6 Compliance
- 7 Costs
- Benefits of Using Quality Control in Manufacturing
-
Look at the pattern of points to see if a relationship is obvious If the data clearly form
a line or a curve you may stop The variables are correlated You may wish to use
regression or correlation analysis now Otherwise complete steps 4 through 7
Divide points on the graph into four quadrants If there are X points on the graph
Count X2 points from top to bottom and draw a horizontal line
Count X2 points from left to right and draw a vertical line
If number of points is odd draw the line through the middle point
Count the points in each quadrant Do not count points on a line
Add the diagonally opposite quadrants Find the smaller sum and the total of points in
all quadrants
A = points in upper left + points in lower right
B = points in upper right + points in lower left
Q = the smaller of A and B
N = A + B
Look up the limit for N on the trend test table
If Q is less than the limit the two variables are related
If Q is greater than or equal to the limit the pattern could have occurred from random
chance
19
Scatter Diagram Example
The ZZ-400 manufacturing team suspects a relationship between product purity
(percent purity) and the amount of iron (measured in parts per million or ppm) Purity
and iron are plotted against each other as a scatter diagram as shown in the figure
below
There are 24 data points Median lines are drawn so that 12 points fall on each side for
both percent purity and ppm iron
To test for a relationship they calculate
A = points in upper left + points in lower right = 9 + 9 = 18
B = points in upper right + points in lower left = 3 + 3 = 6
Q = the smaller of A and B = the smaller of 18 and 6 = 6
N = A + B = 18 + 6 = 24
20
Then they look up the limit for N on the trend test table For N = 24 the limit is 6
Q is equal to the limit Therefore the pattern could have occurred from random
chance and no relationship is demonstrated
Scatter Diagram Example
Scatter Diagram Considerations
Here are some examples of situations in which might you use a scatter diagram
Variable A is the temperature of a reaction after 15 minutes Variable B measures the
colour of the product You suspect higher temperature makes the product darker Plot
temperature and colour on a scatter diagram
Variable A is the number of employees trained on new software and variable B is the
number of calls to the computer helps line You suspect that more training reduces the
number of calls Plot number of people trained versus number of calls
To test for autocorrelation of a measurement being monitored on a control chart plot
this pair of variables Variable A is the measurement at a given time Variable B is the
same measurement but at the previous time If the scatter diagram shows correlation
do another diagram where variable B is the measurement two times previously Keep
increasing the separation between the two times until the scatter diagram shows no
correlation
21
Even if the scatter diagram shows a relationship do not assume that one variable
caused the other Both may be influenced by a third variable
When the data are plotted the more the diagram resembles a straight line the stronger
the relationship
If a line is not clear statistics (N and Q) determine whether there is reasonable
certainty that a relationship exists If the statistics say that no relationship exists the
pattern could have occurred by random chance
If the scatter diagram shows no relationship between the variables consider whether
the data might be stratified
If the diagram shows no relationship consider whether the independent (x-axis)
variable has been varied widely Sometimes a relationship is not apparent because the
data donrsquot cover a wide enough range
Think creatively about how to use scatter diagrams to discover a root cause
Drawing a scatter diagram is the first step in looking for a relationship between
variables
22
7) Stratification
Stratification is a technique used in combination with other data analysis tools When
data from a variety of sources or categories have been lumped together the meaning
of the data can be impossible to see This technique separates the data so that patterns
can be seen
When to Use Stratification
Before collecting data
When data come from several sources or conditions such as shifts days of the
week suppliers or population groups
When data analysis may require separating different sources or conditions
Stratification Procedure
Before collecting data consider which information about the sources of the data
might have an effect on the results Set up the data collection so that you collect that
information as well
When plotting or graphing the collected data on a scatter diagram control chart
histogram or other analysis tool use different marks or colours to distinguish data
from various sources Data that are distinguished in this way are said to be
ldquostratifiedrdquo
Analyze the subsets of stratified data separately For example on a scatter diagram
where data are stratified into data from source 1 and data from source 2 draw
quadrants count points and determine the critical value only for the data from source
1 then only for the data from source 2
Stratification Example
23
The ZZndash400 manufacturing team drew a scatter diagram to test whether product
purity and iron contamination were related but the plot did not demonstrate a
relationship Then a team member realized that the data came from three different
reactors The team member redrew the diagram using a different symbol for each
reactorrsquos data
Now patterns can be seen The data from reactor 2 and reactor 3 are circled Even
without doing any calculations it is clear that for those two reactors purity decreases
as iron increases However the data from reactor 1 the solid dots that are not circled
do not show that relationship Something is different about reactor 1
Stratification Considerations
Here are examples of different sources that might require data to be stratified
Equipment
Shifts
Departments
24
Materials
Suppliers
Day of the week
Time of day
Products
Survey data usually benefit from stratification
Always consider before collecting data whether stratification might be needed during
analysis Plan to collect stratification information After the data are collected it might
be too late
On your graph or chart include a legend that identifies the marks or colours used
25
Now starting with new 7 quality control tool
Need of new quality control tool
Many customer requirements cannot always be adequately expressed by numerical
data alone Nevertheless even verbal statements can be expressions of facts because
it represents facts we ought to use Verbal data as well as numerical data in
controlling the managing quality It provides both quality control as well as
improvement during the manufacturing process
Benefits of new 7 quality control tool
Combine verbal with Numerical data
Looking for root cause
Clarify prioritize goals and schedule
Involve everyone into full cooperation and generate new ideas 1048577
The first new quality control tool is
1) Affinity Diagram
Application
An affinity diagram is used to organize into groupings large number of ideas opinions
or concerns about a Particular topic
Description
When a large number of ideas opinions or other concerns about a particular topic are
being collected this tool organizes the information into grouping~~based on the
natural relationships that exist among them The process is designed to stimulate
creativity and full participation It works best in groups of limited Size (a maximum
26
of eight members is recommended) in which members are accustomed to working
together This tool is often used to organize ideas generated by brainstorming
Procedure
State the topic to be studied in broad terms(details may prejudice the
response)
Record as many individual ideas opinions or concerns as possible on cards
(one per
card)
Mix the cards and spread them randomly on a large table
Group related cards together as follows
a)sort cards that seem to be related into groups and
b) limit number of grouping to ten without forcing single cards into groups
Locate or create a header card that captures the meaning of each group
Place this header card on top
Transfer the information from cards onto paper organized by groupings
Example For next generation digital camera we can organize the customer
Complains and requirements in an Affinity Diagram1048577
27
Affinity diagram
28
2) Tree diagram
Application
A tree diagram is used to show the interrelation between a topic and its component
elements
Description
A tree diagram systematically breaks down a topic into its component elements Ideas
generated by
Brainstorming and graphed or clustered with an affinity diagram can be converted
into a tree diagram
to show logical and sequential links This tool can be used in planning and problem
solving
Procedure
State the topic to be studied clearly
Define the major categories of the topic(brainstorm or use the header cards
from the affinity diagram)
Construct the diagram by placing the topic in a box on the left-hand side
Branch the major categories laterally to the right
For each major category define the component elements and sub-elements if
any
Laterally branch to the right the component elements and sub-elements for
each major category and
Review the diagram to ensure that there are no gaps in either sequence or
logic
29
30
3) Arrow diagram
Purpose To create a visual presentation of the steps of a process or tasks necessary to
complete a project with special emphasis on the time taken for these activities
Procedure
1 List all the tasks or activities needed to be accomplished before the process of the
project
2 Decide which steps are undertaken in series and which steps can be run in parallel
Arrange the
Activities in a proper sequence
3 Prepare lsquoEvent Nodesrsquo at the completion of steps and number them
4 Write the description of the step and decide the time required for completing each
step
5 Calculate the earliest time to reach an event node for the start of the process
7 Ager the time for all event nodes including the completion of the process or the
project is available one calculates the latest time by which an event node must be
reached
Application
The diagram is also useful in planning and scheduling steps in complicated processes
especially in planning and scheduling projects which involve a large number of
activities
Example
31
1 Identify the tasks Eg 123hellip15
2 Know the time each task needs
3 Determine which tasks can be run in parallel and in normal sequences
4 Draw the sequence diagram and find the critical path
5 Calculate the project duration
6 Calculate the earliest starting time (or the earliest finishing time of last task) and the
latest finishing time
of each task(the latest starting time for the following task)
7 Mark the time indication
32
33
4) Process Decision Program Chart (PDPC)
Def The process decision program chart (PDPC) method helps us select the best
processes to obtain optimum results by evaluating the progress of events and various
conceivable outcomes
Description
The process decision program chart (PDPC) method is used to define the solution
process when dealing with problems that have more than one possible outcome [t
anticipates the unexpected Outcomes at each stage and plans for it
PDPC has two following patterns
Pattern I ndash In this pattern process starts with initial condition lsquoArsquo and proceeds to the
desired final condition lsquoZrsquo in an organized manner
Pattern 11- In this pattern first the final conditionrsquosrsquo is set Then the process from lsquoZrsquo
to the initial point lsquoArsquo is developed with the inclusion of various alternatives from
many points of view
Procedure
Discuss the issues related to the project among a cross-functional team
Discuss which issues must be examined and identify those issues
Consider and note down all the anticipated results for the identified issues
Weigh the feasibility of each solution proposed and investigate alternate
solutions
Classify each issue according to its urgency number of operations required
likelihood of Occurrence and difficulty
Consider the anticipated results and alternative solutions related to issues that
must be addressed immediately and link the items with arrows to the desired
goal
34
Prioritize the different issues and consider them all together Information
related to one set of
Possibilities could influence another set Related items shall be linked with a
broken line
If the department that will handle a process involving several lines is
determined circle
the process and write the name of the department within
Set a target date for completion
Have regular meetings to check progress in terms of the original PDPC
35
36
37
38
5) Matrix diagram
Purpose1) Explore the existence and the extent of relations between individual items in 2 sets
of factors or features and characteristics and express them in a symbolic form that is
easy to understand
2) Mostly used to understand the relations between the customer expectations as
expressed by the customers and product characteristics as designed manufactured and
tested by the manufacturer
Procedures1 Determine 2 sets of factors for which the relations are needed to be established
2 Divide the features and characteristics into primary secondary and tertiary
characteristics
3 Place the features vertically on the leg side of the matrix and characteristics
horizontally on top of the matrix
4 Enter the importance of the features on the column ager that for the tertiary
features10485775 In the main body of the matrix use the symbols to represent the degree of
connections between the feature and characteristics
6 Choose and define relationship symbols Most commonly used symbols are as
given below
Strong relationship=
Relationship =
Likely relationship=
Application
bull Matrix diagram can be used to solve problems by arranging data in such a way that
the relations between relevant factors are brought into sharp focus
bull There is no limit to the use of the tool
39
bull The most important application of matrix diagram is in clarifying relations between
individual features of customer requirements and individual product characteristics
Example 1
Matrix Diagram for Quality Functions and Responsibilities
40
41
6) Matrix Data Analysis Diagram1048577
Purpose
To present numerical data about two sets of factors in a matrix form and
analyze it to get numerical output
Can be applied in understanding the products and products characteristics
Procedure1048577
1 Decide the two factors whose relations are to be analyzed
2 Check the number of individual items in the two factors
3 Prepare a matrix to accommodate all the items of the two factors
4 Enter numerical data in the matrix
5 Give the diagram a suitable title
Example
42
43
44
7) Relationship diagram
This diagram clarifies the interrelations in a complex situation involving many
interrelated factors and serves to clarify the cause and effect relationships among
factors
Description
Relations diagram is defined as a technique used to solve problems that have complex
cause and effect relationships among a number of problems and factors that influence
them
Format
A special feature of relation diagram is its unrestricted Format However general
formats are as given below
1) Centrally converging relations diagram
The major item or problem to be solved is located in the center and the related factors
are arranged around the item or problem in such a way as to indicate close
relationships
2) Directionally intensive relations diagram
The major item or problem to be solved is located on one side of the diagram and the
various factors arranged in accordance with the flow of their major cause-and-effect
relationships on the other side
3) Relationship indication relations diagram
There are no restrictions on this format because the main point is to arrange the cause-
and-effect Relationships of the application items or factors so that they are expressed
in a straightforward manner in a Diagram
45
Procedure
1) Define the issueproblem in such a way that it is clearly understood and agreed on
by team members
2) Assemble the cross-functional team
3) Layout all the ideasissue cards that have been brought from other tools
4) Look for causeinfluence relationships between all ideas and draw relationship
arrows
a) Choose any of the ideas as a starting point and work through them in sequence
b)An outgoing arrow from an idea indicates that it is the stronger cause or influence
c) Draw only one way relationship arrows in the direction of the stronger cause or
Influence Make a decision on the stronger direction Do not draw two headed arrows
5) Review and revise the relationsrsquo diagram
6) Tally the number of outgoing and incoming arrows and select key items for further
planning
-record and clearly mark next to each issue the number of arrows going in and out of
it
-find the items with the highest number outgoing arrows and the items with the
highest number of incoming arrows
-a high number of outgoing arrows indicate that the item is a root cause and should be
tackle first
46
-a high number of incoming arrows indicate that the item is a key outcome and may
become a focus for planning either as a meaningful measure of overall success or as a
redefinition of the original issue under discussion
Example
47
48
Conclusions
Statististical QC is chiefly concerned in making sure that several procedures
and working arrangements are in place to provide for effective and efficient
statistical processes to minimize the risk of errors or weaknesses in
procedures or systems or in source material
Seven QC tools are most helpful in troubleshooting issues related to quality
All processes are affected by multiple factors and therefore statistical QC tools
can be applied to any process
The continuous use of these tools upgrades the personnel characteristics of the
people involved It enhances their ability to think generate ideas solve
problem and do proper planning
49
References asqorglearn-about-qualityseven-basic-quality-toolsoverviewhtml
httpsenwikipediaorgwikiSeven_Basic_Tools_of_Quality
wwwijergsorgfilesdocumentsAPPLICATION-45pd
httpssrcalionsciencecompdfQualityToolspdf
www3haorghkqehwiserdoc7bqtpdf
wwwmathmunca~variyathNew7QCToolspd
50
- 1 DEFINITION of Quality Control
- 3 Competitiveness
- 4 Customer Loyalty
- 5 Reputation
- 6 Compliance
- 7 Costs
- Benefits of Using Quality Control in Manufacturing
-
Scatter Diagram Example
The ZZ-400 manufacturing team suspects a relationship between product purity
(percent purity) and the amount of iron (measured in parts per million or ppm) Purity
and iron are plotted against each other as a scatter diagram as shown in the figure
below
There are 24 data points Median lines are drawn so that 12 points fall on each side for
both percent purity and ppm iron
To test for a relationship they calculate
A = points in upper left + points in lower right = 9 + 9 = 18
B = points in upper right + points in lower left = 3 + 3 = 6
Q = the smaller of A and B = the smaller of 18 and 6 = 6
N = A + B = 18 + 6 = 24
20
Then they look up the limit for N on the trend test table For N = 24 the limit is 6
Q is equal to the limit Therefore the pattern could have occurred from random
chance and no relationship is demonstrated
Scatter Diagram Example
Scatter Diagram Considerations
Here are some examples of situations in which might you use a scatter diagram
Variable A is the temperature of a reaction after 15 minutes Variable B measures the
colour of the product You suspect higher temperature makes the product darker Plot
temperature and colour on a scatter diagram
Variable A is the number of employees trained on new software and variable B is the
number of calls to the computer helps line You suspect that more training reduces the
number of calls Plot number of people trained versus number of calls
To test for autocorrelation of a measurement being monitored on a control chart plot
this pair of variables Variable A is the measurement at a given time Variable B is the
same measurement but at the previous time If the scatter diagram shows correlation
do another diagram where variable B is the measurement two times previously Keep
increasing the separation between the two times until the scatter diagram shows no
correlation
21
Even if the scatter diagram shows a relationship do not assume that one variable
caused the other Both may be influenced by a third variable
When the data are plotted the more the diagram resembles a straight line the stronger
the relationship
If a line is not clear statistics (N and Q) determine whether there is reasonable
certainty that a relationship exists If the statistics say that no relationship exists the
pattern could have occurred by random chance
If the scatter diagram shows no relationship between the variables consider whether
the data might be stratified
If the diagram shows no relationship consider whether the independent (x-axis)
variable has been varied widely Sometimes a relationship is not apparent because the
data donrsquot cover a wide enough range
Think creatively about how to use scatter diagrams to discover a root cause
Drawing a scatter diagram is the first step in looking for a relationship between
variables
22
7) Stratification
Stratification is a technique used in combination with other data analysis tools When
data from a variety of sources or categories have been lumped together the meaning
of the data can be impossible to see This technique separates the data so that patterns
can be seen
When to Use Stratification
Before collecting data
When data come from several sources or conditions such as shifts days of the
week suppliers or population groups
When data analysis may require separating different sources or conditions
Stratification Procedure
Before collecting data consider which information about the sources of the data
might have an effect on the results Set up the data collection so that you collect that
information as well
When plotting or graphing the collected data on a scatter diagram control chart
histogram or other analysis tool use different marks or colours to distinguish data
from various sources Data that are distinguished in this way are said to be
ldquostratifiedrdquo
Analyze the subsets of stratified data separately For example on a scatter diagram
where data are stratified into data from source 1 and data from source 2 draw
quadrants count points and determine the critical value only for the data from source
1 then only for the data from source 2
Stratification Example
23
The ZZndash400 manufacturing team drew a scatter diagram to test whether product
purity and iron contamination were related but the plot did not demonstrate a
relationship Then a team member realized that the data came from three different
reactors The team member redrew the diagram using a different symbol for each
reactorrsquos data
Now patterns can be seen The data from reactor 2 and reactor 3 are circled Even
without doing any calculations it is clear that for those two reactors purity decreases
as iron increases However the data from reactor 1 the solid dots that are not circled
do not show that relationship Something is different about reactor 1
Stratification Considerations
Here are examples of different sources that might require data to be stratified
Equipment
Shifts
Departments
24
Materials
Suppliers
Day of the week
Time of day
Products
Survey data usually benefit from stratification
Always consider before collecting data whether stratification might be needed during
analysis Plan to collect stratification information After the data are collected it might
be too late
On your graph or chart include a legend that identifies the marks or colours used
25
Now starting with new 7 quality control tool
Need of new quality control tool
Many customer requirements cannot always be adequately expressed by numerical
data alone Nevertheless even verbal statements can be expressions of facts because
it represents facts we ought to use Verbal data as well as numerical data in
controlling the managing quality It provides both quality control as well as
improvement during the manufacturing process
Benefits of new 7 quality control tool
Combine verbal with Numerical data
Looking for root cause
Clarify prioritize goals and schedule
Involve everyone into full cooperation and generate new ideas 1048577
The first new quality control tool is
1) Affinity Diagram
Application
An affinity diagram is used to organize into groupings large number of ideas opinions
or concerns about a Particular topic
Description
When a large number of ideas opinions or other concerns about a particular topic are
being collected this tool organizes the information into grouping~~based on the
natural relationships that exist among them The process is designed to stimulate
creativity and full participation It works best in groups of limited Size (a maximum
26
of eight members is recommended) in which members are accustomed to working
together This tool is often used to organize ideas generated by brainstorming
Procedure
State the topic to be studied in broad terms(details may prejudice the
response)
Record as many individual ideas opinions or concerns as possible on cards
(one per
card)
Mix the cards and spread them randomly on a large table
Group related cards together as follows
a)sort cards that seem to be related into groups and
b) limit number of grouping to ten without forcing single cards into groups
Locate or create a header card that captures the meaning of each group
Place this header card on top
Transfer the information from cards onto paper organized by groupings
Example For next generation digital camera we can organize the customer
Complains and requirements in an Affinity Diagram1048577
27
Affinity diagram
28
2) Tree diagram
Application
A tree diagram is used to show the interrelation between a topic and its component
elements
Description
A tree diagram systematically breaks down a topic into its component elements Ideas
generated by
Brainstorming and graphed or clustered with an affinity diagram can be converted
into a tree diagram
to show logical and sequential links This tool can be used in planning and problem
solving
Procedure
State the topic to be studied clearly
Define the major categories of the topic(brainstorm or use the header cards
from the affinity diagram)
Construct the diagram by placing the topic in a box on the left-hand side
Branch the major categories laterally to the right
For each major category define the component elements and sub-elements if
any
Laterally branch to the right the component elements and sub-elements for
each major category and
Review the diagram to ensure that there are no gaps in either sequence or
logic
29
30
3) Arrow diagram
Purpose To create a visual presentation of the steps of a process or tasks necessary to
complete a project with special emphasis on the time taken for these activities
Procedure
1 List all the tasks or activities needed to be accomplished before the process of the
project
2 Decide which steps are undertaken in series and which steps can be run in parallel
Arrange the
Activities in a proper sequence
3 Prepare lsquoEvent Nodesrsquo at the completion of steps and number them
4 Write the description of the step and decide the time required for completing each
step
5 Calculate the earliest time to reach an event node for the start of the process
7 Ager the time for all event nodes including the completion of the process or the
project is available one calculates the latest time by which an event node must be
reached
Application
The diagram is also useful in planning and scheduling steps in complicated processes
especially in planning and scheduling projects which involve a large number of
activities
Example
31
1 Identify the tasks Eg 123hellip15
2 Know the time each task needs
3 Determine which tasks can be run in parallel and in normal sequences
4 Draw the sequence diagram and find the critical path
5 Calculate the project duration
6 Calculate the earliest starting time (or the earliest finishing time of last task) and the
latest finishing time
of each task(the latest starting time for the following task)
7 Mark the time indication
32
33
4) Process Decision Program Chart (PDPC)
Def The process decision program chart (PDPC) method helps us select the best
processes to obtain optimum results by evaluating the progress of events and various
conceivable outcomes
Description
The process decision program chart (PDPC) method is used to define the solution
process when dealing with problems that have more than one possible outcome [t
anticipates the unexpected Outcomes at each stage and plans for it
PDPC has two following patterns
Pattern I ndash In this pattern process starts with initial condition lsquoArsquo and proceeds to the
desired final condition lsquoZrsquo in an organized manner
Pattern 11- In this pattern first the final conditionrsquosrsquo is set Then the process from lsquoZrsquo
to the initial point lsquoArsquo is developed with the inclusion of various alternatives from
many points of view
Procedure
Discuss the issues related to the project among a cross-functional team
Discuss which issues must be examined and identify those issues
Consider and note down all the anticipated results for the identified issues
Weigh the feasibility of each solution proposed and investigate alternate
solutions
Classify each issue according to its urgency number of operations required
likelihood of Occurrence and difficulty
Consider the anticipated results and alternative solutions related to issues that
must be addressed immediately and link the items with arrows to the desired
goal
34
Prioritize the different issues and consider them all together Information
related to one set of
Possibilities could influence another set Related items shall be linked with a
broken line
If the department that will handle a process involving several lines is
determined circle
the process and write the name of the department within
Set a target date for completion
Have regular meetings to check progress in terms of the original PDPC
35
36
37
38
5) Matrix diagram
Purpose1) Explore the existence and the extent of relations between individual items in 2 sets
of factors or features and characteristics and express them in a symbolic form that is
easy to understand
2) Mostly used to understand the relations between the customer expectations as
expressed by the customers and product characteristics as designed manufactured and
tested by the manufacturer
Procedures1 Determine 2 sets of factors for which the relations are needed to be established
2 Divide the features and characteristics into primary secondary and tertiary
characteristics
3 Place the features vertically on the leg side of the matrix and characteristics
horizontally on top of the matrix
4 Enter the importance of the features on the column ager that for the tertiary
features10485775 In the main body of the matrix use the symbols to represent the degree of
connections between the feature and characteristics
6 Choose and define relationship symbols Most commonly used symbols are as
given below
Strong relationship=
Relationship =
Likely relationship=
Application
bull Matrix diagram can be used to solve problems by arranging data in such a way that
the relations between relevant factors are brought into sharp focus
bull There is no limit to the use of the tool
39
bull The most important application of matrix diagram is in clarifying relations between
individual features of customer requirements and individual product characteristics
Example 1
Matrix Diagram for Quality Functions and Responsibilities
40
41
6) Matrix Data Analysis Diagram1048577
Purpose
To present numerical data about two sets of factors in a matrix form and
analyze it to get numerical output
Can be applied in understanding the products and products characteristics
Procedure1048577
1 Decide the two factors whose relations are to be analyzed
2 Check the number of individual items in the two factors
3 Prepare a matrix to accommodate all the items of the two factors
4 Enter numerical data in the matrix
5 Give the diagram a suitable title
Example
42
43
44
7) Relationship diagram
This diagram clarifies the interrelations in a complex situation involving many
interrelated factors and serves to clarify the cause and effect relationships among
factors
Description
Relations diagram is defined as a technique used to solve problems that have complex
cause and effect relationships among a number of problems and factors that influence
them
Format
A special feature of relation diagram is its unrestricted Format However general
formats are as given below
1) Centrally converging relations diagram
The major item or problem to be solved is located in the center and the related factors
are arranged around the item or problem in such a way as to indicate close
relationships
2) Directionally intensive relations diagram
The major item or problem to be solved is located on one side of the diagram and the
various factors arranged in accordance with the flow of their major cause-and-effect
relationships on the other side
3) Relationship indication relations diagram
There are no restrictions on this format because the main point is to arrange the cause-
and-effect Relationships of the application items or factors so that they are expressed
in a straightforward manner in a Diagram
45
Procedure
1) Define the issueproblem in such a way that it is clearly understood and agreed on
by team members
2) Assemble the cross-functional team
3) Layout all the ideasissue cards that have been brought from other tools
4) Look for causeinfluence relationships between all ideas and draw relationship
arrows
a) Choose any of the ideas as a starting point and work through them in sequence
b)An outgoing arrow from an idea indicates that it is the stronger cause or influence
c) Draw only one way relationship arrows in the direction of the stronger cause or
Influence Make a decision on the stronger direction Do not draw two headed arrows
5) Review and revise the relationsrsquo diagram
6) Tally the number of outgoing and incoming arrows and select key items for further
planning
-record and clearly mark next to each issue the number of arrows going in and out of
it
-find the items with the highest number outgoing arrows and the items with the
highest number of incoming arrows
-a high number of outgoing arrows indicate that the item is a root cause and should be
tackle first
46
-a high number of incoming arrows indicate that the item is a key outcome and may
become a focus for planning either as a meaningful measure of overall success or as a
redefinition of the original issue under discussion
Example
47
48
Conclusions
Statististical QC is chiefly concerned in making sure that several procedures
and working arrangements are in place to provide for effective and efficient
statistical processes to minimize the risk of errors or weaknesses in
procedures or systems or in source material
Seven QC tools are most helpful in troubleshooting issues related to quality
All processes are affected by multiple factors and therefore statistical QC tools
can be applied to any process
The continuous use of these tools upgrades the personnel characteristics of the
people involved It enhances their ability to think generate ideas solve
problem and do proper planning
49
References asqorglearn-about-qualityseven-basic-quality-toolsoverviewhtml
httpsenwikipediaorgwikiSeven_Basic_Tools_of_Quality
wwwijergsorgfilesdocumentsAPPLICATION-45pd
httpssrcalionsciencecompdfQualityToolspdf
www3haorghkqehwiserdoc7bqtpdf
wwwmathmunca~variyathNew7QCToolspd
50
- 1 DEFINITION of Quality Control
- 3 Competitiveness
- 4 Customer Loyalty
- 5 Reputation
- 6 Compliance
- 7 Costs
- Benefits of Using Quality Control in Manufacturing
-
Then they look up the limit for N on the trend test table For N = 24 the limit is 6
Q is equal to the limit Therefore the pattern could have occurred from random
chance and no relationship is demonstrated
Scatter Diagram Example
Scatter Diagram Considerations
Here are some examples of situations in which might you use a scatter diagram
Variable A is the temperature of a reaction after 15 minutes Variable B measures the
colour of the product You suspect higher temperature makes the product darker Plot
temperature and colour on a scatter diagram
Variable A is the number of employees trained on new software and variable B is the
number of calls to the computer helps line You suspect that more training reduces the
number of calls Plot number of people trained versus number of calls
To test for autocorrelation of a measurement being monitored on a control chart plot
this pair of variables Variable A is the measurement at a given time Variable B is the
same measurement but at the previous time If the scatter diagram shows correlation
do another diagram where variable B is the measurement two times previously Keep
increasing the separation between the two times until the scatter diagram shows no
correlation
21
Even if the scatter diagram shows a relationship do not assume that one variable
caused the other Both may be influenced by a third variable
When the data are plotted the more the diagram resembles a straight line the stronger
the relationship
If a line is not clear statistics (N and Q) determine whether there is reasonable
certainty that a relationship exists If the statistics say that no relationship exists the
pattern could have occurred by random chance
If the scatter diagram shows no relationship between the variables consider whether
the data might be stratified
If the diagram shows no relationship consider whether the independent (x-axis)
variable has been varied widely Sometimes a relationship is not apparent because the
data donrsquot cover a wide enough range
Think creatively about how to use scatter diagrams to discover a root cause
Drawing a scatter diagram is the first step in looking for a relationship between
variables
22
7) Stratification
Stratification is a technique used in combination with other data analysis tools When
data from a variety of sources or categories have been lumped together the meaning
of the data can be impossible to see This technique separates the data so that patterns
can be seen
When to Use Stratification
Before collecting data
When data come from several sources or conditions such as shifts days of the
week suppliers or population groups
When data analysis may require separating different sources or conditions
Stratification Procedure
Before collecting data consider which information about the sources of the data
might have an effect on the results Set up the data collection so that you collect that
information as well
When plotting or graphing the collected data on a scatter diagram control chart
histogram or other analysis tool use different marks or colours to distinguish data
from various sources Data that are distinguished in this way are said to be
ldquostratifiedrdquo
Analyze the subsets of stratified data separately For example on a scatter diagram
where data are stratified into data from source 1 and data from source 2 draw
quadrants count points and determine the critical value only for the data from source
1 then only for the data from source 2
Stratification Example
23
The ZZndash400 manufacturing team drew a scatter diagram to test whether product
purity and iron contamination were related but the plot did not demonstrate a
relationship Then a team member realized that the data came from three different
reactors The team member redrew the diagram using a different symbol for each
reactorrsquos data
Now patterns can be seen The data from reactor 2 and reactor 3 are circled Even
without doing any calculations it is clear that for those two reactors purity decreases
as iron increases However the data from reactor 1 the solid dots that are not circled
do not show that relationship Something is different about reactor 1
Stratification Considerations
Here are examples of different sources that might require data to be stratified
Equipment
Shifts
Departments
24
Materials
Suppliers
Day of the week
Time of day
Products
Survey data usually benefit from stratification
Always consider before collecting data whether stratification might be needed during
analysis Plan to collect stratification information After the data are collected it might
be too late
On your graph or chart include a legend that identifies the marks or colours used
25
Now starting with new 7 quality control tool
Need of new quality control tool
Many customer requirements cannot always be adequately expressed by numerical
data alone Nevertheless even verbal statements can be expressions of facts because
it represents facts we ought to use Verbal data as well as numerical data in
controlling the managing quality It provides both quality control as well as
improvement during the manufacturing process
Benefits of new 7 quality control tool
Combine verbal with Numerical data
Looking for root cause
Clarify prioritize goals and schedule
Involve everyone into full cooperation and generate new ideas 1048577
The first new quality control tool is
1) Affinity Diagram
Application
An affinity diagram is used to organize into groupings large number of ideas opinions
or concerns about a Particular topic
Description
When a large number of ideas opinions or other concerns about a particular topic are
being collected this tool organizes the information into grouping~~based on the
natural relationships that exist among them The process is designed to stimulate
creativity and full participation It works best in groups of limited Size (a maximum
26
of eight members is recommended) in which members are accustomed to working
together This tool is often used to organize ideas generated by brainstorming
Procedure
State the topic to be studied in broad terms(details may prejudice the
response)
Record as many individual ideas opinions or concerns as possible on cards
(one per
card)
Mix the cards and spread them randomly on a large table
Group related cards together as follows
a)sort cards that seem to be related into groups and
b) limit number of grouping to ten without forcing single cards into groups
Locate or create a header card that captures the meaning of each group
Place this header card on top
Transfer the information from cards onto paper organized by groupings
Example For next generation digital camera we can organize the customer
Complains and requirements in an Affinity Diagram1048577
27
Affinity diagram
28
2) Tree diagram
Application
A tree diagram is used to show the interrelation between a topic and its component
elements
Description
A tree diagram systematically breaks down a topic into its component elements Ideas
generated by
Brainstorming and graphed or clustered with an affinity diagram can be converted
into a tree diagram
to show logical and sequential links This tool can be used in planning and problem
solving
Procedure
State the topic to be studied clearly
Define the major categories of the topic(brainstorm or use the header cards
from the affinity diagram)
Construct the diagram by placing the topic in a box on the left-hand side
Branch the major categories laterally to the right
For each major category define the component elements and sub-elements if
any
Laterally branch to the right the component elements and sub-elements for
each major category and
Review the diagram to ensure that there are no gaps in either sequence or
logic
29
30
3) Arrow diagram
Purpose To create a visual presentation of the steps of a process or tasks necessary to
complete a project with special emphasis on the time taken for these activities
Procedure
1 List all the tasks or activities needed to be accomplished before the process of the
project
2 Decide which steps are undertaken in series and which steps can be run in parallel
Arrange the
Activities in a proper sequence
3 Prepare lsquoEvent Nodesrsquo at the completion of steps and number them
4 Write the description of the step and decide the time required for completing each
step
5 Calculate the earliest time to reach an event node for the start of the process
7 Ager the time for all event nodes including the completion of the process or the
project is available one calculates the latest time by which an event node must be
reached
Application
The diagram is also useful in planning and scheduling steps in complicated processes
especially in planning and scheduling projects which involve a large number of
activities
Example
31
1 Identify the tasks Eg 123hellip15
2 Know the time each task needs
3 Determine which tasks can be run in parallel and in normal sequences
4 Draw the sequence diagram and find the critical path
5 Calculate the project duration
6 Calculate the earliest starting time (or the earliest finishing time of last task) and the
latest finishing time
of each task(the latest starting time for the following task)
7 Mark the time indication
32
33
4) Process Decision Program Chart (PDPC)
Def The process decision program chart (PDPC) method helps us select the best
processes to obtain optimum results by evaluating the progress of events and various
conceivable outcomes
Description
The process decision program chart (PDPC) method is used to define the solution
process when dealing with problems that have more than one possible outcome [t
anticipates the unexpected Outcomes at each stage and plans for it
PDPC has two following patterns
Pattern I ndash In this pattern process starts with initial condition lsquoArsquo and proceeds to the
desired final condition lsquoZrsquo in an organized manner
Pattern 11- In this pattern first the final conditionrsquosrsquo is set Then the process from lsquoZrsquo
to the initial point lsquoArsquo is developed with the inclusion of various alternatives from
many points of view
Procedure
Discuss the issues related to the project among a cross-functional team
Discuss which issues must be examined and identify those issues
Consider and note down all the anticipated results for the identified issues
Weigh the feasibility of each solution proposed and investigate alternate
solutions
Classify each issue according to its urgency number of operations required
likelihood of Occurrence and difficulty
Consider the anticipated results and alternative solutions related to issues that
must be addressed immediately and link the items with arrows to the desired
goal
34
Prioritize the different issues and consider them all together Information
related to one set of
Possibilities could influence another set Related items shall be linked with a
broken line
If the department that will handle a process involving several lines is
determined circle
the process and write the name of the department within
Set a target date for completion
Have regular meetings to check progress in terms of the original PDPC
35
36
37
38
5) Matrix diagram
Purpose1) Explore the existence and the extent of relations between individual items in 2 sets
of factors or features and characteristics and express them in a symbolic form that is
easy to understand
2) Mostly used to understand the relations between the customer expectations as
expressed by the customers and product characteristics as designed manufactured and
tested by the manufacturer
Procedures1 Determine 2 sets of factors for which the relations are needed to be established
2 Divide the features and characteristics into primary secondary and tertiary
characteristics
3 Place the features vertically on the leg side of the matrix and characteristics
horizontally on top of the matrix
4 Enter the importance of the features on the column ager that for the tertiary
features10485775 In the main body of the matrix use the symbols to represent the degree of
connections between the feature and characteristics
6 Choose and define relationship symbols Most commonly used symbols are as
given below
Strong relationship=
Relationship =
Likely relationship=
Application
bull Matrix diagram can be used to solve problems by arranging data in such a way that
the relations between relevant factors are brought into sharp focus
bull There is no limit to the use of the tool
39
bull The most important application of matrix diagram is in clarifying relations between
individual features of customer requirements and individual product characteristics
Example 1
Matrix Diagram for Quality Functions and Responsibilities
40
41
6) Matrix Data Analysis Diagram1048577
Purpose
To present numerical data about two sets of factors in a matrix form and
analyze it to get numerical output
Can be applied in understanding the products and products characteristics
Procedure1048577
1 Decide the two factors whose relations are to be analyzed
2 Check the number of individual items in the two factors
3 Prepare a matrix to accommodate all the items of the two factors
4 Enter numerical data in the matrix
5 Give the diagram a suitable title
Example
42
43
44
7) Relationship diagram
This diagram clarifies the interrelations in a complex situation involving many
interrelated factors and serves to clarify the cause and effect relationships among
factors
Description
Relations diagram is defined as a technique used to solve problems that have complex
cause and effect relationships among a number of problems and factors that influence
them
Format
A special feature of relation diagram is its unrestricted Format However general
formats are as given below
1) Centrally converging relations diagram
The major item or problem to be solved is located in the center and the related factors
are arranged around the item or problem in such a way as to indicate close
relationships
2) Directionally intensive relations diagram
The major item or problem to be solved is located on one side of the diagram and the
various factors arranged in accordance with the flow of their major cause-and-effect
relationships on the other side
3) Relationship indication relations diagram
There are no restrictions on this format because the main point is to arrange the cause-
and-effect Relationships of the application items or factors so that they are expressed
in a straightforward manner in a Diagram
45
Procedure
1) Define the issueproblem in such a way that it is clearly understood and agreed on
by team members
2) Assemble the cross-functional team
3) Layout all the ideasissue cards that have been brought from other tools
4) Look for causeinfluence relationships between all ideas and draw relationship
arrows
a) Choose any of the ideas as a starting point and work through them in sequence
b)An outgoing arrow from an idea indicates that it is the stronger cause or influence
c) Draw only one way relationship arrows in the direction of the stronger cause or
Influence Make a decision on the stronger direction Do not draw two headed arrows
5) Review and revise the relationsrsquo diagram
6) Tally the number of outgoing and incoming arrows and select key items for further
planning
-record and clearly mark next to each issue the number of arrows going in and out of
it
-find the items with the highest number outgoing arrows and the items with the
highest number of incoming arrows
-a high number of outgoing arrows indicate that the item is a root cause and should be
tackle first
46
-a high number of incoming arrows indicate that the item is a key outcome and may
become a focus for planning either as a meaningful measure of overall success or as a
redefinition of the original issue under discussion
Example
47
48
Conclusions
Statististical QC is chiefly concerned in making sure that several procedures
and working arrangements are in place to provide for effective and efficient
statistical processes to minimize the risk of errors or weaknesses in
procedures or systems or in source material
Seven QC tools are most helpful in troubleshooting issues related to quality
All processes are affected by multiple factors and therefore statistical QC tools
can be applied to any process
The continuous use of these tools upgrades the personnel characteristics of the
people involved It enhances their ability to think generate ideas solve
problem and do proper planning
49
References asqorglearn-about-qualityseven-basic-quality-toolsoverviewhtml
httpsenwikipediaorgwikiSeven_Basic_Tools_of_Quality
wwwijergsorgfilesdocumentsAPPLICATION-45pd
httpssrcalionsciencecompdfQualityToolspdf
www3haorghkqehwiserdoc7bqtpdf
wwwmathmunca~variyathNew7QCToolspd
50
- 1 DEFINITION of Quality Control
- 3 Competitiveness
- 4 Customer Loyalty
- 5 Reputation
- 6 Compliance
- 7 Costs
- Benefits of Using Quality Control in Manufacturing
-
Even if the scatter diagram shows a relationship do not assume that one variable
caused the other Both may be influenced by a third variable
When the data are plotted the more the diagram resembles a straight line the stronger
the relationship
If a line is not clear statistics (N and Q) determine whether there is reasonable
certainty that a relationship exists If the statistics say that no relationship exists the
pattern could have occurred by random chance
If the scatter diagram shows no relationship between the variables consider whether
the data might be stratified
If the diagram shows no relationship consider whether the independent (x-axis)
variable has been varied widely Sometimes a relationship is not apparent because the
data donrsquot cover a wide enough range
Think creatively about how to use scatter diagrams to discover a root cause
Drawing a scatter diagram is the first step in looking for a relationship between
variables
22
7) Stratification
Stratification is a technique used in combination with other data analysis tools When
data from a variety of sources or categories have been lumped together the meaning
of the data can be impossible to see This technique separates the data so that patterns
can be seen
When to Use Stratification
Before collecting data
When data come from several sources or conditions such as shifts days of the
week suppliers or population groups
When data analysis may require separating different sources or conditions
Stratification Procedure
Before collecting data consider which information about the sources of the data
might have an effect on the results Set up the data collection so that you collect that
information as well
When plotting or graphing the collected data on a scatter diagram control chart
histogram or other analysis tool use different marks or colours to distinguish data
from various sources Data that are distinguished in this way are said to be
ldquostratifiedrdquo
Analyze the subsets of stratified data separately For example on a scatter diagram
where data are stratified into data from source 1 and data from source 2 draw
quadrants count points and determine the critical value only for the data from source
1 then only for the data from source 2
Stratification Example
23
The ZZndash400 manufacturing team drew a scatter diagram to test whether product
purity and iron contamination were related but the plot did not demonstrate a
relationship Then a team member realized that the data came from three different
reactors The team member redrew the diagram using a different symbol for each
reactorrsquos data
Now patterns can be seen The data from reactor 2 and reactor 3 are circled Even
without doing any calculations it is clear that for those two reactors purity decreases
as iron increases However the data from reactor 1 the solid dots that are not circled
do not show that relationship Something is different about reactor 1
Stratification Considerations
Here are examples of different sources that might require data to be stratified
Equipment
Shifts
Departments
24
Materials
Suppliers
Day of the week
Time of day
Products
Survey data usually benefit from stratification
Always consider before collecting data whether stratification might be needed during
analysis Plan to collect stratification information After the data are collected it might
be too late
On your graph or chart include a legend that identifies the marks or colours used
25
Now starting with new 7 quality control tool
Need of new quality control tool
Many customer requirements cannot always be adequately expressed by numerical
data alone Nevertheless even verbal statements can be expressions of facts because
it represents facts we ought to use Verbal data as well as numerical data in
controlling the managing quality It provides both quality control as well as
improvement during the manufacturing process
Benefits of new 7 quality control tool
Combine verbal with Numerical data
Looking for root cause
Clarify prioritize goals and schedule
Involve everyone into full cooperation and generate new ideas 1048577
The first new quality control tool is
1) Affinity Diagram
Application
An affinity diagram is used to organize into groupings large number of ideas opinions
or concerns about a Particular topic
Description
When a large number of ideas opinions or other concerns about a particular topic are
being collected this tool organizes the information into grouping~~based on the
natural relationships that exist among them The process is designed to stimulate
creativity and full participation It works best in groups of limited Size (a maximum
26
of eight members is recommended) in which members are accustomed to working
together This tool is often used to organize ideas generated by brainstorming
Procedure
State the topic to be studied in broad terms(details may prejudice the
response)
Record as many individual ideas opinions or concerns as possible on cards
(one per
card)
Mix the cards and spread them randomly on a large table
Group related cards together as follows
a)sort cards that seem to be related into groups and
b) limit number of grouping to ten without forcing single cards into groups
Locate or create a header card that captures the meaning of each group
Place this header card on top
Transfer the information from cards onto paper organized by groupings
Example For next generation digital camera we can organize the customer
Complains and requirements in an Affinity Diagram1048577
27
Affinity diagram
28
2) Tree diagram
Application
A tree diagram is used to show the interrelation between a topic and its component
elements
Description
A tree diagram systematically breaks down a topic into its component elements Ideas
generated by
Brainstorming and graphed or clustered with an affinity diagram can be converted
into a tree diagram
to show logical and sequential links This tool can be used in planning and problem
solving
Procedure
State the topic to be studied clearly
Define the major categories of the topic(brainstorm or use the header cards
from the affinity diagram)
Construct the diagram by placing the topic in a box on the left-hand side
Branch the major categories laterally to the right
For each major category define the component elements and sub-elements if
any
Laterally branch to the right the component elements and sub-elements for
each major category and
Review the diagram to ensure that there are no gaps in either sequence or
logic
29
30
3) Arrow diagram
Purpose To create a visual presentation of the steps of a process or tasks necessary to
complete a project with special emphasis on the time taken for these activities
Procedure
1 List all the tasks or activities needed to be accomplished before the process of the
project
2 Decide which steps are undertaken in series and which steps can be run in parallel
Arrange the
Activities in a proper sequence
3 Prepare lsquoEvent Nodesrsquo at the completion of steps and number them
4 Write the description of the step and decide the time required for completing each
step
5 Calculate the earliest time to reach an event node for the start of the process
7 Ager the time for all event nodes including the completion of the process or the
project is available one calculates the latest time by which an event node must be
reached
Application
The diagram is also useful in planning and scheduling steps in complicated processes
especially in planning and scheduling projects which involve a large number of
activities
Example
31
1 Identify the tasks Eg 123hellip15
2 Know the time each task needs
3 Determine which tasks can be run in parallel and in normal sequences
4 Draw the sequence diagram and find the critical path
5 Calculate the project duration
6 Calculate the earliest starting time (or the earliest finishing time of last task) and the
latest finishing time
of each task(the latest starting time for the following task)
7 Mark the time indication
32
33
4) Process Decision Program Chart (PDPC)
Def The process decision program chart (PDPC) method helps us select the best
processes to obtain optimum results by evaluating the progress of events and various
conceivable outcomes
Description
The process decision program chart (PDPC) method is used to define the solution
process when dealing with problems that have more than one possible outcome [t
anticipates the unexpected Outcomes at each stage and plans for it
PDPC has two following patterns
Pattern I ndash In this pattern process starts with initial condition lsquoArsquo and proceeds to the
desired final condition lsquoZrsquo in an organized manner
Pattern 11- In this pattern first the final conditionrsquosrsquo is set Then the process from lsquoZrsquo
to the initial point lsquoArsquo is developed with the inclusion of various alternatives from
many points of view
Procedure
Discuss the issues related to the project among a cross-functional team
Discuss which issues must be examined and identify those issues
Consider and note down all the anticipated results for the identified issues
Weigh the feasibility of each solution proposed and investigate alternate
solutions
Classify each issue according to its urgency number of operations required
likelihood of Occurrence and difficulty
Consider the anticipated results and alternative solutions related to issues that
must be addressed immediately and link the items with arrows to the desired
goal
34
Prioritize the different issues and consider them all together Information
related to one set of
Possibilities could influence another set Related items shall be linked with a
broken line
If the department that will handle a process involving several lines is
determined circle
the process and write the name of the department within
Set a target date for completion
Have regular meetings to check progress in terms of the original PDPC
35
36
37
38
5) Matrix diagram
Purpose1) Explore the existence and the extent of relations between individual items in 2 sets
of factors or features and characteristics and express them in a symbolic form that is
easy to understand
2) Mostly used to understand the relations between the customer expectations as
expressed by the customers and product characteristics as designed manufactured and
tested by the manufacturer
Procedures1 Determine 2 sets of factors for which the relations are needed to be established
2 Divide the features and characteristics into primary secondary and tertiary
characteristics
3 Place the features vertically on the leg side of the matrix and characteristics
horizontally on top of the matrix
4 Enter the importance of the features on the column ager that for the tertiary
features10485775 In the main body of the matrix use the symbols to represent the degree of
connections between the feature and characteristics
6 Choose and define relationship symbols Most commonly used symbols are as
given below
Strong relationship=
Relationship =
Likely relationship=
Application
bull Matrix diagram can be used to solve problems by arranging data in such a way that
the relations between relevant factors are brought into sharp focus
bull There is no limit to the use of the tool
39
bull The most important application of matrix diagram is in clarifying relations between
individual features of customer requirements and individual product characteristics
Example 1
Matrix Diagram for Quality Functions and Responsibilities
40
41
6) Matrix Data Analysis Diagram1048577
Purpose
To present numerical data about two sets of factors in a matrix form and
analyze it to get numerical output
Can be applied in understanding the products and products characteristics
Procedure1048577
1 Decide the two factors whose relations are to be analyzed
2 Check the number of individual items in the two factors
3 Prepare a matrix to accommodate all the items of the two factors
4 Enter numerical data in the matrix
5 Give the diagram a suitable title
Example
42
43
44
7) Relationship diagram
This diagram clarifies the interrelations in a complex situation involving many
interrelated factors and serves to clarify the cause and effect relationships among
factors
Description
Relations diagram is defined as a technique used to solve problems that have complex
cause and effect relationships among a number of problems and factors that influence
them
Format
A special feature of relation diagram is its unrestricted Format However general
formats are as given below
1) Centrally converging relations diagram
The major item or problem to be solved is located in the center and the related factors
are arranged around the item or problem in such a way as to indicate close
relationships
2) Directionally intensive relations diagram
The major item or problem to be solved is located on one side of the diagram and the
various factors arranged in accordance with the flow of their major cause-and-effect
relationships on the other side
3) Relationship indication relations diagram
There are no restrictions on this format because the main point is to arrange the cause-
and-effect Relationships of the application items or factors so that they are expressed
in a straightforward manner in a Diagram
45
Procedure
1) Define the issueproblem in such a way that it is clearly understood and agreed on
by team members
2) Assemble the cross-functional team
3) Layout all the ideasissue cards that have been brought from other tools
4) Look for causeinfluence relationships between all ideas and draw relationship
arrows
a) Choose any of the ideas as a starting point and work through them in sequence
b)An outgoing arrow from an idea indicates that it is the stronger cause or influence
c) Draw only one way relationship arrows in the direction of the stronger cause or
Influence Make a decision on the stronger direction Do not draw two headed arrows
5) Review and revise the relationsrsquo diagram
6) Tally the number of outgoing and incoming arrows and select key items for further
planning
-record and clearly mark next to each issue the number of arrows going in and out of
it
-find the items with the highest number outgoing arrows and the items with the
highest number of incoming arrows
-a high number of outgoing arrows indicate that the item is a root cause and should be
tackle first
46
-a high number of incoming arrows indicate that the item is a key outcome and may
become a focus for planning either as a meaningful measure of overall success or as a
redefinition of the original issue under discussion
Example
47
48
Conclusions
Statististical QC is chiefly concerned in making sure that several procedures
and working arrangements are in place to provide for effective and efficient
statistical processes to minimize the risk of errors or weaknesses in
procedures or systems or in source material
Seven QC tools are most helpful in troubleshooting issues related to quality
All processes are affected by multiple factors and therefore statistical QC tools
can be applied to any process
The continuous use of these tools upgrades the personnel characteristics of the
people involved It enhances their ability to think generate ideas solve
problem and do proper planning
49
References asqorglearn-about-qualityseven-basic-quality-toolsoverviewhtml
httpsenwikipediaorgwikiSeven_Basic_Tools_of_Quality
wwwijergsorgfilesdocumentsAPPLICATION-45pd
httpssrcalionsciencecompdfQualityToolspdf
www3haorghkqehwiserdoc7bqtpdf
wwwmathmunca~variyathNew7QCToolspd
50
- 1 DEFINITION of Quality Control
- 3 Competitiveness
- 4 Customer Loyalty
- 5 Reputation
- 6 Compliance
- 7 Costs
- Benefits of Using Quality Control in Manufacturing
-
7) Stratification
Stratification is a technique used in combination with other data analysis tools When
data from a variety of sources or categories have been lumped together the meaning
of the data can be impossible to see This technique separates the data so that patterns
can be seen
When to Use Stratification
Before collecting data
When data come from several sources or conditions such as shifts days of the
week suppliers or population groups
When data analysis may require separating different sources or conditions
Stratification Procedure
Before collecting data consider which information about the sources of the data
might have an effect on the results Set up the data collection so that you collect that
information as well
When plotting or graphing the collected data on a scatter diagram control chart
histogram or other analysis tool use different marks or colours to distinguish data
from various sources Data that are distinguished in this way are said to be
ldquostratifiedrdquo
Analyze the subsets of stratified data separately For example on a scatter diagram
where data are stratified into data from source 1 and data from source 2 draw
quadrants count points and determine the critical value only for the data from source
1 then only for the data from source 2
Stratification Example
23
The ZZndash400 manufacturing team drew a scatter diagram to test whether product
purity and iron contamination were related but the plot did not demonstrate a
relationship Then a team member realized that the data came from three different
reactors The team member redrew the diagram using a different symbol for each
reactorrsquos data
Now patterns can be seen The data from reactor 2 and reactor 3 are circled Even
without doing any calculations it is clear that for those two reactors purity decreases
as iron increases However the data from reactor 1 the solid dots that are not circled
do not show that relationship Something is different about reactor 1
Stratification Considerations
Here are examples of different sources that might require data to be stratified
Equipment
Shifts
Departments
24
Materials
Suppliers
Day of the week
Time of day
Products
Survey data usually benefit from stratification
Always consider before collecting data whether stratification might be needed during
analysis Plan to collect stratification information After the data are collected it might
be too late
On your graph or chart include a legend that identifies the marks or colours used
25
Now starting with new 7 quality control tool
Need of new quality control tool
Many customer requirements cannot always be adequately expressed by numerical
data alone Nevertheless even verbal statements can be expressions of facts because
it represents facts we ought to use Verbal data as well as numerical data in
controlling the managing quality It provides both quality control as well as
improvement during the manufacturing process
Benefits of new 7 quality control tool
Combine verbal with Numerical data
Looking for root cause
Clarify prioritize goals and schedule
Involve everyone into full cooperation and generate new ideas 1048577
The first new quality control tool is
1) Affinity Diagram
Application
An affinity diagram is used to organize into groupings large number of ideas opinions
or concerns about a Particular topic
Description
When a large number of ideas opinions or other concerns about a particular topic are
being collected this tool organizes the information into grouping~~based on the
natural relationships that exist among them The process is designed to stimulate
creativity and full participation It works best in groups of limited Size (a maximum
26
of eight members is recommended) in which members are accustomed to working
together This tool is often used to organize ideas generated by brainstorming
Procedure
State the topic to be studied in broad terms(details may prejudice the
response)
Record as many individual ideas opinions or concerns as possible on cards
(one per
card)
Mix the cards and spread them randomly on a large table
Group related cards together as follows
a)sort cards that seem to be related into groups and
b) limit number of grouping to ten without forcing single cards into groups
Locate or create a header card that captures the meaning of each group
Place this header card on top
Transfer the information from cards onto paper organized by groupings
Example For next generation digital camera we can organize the customer
Complains and requirements in an Affinity Diagram1048577
27
Affinity diagram
28
2) Tree diagram
Application
A tree diagram is used to show the interrelation between a topic and its component
elements
Description
A tree diagram systematically breaks down a topic into its component elements Ideas
generated by
Brainstorming and graphed or clustered with an affinity diagram can be converted
into a tree diagram
to show logical and sequential links This tool can be used in planning and problem
solving
Procedure
State the topic to be studied clearly
Define the major categories of the topic(brainstorm or use the header cards
from the affinity diagram)
Construct the diagram by placing the topic in a box on the left-hand side
Branch the major categories laterally to the right
For each major category define the component elements and sub-elements if
any
Laterally branch to the right the component elements and sub-elements for
each major category and
Review the diagram to ensure that there are no gaps in either sequence or
logic
29
30
3) Arrow diagram
Purpose To create a visual presentation of the steps of a process or tasks necessary to
complete a project with special emphasis on the time taken for these activities
Procedure
1 List all the tasks or activities needed to be accomplished before the process of the
project
2 Decide which steps are undertaken in series and which steps can be run in parallel
Arrange the
Activities in a proper sequence
3 Prepare lsquoEvent Nodesrsquo at the completion of steps and number them
4 Write the description of the step and decide the time required for completing each
step
5 Calculate the earliest time to reach an event node for the start of the process
7 Ager the time for all event nodes including the completion of the process or the
project is available one calculates the latest time by which an event node must be
reached
Application
The diagram is also useful in planning and scheduling steps in complicated processes
especially in planning and scheduling projects which involve a large number of
activities
Example
31
1 Identify the tasks Eg 123hellip15
2 Know the time each task needs
3 Determine which tasks can be run in parallel and in normal sequences
4 Draw the sequence diagram and find the critical path
5 Calculate the project duration
6 Calculate the earliest starting time (or the earliest finishing time of last task) and the
latest finishing time
of each task(the latest starting time for the following task)
7 Mark the time indication
32
33
4) Process Decision Program Chart (PDPC)
Def The process decision program chart (PDPC) method helps us select the best
processes to obtain optimum results by evaluating the progress of events and various
conceivable outcomes
Description
The process decision program chart (PDPC) method is used to define the solution
process when dealing with problems that have more than one possible outcome [t
anticipates the unexpected Outcomes at each stage and plans for it
PDPC has two following patterns
Pattern I ndash In this pattern process starts with initial condition lsquoArsquo and proceeds to the
desired final condition lsquoZrsquo in an organized manner
Pattern 11- In this pattern first the final conditionrsquosrsquo is set Then the process from lsquoZrsquo
to the initial point lsquoArsquo is developed with the inclusion of various alternatives from
many points of view
Procedure
Discuss the issues related to the project among a cross-functional team
Discuss which issues must be examined and identify those issues
Consider and note down all the anticipated results for the identified issues
Weigh the feasibility of each solution proposed and investigate alternate
solutions
Classify each issue according to its urgency number of operations required
likelihood of Occurrence and difficulty
Consider the anticipated results and alternative solutions related to issues that
must be addressed immediately and link the items with arrows to the desired
goal
34
Prioritize the different issues and consider them all together Information
related to one set of
Possibilities could influence another set Related items shall be linked with a
broken line
If the department that will handle a process involving several lines is
determined circle
the process and write the name of the department within
Set a target date for completion
Have regular meetings to check progress in terms of the original PDPC
35
36
37
38
5) Matrix diagram
Purpose1) Explore the existence and the extent of relations between individual items in 2 sets
of factors or features and characteristics and express them in a symbolic form that is
easy to understand
2) Mostly used to understand the relations between the customer expectations as
expressed by the customers and product characteristics as designed manufactured and
tested by the manufacturer
Procedures1 Determine 2 sets of factors for which the relations are needed to be established
2 Divide the features and characteristics into primary secondary and tertiary
characteristics
3 Place the features vertically on the leg side of the matrix and characteristics
horizontally on top of the matrix
4 Enter the importance of the features on the column ager that for the tertiary
features10485775 In the main body of the matrix use the symbols to represent the degree of
connections between the feature and characteristics
6 Choose and define relationship symbols Most commonly used symbols are as
given below
Strong relationship=
Relationship =
Likely relationship=
Application
bull Matrix diagram can be used to solve problems by arranging data in such a way that
the relations between relevant factors are brought into sharp focus
bull There is no limit to the use of the tool
39
bull The most important application of matrix diagram is in clarifying relations between
individual features of customer requirements and individual product characteristics
Example 1
Matrix Diagram for Quality Functions and Responsibilities
40
41
6) Matrix Data Analysis Diagram1048577
Purpose
To present numerical data about two sets of factors in a matrix form and
analyze it to get numerical output
Can be applied in understanding the products and products characteristics
Procedure1048577
1 Decide the two factors whose relations are to be analyzed
2 Check the number of individual items in the two factors
3 Prepare a matrix to accommodate all the items of the two factors
4 Enter numerical data in the matrix
5 Give the diagram a suitable title
Example
42
43
44
7) Relationship diagram
This diagram clarifies the interrelations in a complex situation involving many
interrelated factors and serves to clarify the cause and effect relationships among
factors
Description
Relations diagram is defined as a technique used to solve problems that have complex
cause and effect relationships among a number of problems and factors that influence
them
Format
A special feature of relation diagram is its unrestricted Format However general
formats are as given below
1) Centrally converging relations diagram
The major item or problem to be solved is located in the center and the related factors
are arranged around the item or problem in such a way as to indicate close
relationships
2) Directionally intensive relations diagram
The major item or problem to be solved is located on one side of the diagram and the
various factors arranged in accordance with the flow of their major cause-and-effect
relationships on the other side
3) Relationship indication relations diagram
There are no restrictions on this format because the main point is to arrange the cause-
and-effect Relationships of the application items or factors so that they are expressed
in a straightforward manner in a Diagram
45
Procedure
1) Define the issueproblem in such a way that it is clearly understood and agreed on
by team members
2) Assemble the cross-functional team
3) Layout all the ideasissue cards that have been brought from other tools
4) Look for causeinfluence relationships between all ideas and draw relationship
arrows
a) Choose any of the ideas as a starting point and work through them in sequence
b)An outgoing arrow from an idea indicates that it is the stronger cause or influence
c) Draw only one way relationship arrows in the direction of the stronger cause or
Influence Make a decision on the stronger direction Do not draw two headed arrows
5) Review and revise the relationsrsquo diagram
6) Tally the number of outgoing and incoming arrows and select key items for further
planning
-record and clearly mark next to each issue the number of arrows going in and out of
it
-find the items with the highest number outgoing arrows and the items with the
highest number of incoming arrows
-a high number of outgoing arrows indicate that the item is a root cause and should be
tackle first
46
-a high number of incoming arrows indicate that the item is a key outcome and may
become a focus for planning either as a meaningful measure of overall success or as a
redefinition of the original issue under discussion
Example
47
48
Conclusions
Statististical QC is chiefly concerned in making sure that several procedures
and working arrangements are in place to provide for effective and efficient
statistical processes to minimize the risk of errors or weaknesses in
procedures or systems or in source material
Seven QC tools are most helpful in troubleshooting issues related to quality
All processes are affected by multiple factors and therefore statistical QC tools
can be applied to any process
The continuous use of these tools upgrades the personnel characteristics of the
people involved It enhances their ability to think generate ideas solve
problem and do proper planning
49
References asqorglearn-about-qualityseven-basic-quality-toolsoverviewhtml
httpsenwikipediaorgwikiSeven_Basic_Tools_of_Quality
wwwijergsorgfilesdocumentsAPPLICATION-45pd
httpssrcalionsciencecompdfQualityToolspdf
www3haorghkqehwiserdoc7bqtpdf
wwwmathmunca~variyathNew7QCToolspd
50
- 1 DEFINITION of Quality Control
- 3 Competitiveness
- 4 Customer Loyalty
- 5 Reputation
- 6 Compliance
- 7 Costs
- Benefits of Using Quality Control in Manufacturing
-
The ZZndash400 manufacturing team drew a scatter diagram to test whether product
purity and iron contamination were related but the plot did not demonstrate a
relationship Then a team member realized that the data came from three different
reactors The team member redrew the diagram using a different symbol for each
reactorrsquos data
Now patterns can be seen The data from reactor 2 and reactor 3 are circled Even
without doing any calculations it is clear that for those two reactors purity decreases
as iron increases However the data from reactor 1 the solid dots that are not circled
do not show that relationship Something is different about reactor 1
Stratification Considerations
Here are examples of different sources that might require data to be stratified
Equipment
Shifts
Departments
24
Materials
Suppliers
Day of the week
Time of day
Products
Survey data usually benefit from stratification
Always consider before collecting data whether stratification might be needed during
analysis Plan to collect stratification information After the data are collected it might
be too late
On your graph or chart include a legend that identifies the marks or colours used
25
Now starting with new 7 quality control tool
Need of new quality control tool
Many customer requirements cannot always be adequately expressed by numerical
data alone Nevertheless even verbal statements can be expressions of facts because
it represents facts we ought to use Verbal data as well as numerical data in
controlling the managing quality It provides both quality control as well as
improvement during the manufacturing process
Benefits of new 7 quality control tool
Combine verbal with Numerical data
Looking for root cause
Clarify prioritize goals and schedule
Involve everyone into full cooperation and generate new ideas 1048577
The first new quality control tool is
1) Affinity Diagram
Application
An affinity diagram is used to organize into groupings large number of ideas opinions
or concerns about a Particular topic
Description
When a large number of ideas opinions or other concerns about a particular topic are
being collected this tool organizes the information into grouping~~based on the
natural relationships that exist among them The process is designed to stimulate
creativity and full participation It works best in groups of limited Size (a maximum
26
of eight members is recommended) in which members are accustomed to working
together This tool is often used to organize ideas generated by brainstorming
Procedure
State the topic to be studied in broad terms(details may prejudice the
response)
Record as many individual ideas opinions or concerns as possible on cards
(one per
card)
Mix the cards and spread them randomly on a large table
Group related cards together as follows
a)sort cards that seem to be related into groups and
b) limit number of grouping to ten without forcing single cards into groups
Locate or create a header card that captures the meaning of each group
Place this header card on top
Transfer the information from cards onto paper organized by groupings
Example For next generation digital camera we can organize the customer
Complains and requirements in an Affinity Diagram1048577
27
Affinity diagram
28
2) Tree diagram
Application
A tree diagram is used to show the interrelation between a topic and its component
elements
Description
A tree diagram systematically breaks down a topic into its component elements Ideas
generated by
Brainstorming and graphed or clustered with an affinity diagram can be converted
into a tree diagram
to show logical and sequential links This tool can be used in planning and problem
solving
Procedure
State the topic to be studied clearly
Define the major categories of the topic(brainstorm or use the header cards
from the affinity diagram)
Construct the diagram by placing the topic in a box on the left-hand side
Branch the major categories laterally to the right
For each major category define the component elements and sub-elements if
any
Laterally branch to the right the component elements and sub-elements for
each major category and
Review the diagram to ensure that there are no gaps in either sequence or
logic
29
30
3) Arrow diagram
Purpose To create a visual presentation of the steps of a process or tasks necessary to
complete a project with special emphasis on the time taken for these activities
Procedure
1 List all the tasks or activities needed to be accomplished before the process of the
project
2 Decide which steps are undertaken in series and which steps can be run in parallel
Arrange the
Activities in a proper sequence
3 Prepare lsquoEvent Nodesrsquo at the completion of steps and number them
4 Write the description of the step and decide the time required for completing each
step
5 Calculate the earliest time to reach an event node for the start of the process
7 Ager the time for all event nodes including the completion of the process or the
project is available one calculates the latest time by which an event node must be
reached
Application
The diagram is also useful in planning and scheduling steps in complicated processes
especially in planning and scheduling projects which involve a large number of
activities
Example
31
1 Identify the tasks Eg 123hellip15
2 Know the time each task needs
3 Determine which tasks can be run in parallel and in normal sequences
4 Draw the sequence diagram and find the critical path
5 Calculate the project duration
6 Calculate the earliest starting time (or the earliest finishing time of last task) and the
latest finishing time
of each task(the latest starting time for the following task)
7 Mark the time indication
32
33
4) Process Decision Program Chart (PDPC)
Def The process decision program chart (PDPC) method helps us select the best
processes to obtain optimum results by evaluating the progress of events and various
conceivable outcomes
Description
The process decision program chart (PDPC) method is used to define the solution
process when dealing with problems that have more than one possible outcome [t
anticipates the unexpected Outcomes at each stage and plans for it
PDPC has two following patterns
Pattern I ndash In this pattern process starts with initial condition lsquoArsquo and proceeds to the
desired final condition lsquoZrsquo in an organized manner
Pattern 11- In this pattern first the final conditionrsquosrsquo is set Then the process from lsquoZrsquo
to the initial point lsquoArsquo is developed with the inclusion of various alternatives from
many points of view
Procedure
Discuss the issues related to the project among a cross-functional team
Discuss which issues must be examined and identify those issues
Consider and note down all the anticipated results for the identified issues
Weigh the feasibility of each solution proposed and investigate alternate
solutions
Classify each issue according to its urgency number of operations required
likelihood of Occurrence and difficulty
Consider the anticipated results and alternative solutions related to issues that
must be addressed immediately and link the items with arrows to the desired
goal
34
Prioritize the different issues and consider them all together Information
related to one set of
Possibilities could influence another set Related items shall be linked with a
broken line
If the department that will handle a process involving several lines is
determined circle
the process and write the name of the department within
Set a target date for completion
Have regular meetings to check progress in terms of the original PDPC
35
36
37
38
5) Matrix diagram
Purpose1) Explore the existence and the extent of relations between individual items in 2 sets
of factors or features and characteristics and express them in a symbolic form that is
easy to understand
2) Mostly used to understand the relations between the customer expectations as
expressed by the customers and product characteristics as designed manufactured and
tested by the manufacturer
Procedures1 Determine 2 sets of factors for which the relations are needed to be established
2 Divide the features and characteristics into primary secondary and tertiary
characteristics
3 Place the features vertically on the leg side of the matrix and characteristics
horizontally on top of the matrix
4 Enter the importance of the features on the column ager that for the tertiary
features10485775 In the main body of the matrix use the symbols to represent the degree of
connections between the feature and characteristics
6 Choose and define relationship symbols Most commonly used symbols are as
given below
Strong relationship=
Relationship =
Likely relationship=
Application
bull Matrix diagram can be used to solve problems by arranging data in such a way that
the relations between relevant factors are brought into sharp focus
bull There is no limit to the use of the tool
39
bull The most important application of matrix diagram is in clarifying relations between
individual features of customer requirements and individual product characteristics
Example 1
Matrix Diagram for Quality Functions and Responsibilities
40
41
6) Matrix Data Analysis Diagram1048577
Purpose
To present numerical data about two sets of factors in a matrix form and
analyze it to get numerical output
Can be applied in understanding the products and products characteristics
Procedure1048577
1 Decide the two factors whose relations are to be analyzed
2 Check the number of individual items in the two factors
3 Prepare a matrix to accommodate all the items of the two factors
4 Enter numerical data in the matrix
5 Give the diagram a suitable title
Example
42
43
44
7) Relationship diagram
This diagram clarifies the interrelations in a complex situation involving many
interrelated factors and serves to clarify the cause and effect relationships among
factors
Description
Relations diagram is defined as a technique used to solve problems that have complex
cause and effect relationships among a number of problems and factors that influence
them
Format
A special feature of relation diagram is its unrestricted Format However general
formats are as given below
1) Centrally converging relations diagram
The major item or problem to be solved is located in the center and the related factors
are arranged around the item or problem in such a way as to indicate close
relationships
2) Directionally intensive relations diagram
The major item or problem to be solved is located on one side of the diagram and the
various factors arranged in accordance with the flow of their major cause-and-effect
relationships on the other side
3) Relationship indication relations diagram
There are no restrictions on this format because the main point is to arrange the cause-
and-effect Relationships of the application items or factors so that they are expressed
in a straightforward manner in a Diagram
45
Procedure
1) Define the issueproblem in such a way that it is clearly understood and agreed on
by team members
2) Assemble the cross-functional team
3) Layout all the ideasissue cards that have been brought from other tools
4) Look for causeinfluence relationships between all ideas and draw relationship
arrows
a) Choose any of the ideas as a starting point and work through them in sequence
b)An outgoing arrow from an idea indicates that it is the stronger cause or influence
c) Draw only one way relationship arrows in the direction of the stronger cause or
Influence Make a decision on the stronger direction Do not draw two headed arrows
5) Review and revise the relationsrsquo diagram
6) Tally the number of outgoing and incoming arrows and select key items for further
planning
-record and clearly mark next to each issue the number of arrows going in and out of
it
-find the items with the highest number outgoing arrows and the items with the
highest number of incoming arrows
-a high number of outgoing arrows indicate that the item is a root cause and should be
tackle first
46
-a high number of incoming arrows indicate that the item is a key outcome and may
become a focus for planning either as a meaningful measure of overall success or as a
redefinition of the original issue under discussion
Example
47
48
Conclusions
Statististical QC is chiefly concerned in making sure that several procedures
and working arrangements are in place to provide for effective and efficient
statistical processes to minimize the risk of errors or weaknesses in
procedures or systems or in source material
Seven QC tools are most helpful in troubleshooting issues related to quality
All processes are affected by multiple factors and therefore statistical QC tools
can be applied to any process
The continuous use of these tools upgrades the personnel characteristics of the
people involved It enhances their ability to think generate ideas solve
problem and do proper planning
49
References asqorglearn-about-qualityseven-basic-quality-toolsoverviewhtml
httpsenwikipediaorgwikiSeven_Basic_Tools_of_Quality
wwwijergsorgfilesdocumentsAPPLICATION-45pd
httpssrcalionsciencecompdfQualityToolspdf
www3haorghkqehwiserdoc7bqtpdf
wwwmathmunca~variyathNew7QCToolspd
50
- 1 DEFINITION of Quality Control
- 3 Competitiveness
- 4 Customer Loyalty
- 5 Reputation
- 6 Compliance
- 7 Costs
- Benefits of Using Quality Control in Manufacturing
-
Materials
Suppliers
Day of the week
Time of day
Products
Survey data usually benefit from stratification
Always consider before collecting data whether stratification might be needed during
analysis Plan to collect stratification information After the data are collected it might
be too late
On your graph or chart include a legend that identifies the marks or colours used
25
Now starting with new 7 quality control tool
Need of new quality control tool
Many customer requirements cannot always be adequately expressed by numerical
data alone Nevertheless even verbal statements can be expressions of facts because
it represents facts we ought to use Verbal data as well as numerical data in
controlling the managing quality It provides both quality control as well as
improvement during the manufacturing process
Benefits of new 7 quality control tool
Combine verbal with Numerical data
Looking for root cause
Clarify prioritize goals and schedule
Involve everyone into full cooperation and generate new ideas 1048577
The first new quality control tool is
1) Affinity Diagram
Application
An affinity diagram is used to organize into groupings large number of ideas opinions
or concerns about a Particular topic
Description
When a large number of ideas opinions or other concerns about a particular topic are
being collected this tool organizes the information into grouping~~based on the
natural relationships that exist among them The process is designed to stimulate
creativity and full participation It works best in groups of limited Size (a maximum
26
of eight members is recommended) in which members are accustomed to working
together This tool is often used to organize ideas generated by brainstorming
Procedure
State the topic to be studied in broad terms(details may prejudice the
response)
Record as many individual ideas opinions or concerns as possible on cards
(one per
card)
Mix the cards and spread them randomly on a large table
Group related cards together as follows
a)sort cards that seem to be related into groups and
b) limit number of grouping to ten without forcing single cards into groups
Locate or create a header card that captures the meaning of each group
Place this header card on top
Transfer the information from cards onto paper organized by groupings
Example For next generation digital camera we can organize the customer
Complains and requirements in an Affinity Diagram1048577
27
Affinity diagram
28
2) Tree diagram
Application
A tree diagram is used to show the interrelation between a topic and its component
elements
Description
A tree diagram systematically breaks down a topic into its component elements Ideas
generated by
Brainstorming and graphed or clustered with an affinity diagram can be converted
into a tree diagram
to show logical and sequential links This tool can be used in planning and problem
solving
Procedure
State the topic to be studied clearly
Define the major categories of the topic(brainstorm or use the header cards
from the affinity diagram)
Construct the diagram by placing the topic in a box on the left-hand side
Branch the major categories laterally to the right
For each major category define the component elements and sub-elements if
any
Laterally branch to the right the component elements and sub-elements for
each major category and
Review the diagram to ensure that there are no gaps in either sequence or
logic
29
30
3) Arrow diagram
Purpose To create a visual presentation of the steps of a process or tasks necessary to
complete a project with special emphasis on the time taken for these activities
Procedure
1 List all the tasks or activities needed to be accomplished before the process of the
project
2 Decide which steps are undertaken in series and which steps can be run in parallel
Arrange the
Activities in a proper sequence
3 Prepare lsquoEvent Nodesrsquo at the completion of steps and number them
4 Write the description of the step and decide the time required for completing each
step
5 Calculate the earliest time to reach an event node for the start of the process
7 Ager the time for all event nodes including the completion of the process or the
project is available one calculates the latest time by which an event node must be
reached
Application
The diagram is also useful in planning and scheduling steps in complicated processes
especially in planning and scheduling projects which involve a large number of
activities
Example
31
1 Identify the tasks Eg 123hellip15
2 Know the time each task needs
3 Determine which tasks can be run in parallel and in normal sequences
4 Draw the sequence diagram and find the critical path
5 Calculate the project duration
6 Calculate the earliest starting time (or the earliest finishing time of last task) and the
latest finishing time
of each task(the latest starting time for the following task)
7 Mark the time indication
32
33
4) Process Decision Program Chart (PDPC)
Def The process decision program chart (PDPC) method helps us select the best
processes to obtain optimum results by evaluating the progress of events and various
conceivable outcomes
Description
The process decision program chart (PDPC) method is used to define the solution
process when dealing with problems that have more than one possible outcome [t
anticipates the unexpected Outcomes at each stage and plans for it
PDPC has two following patterns
Pattern I ndash In this pattern process starts with initial condition lsquoArsquo and proceeds to the
desired final condition lsquoZrsquo in an organized manner
Pattern 11- In this pattern first the final conditionrsquosrsquo is set Then the process from lsquoZrsquo
to the initial point lsquoArsquo is developed with the inclusion of various alternatives from
many points of view
Procedure
Discuss the issues related to the project among a cross-functional team
Discuss which issues must be examined and identify those issues
Consider and note down all the anticipated results for the identified issues
Weigh the feasibility of each solution proposed and investigate alternate
solutions
Classify each issue according to its urgency number of operations required
likelihood of Occurrence and difficulty
Consider the anticipated results and alternative solutions related to issues that
must be addressed immediately and link the items with arrows to the desired
goal
34
Prioritize the different issues and consider them all together Information
related to one set of
Possibilities could influence another set Related items shall be linked with a
broken line
If the department that will handle a process involving several lines is
determined circle
the process and write the name of the department within
Set a target date for completion
Have regular meetings to check progress in terms of the original PDPC
35
36
37
38
5) Matrix diagram
Purpose1) Explore the existence and the extent of relations between individual items in 2 sets
of factors or features and characteristics and express them in a symbolic form that is
easy to understand
2) Mostly used to understand the relations between the customer expectations as
expressed by the customers and product characteristics as designed manufactured and
tested by the manufacturer
Procedures1 Determine 2 sets of factors for which the relations are needed to be established
2 Divide the features and characteristics into primary secondary and tertiary
characteristics
3 Place the features vertically on the leg side of the matrix and characteristics
horizontally on top of the matrix
4 Enter the importance of the features on the column ager that for the tertiary
features10485775 In the main body of the matrix use the symbols to represent the degree of
connections between the feature and characteristics
6 Choose and define relationship symbols Most commonly used symbols are as
given below
Strong relationship=
Relationship =
Likely relationship=
Application
bull Matrix diagram can be used to solve problems by arranging data in such a way that
the relations between relevant factors are brought into sharp focus
bull There is no limit to the use of the tool
39
bull The most important application of matrix diagram is in clarifying relations between
individual features of customer requirements and individual product characteristics
Example 1
Matrix Diagram for Quality Functions and Responsibilities
40
41
6) Matrix Data Analysis Diagram1048577
Purpose
To present numerical data about two sets of factors in a matrix form and
analyze it to get numerical output
Can be applied in understanding the products and products characteristics
Procedure1048577
1 Decide the two factors whose relations are to be analyzed
2 Check the number of individual items in the two factors
3 Prepare a matrix to accommodate all the items of the two factors
4 Enter numerical data in the matrix
5 Give the diagram a suitable title
Example
42
43
44
7) Relationship diagram
This diagram clarifies the interrelations in a complex situation involving many
interrelated factors and serves to clarify the cause and effect relationships among
factors
Description
Relations diagram is defined as a technique used to solve problems that have complex
cause and effect relationships among a number of problems and factors that influence
them
Format
A special feature of relation diagram is its unrestricted Format However general
formats are as given below
1) Centrally converging relations diagram
The major item or problem to be solved is located in the center and the related factors
are arranged around the item or problem in such a way as to indicate close
relationships
2) Directionally intensive relations diagram
The major item or problem to be solved is located on one side of the diagram and the
various factors arranged in accordance with the flow of their major cause-and-effect
relationships on the other side
3) Relationship indication relations diagram
There are no restrictions on this format because the main point is to arrange the cause-
and-effect Relationships of the application items or factors so that they are expressed
in a straightforward manner in a Diagram
45
Procedure
1) Define the issueproblem in such a way that it is clearly understood and agreed on
by team members
2) Assemble the cross-functional team
3) Layout all the ideasissue cards that have been brought from other tools
4) Look for causeinfluence relationships between all ideas and draw relationship
arrows
a) Choose any of the ideas as a starting point and work through them in sequence
b)An outgoing arrow from an idea indicates that it is the stronger cause or influence
c) Draw only one way relationship arrows in the direction of the stronger cause or
Influence Make a decision on the stronger direction Do not draw two headed arrows
5) Review and revise the relationsrsquo diagram
6) Tally the number of outgoing and incoming arrows and select key items for further
planning
-record and clearly mark next to each issue the number of arrows going in and out of
it
-find the items with the highest number outgoing arrows and the items with the
highest number of incoming arrows
-a high number of outgoing arrows indicate that the item is a root cause and should be
tackle first
46
-a high number of incoming arrows indicate that the item is a key outcome and may
become a focus for planning either as a meaningful measure of overall success or as a
redefinition of the original issue under discussion
Example
47
48
Conclusions
Statististical QC is chiefly concerned in making sure that several procedures
and working arrangements are in place to provide for effective and efficient
statistical processes to minimize the risk of errors or weaknesses in
procedures or systems or in source material
Seven QC tools are most helpful in troubleshooting issues related to quality
All processes are affected by multiple factors and therefore statistical QC tools
can be applied to any process
The continuous use of these tools upgrades the personnel characteristics of the
people involved It enhances their ability to think generate ideas solve
problem and do proper planning
49
References asqorglearn-about-qualityseven-basic-quality-toolsoverviewhtml
httpsenwikipediaorgwikiSeven_Basic_Tools_of_Quality
wwwijergsorgfilesdocumentsAPPLICATION-45pd
httpssrcalionsciencecompdfQualityToolspdf
www3haorghkqehwiserdoc7bqtpdf
wwwmathmunca~variyathNew7QCToolspd
50
- 1 DEFINITION of Quality Control
- 3 Competitiveness
- 4 Customer Loyalty
- 5 Reputation
- 6 Compliance
- 7 Costs
- Benefits of Using Quality Control in Manufacturing
-
Now starting with new 7 quality control tool
Need of new quality control tool
Many customer requirements cannot always be adequately expressed by numerical
data alone Nevertheless even verbal statements can be expressions of facts because
it represents facts we ought to use Verbal data as well as numerical data in
controlling the managing quality It provides both quality control as well as
improvement during the manufacturing process
Benefits of new 7 quality control tool
Combine verbal with Numerical data
Looking for root cause
Clarify prioritize goals and schedule
Involve everyone into full cooperation and generate new ideas 1048577
The first new quality control tool is
1) Affinity Diagram
Application
An affinity diagram is used to organize into groupings large number of ideas opinions
or concerns about a Particular topic
Description
When a large number of ideas opinions or other concerns about a particular topic are
being collected this tool organizes the information into grouping~~based on the
natural relationships that exist among them The process is designed to stimulate
creativity and full participation It works best in groups of limited Size (a maximum
26
of eight members is recommended) in which members are accustomed to working
together This tool is often used to organize ideas generated by brainstorming
Procedure
State the topic to be studied in broad terms(details may prejudice the
response)
Record as many individual ideas opinions or concerns as possible on cards
(one per
card)
Mix the cards and spread them randomly on a large table
Group related cards together as follows
a)sort cards that seem to be related into groups and
b) limit number of grouping to ten without forcing single cards into groups
Locate or create a header card that captures the meaning of each group
Place this header card on top
Transfer the information from cards onto paper organized by groupings
Example For next generation digital camera we can organize the customer
Complains and requirements in an Affinity Diagram1048577
27
Affinity diagram
28
2) Tree diagram
Application
A tree diagram is used to show the interrelation between a topic and its component
elements
Description
A tree diagram systematically breaks down a topic into its component elements Ideas
generated by
Brainstorming and graphed or clustered with an affinity diagram can be converted
into a tree diagram
to show logical and sequential links This tool can be used in planning and problem
solving
Procedure
State the topic to be studied clearly
Define the major categories of the topic(brainstorm or use the header cards
from the affinity diagram)
Construct the diagram by placing the topic in a box on the left-hand side
Branch the major categories laterally to the right
For each major category define the component elements and sub-elements if
any
Laterally branch to the right the component elements and sub-elements for
each major category and
Review the diagram to ensure that there are no gaps in either sequence or
logic
29
30
3) Arrow diagram
Purpose To create a visual presentation of the steps of a process or tasks necessary to
complete a project with special emphasis on the time taken for these activities
Procedure
1 List all the tasks or activities needed to be accomplished before the process of the
project
2 Decide which steps are undertaken in series and which steps can be run in parallel
Arrange the
Activities in a proper sequence
3 Prepare lsquoEvent Nodesrsquo at the completion of steps and number them
4 Write the description of the step and decide the time required for completing each
step
5 Calculate the earliest time to reach an event node for the start of the process
7 Ager the time for all event nodes including the completion of the process or the
project is available one calculates the latest time by which an event node must be
reached
Application
The diagram is also useful in planning and scheduling steps in complicated processes
especially in planning and scheduling projects which involve a large number of
activities
Example
31
1 Identify the tasks Eg 123hellip15
2 Know the time each task needs
3 Determine which tasks can be run in parallel and in normal sequences
4 Draw the sequence diagram and find the critical path
5 Calculate the project duration
6 Calculate the earliest starting time (or the earliest finishing time of last task) and the
latest finishing time
of each task(the latest starting time for the following task)
7 Mark the time indication
32
33
4) Process Decision Program Chart (PDPC)
Def The process decision program chart (PDPC) method helps us select the best
processes to obtain optimum results by evaluating the progress of events and various
conceivable outcomes
Description
The process decision program chart (PDPC) method is used to define the solution
process when dealing with problems that have more than one possible outcome [t
anticipates the unexpected Outcomes at each stage and plans for it
PDPC has two following patterns
Pattern I ndash In this pattern process starts with initial condition lsquoArsquo and proceeds to the
desired final condition lsquoZrsquo in an organized manner
Pattern 11- In this pattern first the final conditionrsquosrsquo is set Then the process from lsquoZrsquo
to the initial point lsquoArsquo is developed with the inclusion of various alternatives from
many points of view
Procedure
Discuss the issues related to the project among a cross-functional team
Discuss which issues must be examined and identify those issues
Consider and note down all the anticipated results for the identified issues
Weigh the feasibility of each solution proposed and investigate alternate
solutions
Classify each issue according to its urgency number of operations required
likelihood of Occurrence and difficulty
Consider the anticipated results and alternative solutions related to issues that
must be addressed immediately and link the items with arrows to the desired
goal
34
Prioritize the different issues and consider them all together Information
related to one set of
Possibilities could influence another set Related items shall be linked with a
broken line
If the department that will handle a process involving several lines is
determined circle
the process and write the name of the department within
Set a target date for completion
Have regular meetings to check progress in terms of the original PDPC
35
36
37
38
5) Matrix diagram
Purpose1) Explore the existence and the extent of relations between individual items in 2 sets
of factors or features and characteristics and express them in a symbolic form that is
easy to understand
2) Mostly used to understand the relations between the customer expectations as
expressed by the customers and product characteristics as designed manufactured and
tested by the manufacturer
Procedures1 Determine 2 sets of factors for which the relations are needed to be established
2 Divide the features and characteristics into primary secondary and tertiary
characteristics
3 Place the features vertically on the leg side of the matrix and characteristics
horizontally on top of the matrix
4 Enter the importance of the features on the column ager that for the tertiary
features10485775 In the main body of the matrix use the symbols to represent the degree of
connections between the feature and characteristics
6 Choose and define relationship symbols Most commonly used symbols are as
given below
Strong relationship=
Relationship =
Likely relationship=
Application
bull Matrix diagram can be used to solve problems by arranging data in such a way that
the relations between relevant factors are brought into sharp focus
bull There is no limit to the use of the tool
39
bull The most important application of matrix diagram is in clarifying relations between
individual features of customer requirements and individual product characteristics
Example 1
Matrix Diagram for Quality Functions and Responsibilities
40
41
6) Matrix Data Analysis Diagram1048577
Purpose
To present numerical data about two sets of factors in a matrix form and
analyze it to get numerical output
Can be applied in understanding the products and products characteristics
Procedure1048577
1 Decide the two factors whose relations are to be analyzed
2 Check the number of individual items in the two factors
3 Prepare a matrix to accommodate all the items of the two factors
4 Enter numerical data in the matrix
5 Give the diagram a suitable title
Example
42
43
44
7) Relationship diagram
This diagram clarifies the interrelations in a complex situation involving many
interrelated factors and serves to clarify the cause and effect relationships among
factors
Description
Relations diagram is defined as a technique used to solve problems that have complex
cause and effect relationships among a number of problems and factors that influence
them
Format
A special feature of relation diagram is its unrestricted Format However general
formats are as given below
1) Centrally converging relations diagram
The major item or problem to be solved is located in the center and the related factors
are arranged around the item or problem in such a way as to indicate close
relationships
2) Directionally intensive relations diagram
The major item or problem to be solved is located on one side of the diagram and the
various factors arranged in accordance with the flow of their major cause-and-effect
relationships on the other side
3) Relationship indication relations diagram
There are no restrictions on this format because the main point is to arrange the cause-
and-effect Relationships of the application items or factors so that they are expressed
in a straightforward manner in a Diagram
45
Procedure
1) Define the issueproblem in such a way that it is clearly understood and agreed on
by team members
2) Assemble the cross-functional team
3) Layout all the ideasissue cards that have been brought from other tools
4) Look for causeinfluence relationships between all ideas and draw relationship
arrows
a) Choose any of the ideas as a starting point and work through them in sequence
b)An outgoing arrow from an idea indicates that it is the stronger cause or influence
c) Draw only one way relationship arrows in the direction of the stronger cause or
Influence Make a decision on the stronger direction Do not draw two headed arrows
5) Review and revise the relationsrsquo diagram
6) Tally the number of outgoing and incoming arrows and select key items for further
planning
-record and clearly mark next to each issue the number of arrows going in and out of
it
-find the items with the highest number outgoing arrows and the items with the
highest number of incoming arrows
-a high number of outgoing arrows indicate that the item is a root cause and should be
tackle first
46
-a high number of incoming arrows indicate that the item is a key outcome and may
become a focus for planning either as a meaningful measure of overall success or as a
redefinition of the original issue under discussion
Example
47
48
Conclusions
Statististical QC is chiefly concerned in making sure that several procedures
and working arrangements are in place to provide for effective and efficient
statistical processes to minimize the risk of errors or weaknesses in
procedures or systems or in source material
Seven QC tools are most helpful in troubleshooting issues related to quality
All processes are affected by multiple factors and therefore statistical QC tools
can be applied to any process
The continuous use of these tools upgrades the personnel characteristics of the
people involved It enhances their ability to think generate ideas solve
problem and do proper planning
49
References asqorglearn-about-qualityseven-basic-quality-toolsoverviewhtml
httpsenwikipediaorgwikiSeven_Basic_Tools_of_Quality
wwwijergsorgfilesdocumentsAPPLICATION-45pd
httpssrcalionsciencecompdfQualityToolspdf
www3haorghkqehwiserdoc7bqtpdf
wwwmathmunca~variyathNew7QCToolspd
50
- 1 DEFINITION of Quality Control
- 3 Competitiveness
- 4 Customer Loyalty
- 5 Reputation
- 6 Compliance
- 7 Costs
- Benefits of Using Quality Control in Manufacturing
-
of eight members is recommended) in which members are accustomed to working
together This tool is often used to organize ideas generated by brainstorming
Procedure
State the topic to be studied in broad terms(details may prejudice the
response)
Record as many individual ideas opinions or concerns as possible on cards
(one per
card)
Mix the cards and spread them randomly on a large table
Group related cards together as follows
a)sort cards that seem to be related into groups and
b) limit number of grouping to ten without forcing single cards into groups
Locate or create a header card that captures the meaning of each group
Place this header card on top
Transfer the information from cards onto paper organized by groupings
Example For next generation digital camera we can organize the customer
Complains and requirements in an Affinity Diagram1048577
27
Affinity diagram
28
2) Tree diagram
Application
A tree diagram is used to show the interrelation between a topic and its component
elements
Description
A tree diagram systematically breaks down a topic into its component elements Ideas
generated by
Brainstorming and graphed or clustered with an affinity diagram can be converted
into a tree diagram
to show logical and sequential links This tool can be used in planning and problem
solving
Procedure
State the topic to be studied clearly
Define the major categories of the topic(brainstorm or use the header cards
from the affinity diagram)
Construct the diagram by placing the topic in a box on the left-hand side
Branch the major categories laterally to the right
For each major category define the component elements and sub-elements if
any
Laterally branch to the right the component elements and sub-elements for
each major category and
Review the diagram to ensure that there are no gaps in either sequence or
logic
29
30
3) Arrow diagram
Purpose To create a visual presentation of the steps of a process or tasks necessary to
complete a project with special emphasis on the time taken for these activities
Procedure
1 List all the tasks or activities needed to be accomplished before the process of the
project
2 Decide which steps are undertaken in series and which steps can be run in parallel
Arrange the
Activities in a proper sequence
3 Prepare lsquoEvent Nodesrsquo at the completion of steps and number them
4 Write the description of the step and decide the time required for completing each
step
5 Calculate the earliest time to reach an event node for the start of the process
7 Ager the time for all event nodes including the completion of the process or the
project is available one calculates the latest time by which an event node must be
reached
Application
The diagram is also useful in planning and scheduling steps in complicated processes
especially in planning and scheduling projects which involve a large number of
activities
Example
31
1 Identify the tasks Eg 123hellip15
2 Know the time each task needs
3 Determine which tasks can be run in parallel and in normal sequences
4 Draw the sequence diagram and find the critical path
5 Calculate the project duration
6 Calculate the earliest starting time (or the earliest finishing time of last task) and the
latest finishing time
of each task(the latest starting time for the following task)
7 Mark the time indication
32
33
4) Process Decision Program Chart (PDPC)
Def The process decision program chart (PDPC) method helps us select the best
processes to obtain optimum results by evaluating the progress of events and various
conceivable outcomes
Description
The process decision program chart (PDPC) method is used to define the solution
process when dealing with problems that have more than one possible outcome [t
anticipates the unexpected Outcomes at each stage and plans for it
PDPC has two following patterns
Pattern I ndash In this pattern process starts with initial condition lsquoArsquo and proceeds to the
desired final condition lsquoZrsquo in an organized manner
Pattern 11- In this pattern first the final conditionrsquosrsquo is set Then the process from lsquoZrsquo
to the initial point lsquoArsquo is developed with the inclusion of various alternatives from
many points of view
Procedure
Discuss the issues related to the project among a cross-functional team
Discuss which issues must be examined and identify those issues
Consider and note down all the anticipated results for the identified issues
Weigh the feasibility of each solution proposed and investigate alternate
solutions
Classify each issue according to its urgency number of operations required
likelihood of Occurrence and difficulty
Consider the anticipated results and alternative solutions related to issues that
must be addressed immediately and link the items with arrows to the desired
goal
34
Prioritize the different issues and consider them all together Information
related to one set of
Possibilities could influence another set Related items shall be linked with a
broken line
If the department that will handle a process involving several lines is
determined circle
the process and write the name of the department within
Set a target date for completion
Have regular meetings to check progress in terms of the original PDPC
35
36
37
38
5) Matrix diagram
Purpose1) Explore the existence and the extent of relations between individual items in 2 sets
of factors or features and characteristics and express them in a symbolic form that is
easy to understand
2) Mostly used to understand the relations between the customer expectations as
expressed by the customers and product characteristics as designed manufactured and
tested by the manufacturer
Procedures1 Determine 2 sets of factors for which the relations are needed to be established
2 Divide the features and characteristics into primary secondary and tertiary
characteristics
3 Place the features vertically on the leg side of the matrix and characteristics
horizontally on top of the matrix
4 Enter the importance of the features on the column ager that for the tertiary
features10485775 In the main body of the matrix use the symbols to represent the degree of
connections between the feature and characteristics
6 Choose and define relationship symbols Most commonly used symbols are as
given below
Strong relationship=
Relationship =
Likely relationship=
Application
bull Matrix diagram can be used to solve problems by arranging data in such a way that
the relations between relevant factors are brought into sharp focus
bull There is no limit to the use of the tool
39
bull The most important application of matrix diagram is in clarifying relations between
individual features of customer requirements and individual product characteristics
Example 1
Matrix Diagram for Quality Functions and Responsibilities
40
41
6) Matrix Data Analysis Diagram1048577
Purpose
To present numerical data about two sets of factors in a matrix form and
analyze it to get numerical output
Can be applied in understanding the products and products characteristics
Procedure1048577
1 Decide the two factors whose relations are to be analyzed
2 Check the number of individual items in the two factors
3 Prepare a matrix to accommodate all the items of the two factors
4 Enter numerical data in the matrix
5 Give the diagram a suitable title
Example
42
43
44
7) Relationship diagram
This diagram clarifies the interrelations in a complex situation involving many
interrelated factors and serves to clarify the cause and effect relationships among
factors
Description
Relations diagram is defined as a technique used to solve problems that have complex
cause and effect relationships among a number of problems and factors that influence
them
Format
A special feature of relation diagram is its unrestricted Format However general
formats are as given below
1) Centrally converging relations diagram
The major item or problem to be solved is located in the center and the related factors
are arranged around the item or problem in such a way as to indicate close
relationships
2) Directionally intensive relations diagram
The major item or problem to be solved is located on one side of the diagram and the
various factors arranged in accordance with the flow of their major cause-and-effect
relationships on the other side
3) Relationship indication relations diagram
There are no restrictions on this format because the main point is to arrange the cause-
and-effect Relationships of the application items or factors so that they are expressed
in a straightforward manner in a Diagram
45
Procedure
1) Define the issueproblem in such a way that it is clearly understood and agreed on
by team members
2) Assemble the cross-functional team
3) Layout all the ideasissue cards that have been brought from other tools
4) Look for causeinfluence relationships between all ideas and draw relationship
arrows
a) Choose any of the ideas as a starting point and work through them in sequence
b)An outgoing arrow from an idea indicates that it is the stronger cause or influence
c) Draw only one way relationship arrows in the direction of the stronger cause or
Influence Make a decision on the stronger direction Do not draw two headed arrows
5) Review and revise the relationsrsquo diagram
6) Tally the number of outgoing and incoming arrows and select key items for further
planning
-record and clearly mark next to each issue the number of arrows going in and out of
it
-find the items with the highest number outgoing arrows and the items with the
highest number of incoming arrows
-a high number of outgoing arrows indicate that the item is a root cause and should be
tackle first
46
-a high number of incoming arrows indicate that the item is a key outcome and may
become a focus for planning either as a meaningful measure of overall success or as a
redefinition of the original issue under discussion
Example
47
48
Conclusions
Statististical QC is chiefly concerned in making sure that several procedures
and working arrangements are in place to provide for effective and efficient
statistical processes to minimize the risk of errors or weaknesses in
procedures or systems or in source material
Seven QC tools are most helpful in troubleshooting issues related to quality
All processes are affected by multiple factors and therefore statistical QC tools
can be applied to any process
The continuous use of these tools upgrades the personnel characteristics of the
people involved It enhances their ability to think generate ideas solve
problem and do proper planning
49
References asqorglearn-about-qualityseven-basic-quality-toolsoverviewhtml
httpsenwikipediaorgwikiSeven_Basic_Tools_of_Quality
wwwijergsorgfilesdocumentsAPPLICATION-45pd
httpssrcalionsciencecompdfQualityToolspdf
www3haorghkqehwiserdoc7bqtpdf
wwwmathmunca~variyathNew7QCToolspd
50
- 1 DEFINITION of Quality Control
- 3 Competitiveness
- 4 Customer Loyalty
- 5 Reputation
- 6 Compliance
- 7 Costs
- Benefits of Using Quality Control in Manufacturing
-
Affinity diagram
28
2) Tree diagram
Application
A tree diagram is used to show the interrelation between a topic and its component
elements
Description
A tree diagram systematically breaks down a topic into its component elements Ideas
generated by
Brainstorming and graphed or clustered with an affinity diagram can be converted
into a tree diagram
to show logical and sequential links This tool can be used in planning and problem
solving
Procedure
State the topic to be studied clearly
Define the major categories of the topic(brainstorm or use the header cards
from the affinity diagram)
Construct the diagram by placing the topic in a box on the left-hand side
Branch the major categories laterally to the right
For each major category define the component elements and sub-elements if
any
Laterally branch to the right the component elements and sub-elements for
each major category and
Review the diagram to ensure that there are no gaps in either sequence or
logic
29
30
3) Arrow diagram
Purpose To create a visual presentation of the steps of a process or tasks necessary to
complete a project with special emphasis on the time taken for these activities
Procedure
1 List all the tasks or activities needed to be accomplished before the process of the
project
2 Decide which steps are undertaken in series and which steps can be run in parallel
Arrange the
Activities in a proper sequence
3 Prepare lsquoEvent Nodesrsquo at the completion of steps and number them
4 Write the description of the step and decide the time required for completing each
step
5 Calculate the earliest time to reach an event node for the start of the process
7 Ager the time for all event nodes including the completion of the process or the
project is available one calculates the latest time by which an event node must be
reached
Application
The diagram is also useful in planning and scheduling steps in complicated processes
especially in planning and scheduling projects which involve a large number of
activities
Example
31
1 Identify the tasks Eg 123hellip15
2 Know the time each task needs
3 Determine which tasks can be run in parallel and in normal sequences
4 Draw the sequence diagram and find the critical path
5 Calculate the project duration
6 Calculate the earliest starting time (or the earliest finishing time of last task) and the
latest finishing time
of each task(the latest starting time for the following task)
7 Mark the time indication
32
33
4) Process Decision Program Chart (PDPC)
Def The process decision program chart (PDPC) method helps us select the best
processes to obtain optimum results by evaluating the progress of events and various
conceivable outcomes
Description
The process decision program chart (PDPC) method is used to define the solution
process when dealing with problems that have more than one possible outcome [t
anticipates the unexpected Outcomes at each stage and plans for it
PDPC has two following patterns
Pattern I ndash In this pattern process starts with initial condition lsquoArsquo and proceeds to the
desired final condition lsquoZrsquo in an organized manner
Pattern 11- In this pattern first the final conditionrsquosrsquo is set Then the process from lsquoZrsquo
to the initial point lsquoArsquo is developed with the inclusion of various alternatives from
many points of view
Procedure
Discuss the issues related to the project among a cross-functional team
Discuss which issues must be examined and identify those issues
Consider and note down all the anticipated results for the identified issues
Weigh the feasibility of each solution proposed and investigate alternate
solutions
Classify each issue according to its urgency number of operations required
likelihood of Occurrence and difficulty
Consider the anticipated results and alternative solutions related to issues that
must be addressed immediately and link the items with arrows to the desired
goal
34
Prioritize the different issues and consider them all together Information
related to one set of
Possibilities could influence another set Related items shall be linked with a
broken line
If the department that will handle a process involving several lines is
determined circle
the process and write the name of the department within
Set a target date for completion
Have regular meetings to check progress in terms of the original PDPC
35
36
37
38
5) Matrix diagram
Purpose1) Explore the existence and the extent of relations between individual items in 2 sets
of factors or features and characteristics and express them in a symbolic form that is
easy to understand
2) Mostly used to understand the relations between the customer expectations as
expressed by the customers and product characteristics as designed manufactured and
tested by the manufacturer
Procedures1 Determine 2 sets of factors for which the relations are needed to be established
2 Divide the features and characteristics into primary secondary and tertiary
characteristics
3 Place the features vertically on the leg side of the matrix and characteristics
horizontally on top of the matrix
4 Enter the importance of the features on the column ager that for the tertiary
features10485775 In the main body of the matrix use the symbols to represent the degree of
connections between the feature and characteristics
6 Choose and define relationship symbols Most commonly used symbols are as
given below
Strong relationship=
Relationship =
Likely relationship=
Application
bull Matrix diagram can be used to solve problems by arranging data in such a way that
the relations between relevant factors are brought into sharp focus
bull There is no limit to the use of the tool
39
bull The most important application of matrix diagram is in clarifying relations between
individual features of customer requirements and individual product characteristics
Example 1
Matrix Diagram for Quality Functions and Responsibilities
40
41
6) Matrix Data Analysis Diagram1048577
Purpose
To present numerical data about two sets of factors in a matrix form and
analyze it to get numerical output
Can be applied in understanding the products and products characteristics
Procedure1048577
1 Decide the two factors whose relations are to be analyzed
2 Check the number of individual items in the two factors
3 Prepare a matrix to accommodate all the items of the two factors
4 Enter numerical data in the matrix
5 Give the diagram a suitable title
Example
42
43
44
7) Relationship diagram
This diagram clarifies the interrelations in a complex situation involving many
interrelated factors and serves to clarify the cause and effect relationships among
factors
Description
Relations diagram is defined as a technique used to solve problems that have complex
cause and effect relationships among a number of problems and factors that influence
them
Format
A special feature of relation diagram is its unrestricted Format However general
formats are as given below
1) Centrally converging relations diagram
The major item or problem to be solved is located in the center and the related factors
are arranged around the item or problem in such a way as to indicate close
relationships
2) Directionally intensive relations diagram
The major item or problem to be solved is located on one side of the diagram and the
various factors arranged in accordance with the flow of their major cause-and-effect
relationships on the other side
3) Relationship indication relations diagram
There are no restrictions on this format because the main point is to arrange the cause-
and-effect Relationships of the application items or factors so that they are expressed
in a straightforward manner in a Diagram
45
Procedure
1) Define the issueproblem in such a way that it is clearly understood and agreed on
by team members
2) Assemble the cross-functional team
3) Layout all the ideasissue cards that have been brought from other tools
4) Look for causeinfluence relationships between all ideas and draw relationship
arrows
a) Choose any of the ideas as a starting point and work through them in sequence
b)An outgoing arrow from an idea indicates that it is the stronger cause or influence
c) Draw only one way relationship arrows in the direction of the stronger cause or
Influence Make a decision on the stronger direction Do not draw two headed arrows
5) Review and revise the relationsrsquo diagram
6) Tally the number of outgoing and incoming arrows and select key items for further
planning
-record and clearly mark next to each issue the number of arrows going in and out of
it
-find the items with the highest number outgoing arrows and the items with the
highest number of incoming arrows
-a high number of outgoing arrows indicate that the item is a root cause and should be
tackle first
46
-a high number of incoming arrows indicate that the item is a key outcome and may
become a focus for planning either as a meaningful measure of overall success or as a
redefinition of the original issue under discussion
Example
47
48
Conclusions
Statististical QC is chiefly concerned in making sure that several procedures
and working arrangements are in place to provide for effective and efficient
statistical processes to minimize the risk of errors or weaknesses in
procedures or systems or in source material
Seven QC tools are most helpful in troubleshooting issues related to quality
All processes are affected by multiple factors and therefore statistical QC tools
can be applied to any process
The continuous use of these tools upgrades the personnel characteristics of the
people involved It enhances their ability to think generate ideas solve
problem and do proper planning
49
References asqorglearn-about-qualityseven-basic-quality-toolsoverviewhtml
httpsenwikipediaorgwikiSeven_Basic_Tools_of_Quality
wwwijergsorgfilesdocumentsAPPLICATION-45pd
httpssrcalionsciencecompdfQualityToolspdf
www3haorghkqehwiserdoc7bqtpdf
wwwmathmunca~variyathNew7QCToolspd
50
- 1 DEFINITION of Quality Control
- 3 Competitiveness
- 4 Customer Loyalty
- 5 Reputation
- 6 Compliance
- 7 Costs
- Benefits of Using Quality Control in Manufacturing
-
2) Tree diagram
Application
A tree diagram is used to show the interrelation between a topic and its component
elements
Description
A tree diagram systematically breaks down a topic into its component elements Ideas
generated by
Brainstorming and graphed or clustered with an affinity diagram can be converted
into a tree diagram
to show logical and sequential links This tool can be used in planning and problem
solving
Procedure
State the topic to be studied clearly
Define the major categories of the topic(brainstorm or use the header cards
from the affinity diagram)
Construct the diagram by placing the topic in a box on the left-hand side
Branch the major categories laterally to the right
For each major category define the component elements and sub-elements if
any
Laterally branch to the right the component elements and sub-elements for
each major category and
Review the diagram to ensure that there are no gaps in either sequence or
logic
29
30
3) Arrow diagram
Purpose To create a visual presentation of the steps of a process or tasks necessary to
complete a project with special emphasis on the time taken for these activities
Procedure
1 List all the tasks or activities needed to be accomplished before the process of the
project
2 Decide which steps are undertaken in series and which steps can be run in parallel
Arrange the
Activities in a proper sequence
3 Prepare lsquoEvent Nodesrsquo at the completion of steps and number them
4 Write the description of the step and decide the time required for completing each
step
5 Calculate the earliest time to reach an event node for the start of the process
7 Ager the time for all event nodes including the completion of the process or the
project is available one calculates the latest time by which an event node must be
reached
Application
The diagram is also useful in planning and scheduling steps in complicated processes
especially in planning and scheduling projects which involve a large number of
activities
Example
31
1 Identify the tasks Eg 123hellip15
2 Know the time each task needs
3 Determine which tasks can be run in parallel and in normal sequences
4 Draw the sequence diagram and find the critical path
5 Calculate the project duration
6 Calculate the earliest starting time (or the earliest finishing time of last task) and the
latest finishing time
of each task(the latest starting time for the following task)
7 Mark the time indication
32
33
4) Process Decision Program Chart (PDPC)
Def The process decision program chart (PDPC) method helps us select the best
processes to obtain optimum results by evaluating the progress of events and various
conceivable outcomes
Description
The process decision program chart (PDPC) method is used to define the solution
process when dealing with problems that have more than one possible outcome [t
anticipates the unexpected Outcomes at each stage and plans for it
PDPC has two following patterns
Pattern I ndash In this pattern process starts with initial condition lsquoArsquo and proceeds to the
desired final condition lsquoZrsquo in an organized manner
Pattern 11- In this pattern first the final conditionrsquosrsquo is set Then the process from lsquoZrsquo
to the initial point lsquoArsquo is developed with the inclusion of various alternatives from
many points of view
Procedure
Discuss the issues related to the project among a cross-functional team
Discuss which issues must be examined and identify those issues
Consider and note down all the anticipated results for the identified issues
Weigh the feasibility of each solution proposed and investigate alternate
solutions
Classify each issue according to its urgency number of operations required
likelihood of Occurrence and difficulty
Consider the anticipated results and alternative solutions related to issues that
must be addressed immediately and link the items with arrows to the desired
goal
34
Prioritize the different issues and consider them all together Information
related to one set of
Possibilities could influence another set Related items shall be linked with a
broken line
If the department that will handle a process involving several lines is
determined circle
the process and write the name of the department within
Set a target date for completion
Have regular meetings to check progress in terms of the original PDPC
35
36
37
38
5) Matrix diagram
Purpose1) Explore the existence and the extent of relations between individual items in 2 sets
of factors or features and characteristics and express them in a symbolic form that is
easy to understand
2) Mostly used to understand the relations between the customer expectations as
expressed by the customers and product characteristics as designed manufactured and
tested by the manufacturer
Procedures1 Determine 2 sets of factors for which the relations are needed to be established
2 Divide the features and characteristics into primary secondary and tertiary
characteristics
3 Place the features vertically on the leg side of the matrix and characteristics
horizontally on top of the matrix
4 Enter the importance of the features on the column ager that for the tertiary
features10485775 In the main body of the matrix use the symbols to represent the degree of
connections between the feature and characteristics
6 Choose and define relationship symbols Most commonly used symbols are as
given below
Strong relationship=
Relationship =
Likely relationship=
Application
bull Matrix diagram can be used to solve problems by arranging data in such a way that
the relations between relevant factors are brought into sharp focus
bull There is no limit to the use of the tool
39
bull The most important application of matrix diagram is in clarifying relations between
individual features of customer requirements and individual product characteristics
Example 1
Matrix Diagram for Quality Functions and Responsibilities
40
41
6) Matrix Data Analysis Diagram1048577
Purpose
To present numerical data about two sets of factors in a matrix form and
analyze it to get numerical output
Can be applied in understanding the products and products characteristics
Procedure1048577
1 Decide the two factors whose relations are to be analyzed
2 Check the number of individual items in the two factors
3 Prepare a matrix to accommodate all the items of the two factors
4 Enter numerical data in the matrix
5 Give the diagram a suitable title
Example
42
43
44
7) Relationship diagram
This diagram clarifies the interrelations in a complex situation involving many
interrelated factors and serves to clarify the cause and effect relationships among
factors
Description
Relations diagram is defined as a technique used to solve problems that have complex
cause and effect relationships among a number of problems and factors that influence
them
Format
A special feature of relation diagram is its unrestricted Format However general
formats are as given below
1) Centrally converging relations diagram
The major item or problem to be solved is located in the center and the related factors
are arranged around the item or problem in such a way as to indicate close
relationships
2) Directionally intensive relations diagram
The major item or problem to be solved is located on one side of the diagram and the
various factors arranged in accordance with the flow of their major cause-and-effect
relationships on the other side
3) Relationship indication relations diagram
There are no restrictions on this format because the main point is to arrange the cause-
and-effect Relationships of the application items or factors so that they are expressed
in a straightforward manner in a Diagram
45
Procedure
1) Define the issueproblem in such a way that it is clearly understood and agreed on
by team members
2) Assemble the cross-functional team
3) Layout all the ideasissue cards that have been brought from other tools
4) Look for causeinfluence relationships between all ideas and draw relationship
arrows
a) Choose any of the ideas as a starting point and work through them in sequence
b)An outgoing arrow from an idea indicates that it is the stronger cause or influence
c) Draw only one way relationship arrows in the direction of the stronger cause or
Influence Make a decision on the stronger direction Do not draw two headed arrows
5) Review and revise the relationsrsquo diagram
6) Tally the number of outgoing and incoming arrows and select key items for further
planning
-record and clearly mark next to each issue the number of arrows going in and out of
it
-find the items with the highest number outgoing arrows and the items with the
highest number of incoming arrows
-a high number of outgoing arrows indicate that the item is a root cause and should be
tackle first
46
-a high number of incoming arrows indicate that the item is a key outcome and may
become a focus for planning either as a meaningful measure of overall success or as a
redefinition of the original issue under discussion
Example
47
48
Conclusions
Statististical QC is chiefly concerned in making sure that several procedures
and working arrangements are in place to provide for effective and efficient
statistical processes to minimize the risk of errors or weaknesses in
procedures or systems or in source material
Seven QC tools are most helpful in troubleshooting issues related to quality
All processes are affected by multiple factors and therefore statistical QC tools
can be applied to any process
The continuous use of these tools upgrades the personnel characteristics of the
people involved It enhances their ability to think generate ideas solve
problem and do proper planning
49
References asqorglearn-about-qualityseven-basic-quality-toolsoverviewhtml
httpsenwikipediaorgwikiSeven_Basic_Tools_of_Quality
wwwijergsorgfilesdocumentsAPPLICATION-45pd
httpssrcalionsciencecompdfQualityToolspdf
www3haorghkqehwiserdoc7bqtpdf
wwwmathmunca~variyathNew7QCToolspd
50
- 1 DEFINITION of Quality Control
- 3 Competitiveness
- 4 Customer Loyalty
- 5 Reputation
- 6 Compliance
- 7 Costs
- Benefits of Using Quality Control in Manufacturing
-
30
3) Arrow diagram
Purpose To create a visual presentation of the steps of a process or tasks necessary to
complete a project with special emphasis on the time taken for these activities
Procedure
1 List all the tasks or activities needed to be accomplished before the process of the
project
2 Decide which steps are undertaken in series and which steps can be run in parallel
Arrange the
Activities in a proper sequence
3 Prepare lsquoEvent Nodesrsquo at the completion of steps and number them
4 Write the description of the step and decide the time required for completing each
step
5 Calculate the earliest time to reach an event node for the start of the process
7 Ager the time for all event nodes including the completion of the process or the
project is available one calculates the latest time by which an event node must be
reached
Application
The diagram is also useful in planning and scheduling steps in complicated processes
especially in planning and scheduling projects which involve a large number of
activities
Example
31
1 Identify the tasks Eg 123hellip15
2 Know the time each task needs
3 Determine which tasks can be run in parallel and in normal sequences
4 Draw the sequence diagram and find the critical path
5 Calculate the project duration
6 Calculate the earliest starting time (or the earliest finishing time of last task) and the
latest finishing time
of each task(the latest starting time for the following task)
7 Mark the time indication
32
33
4) Process Decision Program Chart (PDPC)
Def The process decision program chart (PDPC) method helps us select the best
processes to obtain optimum results by evaluating the progress of events and various
conceivable outcomes
Description
The process decision program chart (PDPC) method is used to define the solution
process when dealing with problems that have more than one possible outcome [t
anticipates the unexpected Outcomes at each stage and plans for it
PDPC has two following patterns
Pattern I ndash In this pattern process starts with initial condition lsquoArsquo and proceeds to the
desired final condition lsquoZrsquo in an organized manner
Pattern 11- In this pattern first the final conditionrsquosrsquo is set Then the process from lsquoZrsquo
to the initial point lsquoArsquo is developed with the inclusion of various alternatives from
many points of view
Procedure
Discuss the issues related to the project among a cross-functional team
Discuss which issues must be examined and identify those issues
Consider and note down all the anticipated results for the identified issues
Weigh the feasibility of each solution proposed and investigate alternate
solutions
Classify each issue according to its urgency number of operations required
likelihood of Occurrence and difficulty
Consider the anticipated results and alternative solutions related to issues that
must be addressed immediately and link the items with arrows to the desired
goal
34
Prioritize the different issues and consider them all together Information
related to one set of
Possibilities could influence another set Related items shall be linked with a
broken line
If the department that will handle a process involving several lines is
determined circle
the process and write the name of the department within
Set a target date for completion
Have regular meetings to check progress in terms of the original PDPC
35
36
37
38
5) Matrix diagram
Purpose1) Explore the existence and the extent of relations between individual items in 2 sets
of factors or features and characteristics and express them in a symbolic form that is
easy to understand
2) Mostly used to understand the relations between the customer expectations as
expressed by the customers and product characteristics as designed manufactured and
tested by the manufacturer
Procedures1 Determine 2 sets of factors for which the relations are needed to be established
2 Divide the features and characteristics into primary secondary and tertiary
characteristics
3 Place the features vertically on the leg side of the matrix and characteristics
horizontally on top of the matrix
4 Enter the importance of the features on the column ager that for the tertiary
features10485775 In the main body of the matrix use the symbols to represent the degree of
connections between the feature and characteristics
6 Choose and define relationship symbols Most commonly used symbols are as
given below
Strong relationship=
Relationship =
Likely relationship=
Application
bull Matrix diagram can be used to solve problems by arranging data in such a way that
the relations between relevant factors are brought into sharp focus
bull There is no limit to the use of the tool
39
bull The most important application of matrix diagram is in clarifying relations between
individual features of customer requirements and individual product characteristics
Example 1
Matrix Diagram for Quality Functions and Responsibilities
40
41
6) Matrix Data Analysis Diagram1048577
Purpose
To present numerical data about two sets of factors in a matrix form and
analyze it to get numerical output
Can be applied in understanding the products and products characteristics
Procedure1048577
1 Decide the two factors whose relations are to be analyzed
2 Check the number of individual items in the two factors
3 Prepare a matrix to accommodate all the items of the two factors
4 Enter numerical data in the matrix
5 Give the diagram a suitable title
Example
42
43
44
7) Relationship diagram
This diagram clarifies the interrelations in a complex situation involving many
interrelated factors and serves to clarify the cause and effect relationships among
factors
Description
Relations diagram is defined as a technique used to solve problems that have complex
cause and effect relationships among a number of problems and factors that influence
them
Format
A special feature of relation diagram is its unrestricted Format However general
formats are as given below
1) Centrally converging relations diagram
The major item or problem to be solved is located in the center and the related factors
are arranged around the item or problem in such a way as to indicate close
relationships
2) Directionally intensive relations diagram
The major item or problem to be solved is located on one side of the diagram and the
various factors arranged in accordance with the flow of their major cause-and-effect
relationships on the other side
3) Relationship indication relations diagram
There are no restrictions on this format because the main point is to arrange the cause-
and-effect Relationships of the application items or factors so that they are expressed
in a straightforward manner in a Diagram
45
Procedure
1) Define the issueproblem in such a way that it is clearly understood and agreed on
by team members
2) Assemble the cross-functional team
3) Layout all the ideasissue cards that have been brought from other tools
4) Look for causeinfluence relationships between all ideas and draw relationship
arrows
a) Choose any of the ideas as a starting point and work through them in sequence
b)An outgoing arrow from an idea indicates that it is the stronger cause or influence
c) Draw only one way relationship arrows in the direction of the stronger cause or
Influence Make a decision on the stronger direction Do not draw two headed arrows
5) Review and revise the relationsrsquo diagram
6) Tally the number of outgoing and incoming arrows and select key items for further
planning
-record and clearly mark next to each issue the number of arrows going in and out of
it
-find the items with the highest number outgoing arrows and the items with the
highest number of incoming arrows
-a high number of outgoing arrows indicate that the item is a root cause and should be
tackle first
46
-a high number of incoming arrows indicate that the item is a key outcome and may
become a focus for planning either as a meaningful measure of overall success or as a
redefinition of the original issue under discussion
Example
47
48
Conclusions
Statististical QC is chiefly concerned in making sure that several procedures
and working arrangements are in place to provide for effective and efficient
statistical processes to minimize the risk of errors or weaknesses in
procedures or systems or in source material
Seven QC tools are most helpful in troubleshooting issues related to quality
All processes are affected by multiple factors and therefore statistical QC tools
can be applied to any process
The continuous use of these tools upgrades the personnel characteristics of the
people involved It enhances their ability to think generate ideas solve
problem and do proper planning
49
References asqorglearn-about-qualityseven-basic-quality-toolsoverviewhtml
httpsenwikipediaorgwikiSeven_Basic_Tools_of_Quality
wwwijergsorgfilesdocumentsAPPLICATION-45pd
httpssrcalionsciencecompdfQualityToolspdf
www3haorghkqehwiserdoc7bqtpdf
wwwmathmunca~variyathNew7QCToolspd
50
- 1 DEFINITION of Quality Control
- 3 Competitiveness
- 4 Customer Loyalty
- 5 Reputation
- 6 Compliance
- 7 Costs
- Benefits of Using Quality Control in Manufacturing
-
3) Arrow diagram
Purpose To create a visual presentation of the steps of a process or tasks necessary to
complete a project with special emphasis on the time taken for these activities
Procedure
1 List all the tasks or activities needed to be accomplished before the process of the
project
2 Decide which steps are undertaken in series and which steps can be run in parallel
Arrange the
Activities in a proper sequence
3 Prepare lsquoEvent Nodesrsquo at the completion of steps and number them
4 Write the description of the step and decide the time required for completing each
step
5 Calculate the earliest time to reach an event node for the start of the process
7 Ager the time for all event nodes including the completion of the process or the
project is available one calculates the latest time by which an event node must be
reached
Application
The diagram is also useful in planning and scheduling steps in complicated processes
especially in planning and scheduling projects which involve a large number of
activities
Example
31
1 Identify the tasks Eg 123hellip15
2 Know the time each task needs
3 Determine which tasks can be run in parallel and in normal sequences
4 Draw the sequence diagram and find the critical path
5 Calculate the project duration
6 Calculate the earliest starting time (or the earliest finishing time of last task) and the
latest finishing time
of each task(the latest starting time for the following task)
7 Mark the time indication
32
33
4) Process Decision Program Chart (PDPC)
Def The process decision program chart (PDPC) method helps us select the best
processes to obtain optimum results by evaluating the progress of events and various
conceivable outcomes
Description
The process decision program chart (PDPC) method is used to define the solution
process when dealing with problems that have more than one possible outcome [t
anticipates the unexpected Outcomes at each stage and plans for it
PDPC has two following patterns
Pattern I ndash In this pattern process starts with initial condition lsquoArsquo and proceeds to the
desired final condition lsquoZrsquo in an organized manner
Pattern 11- In this pattern first the final conditionrsquosrsquo is set Then the process from lsquoZrsquo
to the initial point lsquoArsquo is developed with the inclusion of various alternatives from
many points of view
Procedure
Discuss the issues related to the project among a cross-functional team
Discuss which issues must be examined and identify those issues
Consider and note down all the anticipated results for the identified issues
Weigh the feasibility of each solution proposed and investigate alternate
solutions
Classify each issue according to its urgency number of operations required
likelihood of Occurrence and difficulty
Consider the anticipated results and alternative solutions related to issues that
must be addressed immediately and link the items with arrows to the desired
goal
34
Prioritize the different issues and consider them all together Information
related to one set of
Possibilities could influence another set Related items shall be linked with a
broken line
If the department that will handle a process involving several lines is
determined circle
the process and write the name of the department within
Set a target date for completion
Have regular meetings to check progress in terms of the original PDPC
35
36
37
38
5) Matrix diagram
Purpose1) Explore the existence and the extent of relations between individual items in 2 sets
of factors or features and characteristics and express them in a symbolic form that is
easy to understand
2) Mostly used to understand the relations between the customer expectations as
expressed by the customers and product characteristics as designed manufactured and
tested by the manufacturer
Procedures1 Determine 2 sets of factors for which the relations are needed to be established
2 Divide the features and characteristics into primary secondary and tertiary
characteristics
3 Place the features vertically on the leg side of the matrix and characteristics
horizontally on top of the matrix
4 Enter the importance of the features on the column ager that for the tertiary
features10485775 In the main body of the matrix use the symbols to represent the degree of
connections between the feature and characteristics
6 Choose and define relationship symbols Most commonly used symbols are as
given below
Strong relationship=
Relationship =
Likely relationship=
Application
bull Matrix diagram can be used to solve problems by arranging data in such a way that
the relations between relevant factors are brought into sharp focus
bull There is no limit to the use of the tool
39
bull The most important application of matrix diagram is in clarifying relations between
individual features of customer requirements and individual product characteristics
Example 1
Matrix Diagram for Quality Functions and Responsibilities
40
41
6) Matrix Data Analysis Diagram1048577
Purpose
To present numerical data about two sets of factors in a matrix form and
analyze it to get numerical output
Can be applied in understanding the products and products characteristics
Procedure1048577
1 Decide the two factors whose relations are to be analyzed
2 Check the number of individual items in the two factors
3 Prepare a matrix to accommodate all the items of the two factors
4 Enter numerical data in the matrix
5 Give the diagram a suitable title
Example
42
43
44
7) Relationship diagram
This diagram clarifies the interrelations in a complex situation involving many
interrelated factors and serves to clarify the cause and effect relationships among
factors
Description
Relations diagram is defined as a technique used to solve problems that have complex
cause and effect relationships among a number of problems and factors that influence
them
Format
A special feature of relation diagram is its unrestricted Format However general
formats are as given below
1) Centrally converging relations diagram
The major item or problem to be solved is located in the center and the related factors
are arranged around the item or problem in such a way as to indicate close
relationships
2) Directionally intensive relations diagram
The major item or problem to be solved is located on one side of the diagram and the
various factors arranged in accordance with the flow of their major cause-and-effect
relationships on the other side
3) Relationship indication relations diagram
There are no restrictions on this format because the main point is to arrange the cause-
and-effect Relationships of the application items or factors so that they are expressed
in a straightforward manner in a Diagram
45
Procedure
1) Define the issueproblem in such a way that it is clearly understood and agreed on
by team members
2) Assemble the cross-functional team
3) Layout all the ideasissue cards that have been brought from other tools
4) Look for causeinfluence relationships between all ideas and draw relationship
arrows
a) Choose any of the ideas as a starting point and work through them in sequence
b)An outgoing arrow from an idea indicates that it is the stronger cause or influence
c) Draw only one way relationship arrows in the direction of the stronger cause or
Influence Make a decision on the stronger direction Do not draw two headed arrows
5) Review and revise the relationsrsquo diagram
6) Tally the number of outgoing and incoming arrows and select key items for further
planning
-record and clearly mark next to each issue the number of arrows going in and out of
it
-find the items with the highest number outgoing arrows and the items with the
highest number of incoming arrows
-a high number of outgoing arrows indicate that the item is a root cause and should be
tackle first
46
-a high number of incoming arrows indicate that the item is a key outcome and may
become a focus for planning either as a meaningful measure of overall success or as a
redefinition of the original issue under discussion
Example
47
48
Conclusions
Statististical QC is chiefly concerned in making sure that several procedures
and working arrangements are in place to provide for effective and efficient
statistical processes to minimize the risk of errors or weaknesses in
procedures or systems or in source material
Seven QC tools are most helpful in troubleshooting issues related to quality
All processes are affected by multiple factors and therefore statistical QC tools
can be applied to any process
The continuous use of these tools upgrades the personnel characteristics of the
people involved It enhances their ability to think generate ideas solve
problem and do proper planning
49
References asqorglearn-about-qualityseven-basic-quality-toolsoverviewhtml
httpsenwikipediaorgwikiSeven_Basic_Tools_of_Quality
wwwijergsorgfilesdocumentsAPPLICATION-45pd
httpssrcalionsciencecompdfQualityToolspdf
www3haorghkqehwiserdoc7bqtpdf
wwwmathmunca~variyathNew7QCToolspd
50
- 1 DEFINITION of Quality Control
- 3 Competitiveness
- 4 Customer Loyalty
- 5 Reputation
- 6 Compliance
- 7 Costs
- Benefits of Using Quality Control in Manufacturing
-
1 Identify the tasks Eg 123hellip15
2 Know the time each task needs
3 Determine which tasks can be run in parallel and in normal sequences
4 Draw the sequence diagram and find the critical path
5 Calculate the project duration
6 Calculate the earliest starting time (or the earliest finishing time of last task) and the
latest finishing time
of each task(the latest starting time for the following task)
7 Mark the time indication
32
33
4) Process Decision Program Chart (PDPC)
Def The process decision program chart (PDPC) method helps us select the best
processes to obtain optimum results by evaluating the progress of events and various
conceivable outcomes
Description
The process decision program chart (PDPC) method is used to define the solution
process when dealing with problems that have more than one possible outcome [t
anticipates the unexpected Outcomes at each stage and plans for it
PDPC has two following patterns
Pattern I ndash In this pattern process starts with initial condition lsquoArsquo and proceeds to the
desired final condition lsquoZrsquo in an organized manner
Pattern 11- In this pattern first the final conditionrsquosrsquo is set Then the process from lsquoZrsquo
to the initial point lsquoArsquo is developed with the inclusion of various alternatives from
many points of view
Procedure
Discuss the issues related to the project among a cross-functional team
Discuss which issues must be examined and identify those issues
Consider and note down all the anticipated results for the identified issues
Weigh the feasibility of each solution proposed and investigate alternate
solutions
Classify each issue according to its urgency number of operations required
likelihood of Occurrence and difficulty
Consider the anticipated results and alternative solutions related to issues that
must be addressed immediately and link the items with arrows to the desired
goal
34
Prioritize the different issues and consider them all together Information
related to one set of
Possibilities could influence another set Related items shall be linked with a
broken line
If the department that will handle a process involving several lines is
determined circle
the process and write the name of the department within
Set a target date for completion
Have regular meetings to check progress in terms of the original PDPC
35
36
37
38
5) Matrix diagram
Purpose1) Explore the existence and the extent of relations between individual items in 2 sets
of factors or features and characteristics and express them in a symbolic form that is
easy to understand
2) Mostly used to understand the relations between the customer expectations as
expressed by the customers and product characteristics as designed manufactured and
tested by the manufacturer
Procedures1 Determine 2 sets of factors for which the relations are needed to be established
2 Divide the features and characteristics into primary secondary and tertiary
characteristics
3 Place the features vertically on the leg side of the matrix and characteristics
horizontally on top of the matrix
4 Enter the importance of the features on the column ager that for the tertiary
features10485775 In the main body of the matrix use the symbols to represent the degree of
connections between the feature and characteristics
6 Choose and define relationship symbols Most commonly used symbols are as
given below
Strong relationship=
Relationship =
Likely relationship=
Application
bull Matrix diagram can be used to solve problems by arranging data in such a way that
the relations between relevant factors are brought into sharp focus
bull There is no limit to the use of the tool
39
bull The most important application of matrix diagram is in clarifying relations between
individual features of customer requirements and individual product characteristics
Example 1
Matrix Diagram for Quality Functions and Responsibilities
40
41
6) Matrix Data Analysis Diagram1048577
Purpose
To present numerical data about two sets of factors in a matrix form and
analyze it to get numerical output
Can be applied in understanding the products and products characteristics
Procedure1048577
1 Decide the two factors whose relations are to be analyzed
2 Check the number of individual items in the two factors
3 Prepare a matrix to accommodate all the items of the two factors
4 Enter numerical data in the matrix
5 Give the diagram a suitable title
Example
42
43
44
7) Relationship diagram
This diagram clarifies the interrelations in a complex situation involving many
interrelated factors and serves to clarify the cause and effect relationships among
factors
Description
Relations diagram is defined as a technique used to solve problems that have complex
cause and effect relationships among a number of problems and factors that influence
them
Format
A special feature of relation diagram is its unrestricted Format However general
formats are as given below
1) Centrally converging relations diagram
The major item or problem to be solved is located in the center and the related factors
are arranged around the item or problem in such a way as to indicate close
relationships
2) Directionally intensive relations diagram
The major item or problem to be solved is located on one side of the diagram and the
various factors arranged in accordance with the flow of their major cause-and-effect
relationships on the other side
3) Relationship indication relations diagram
There are no restrictions on this format because the main point is to arrange the cause-
and-effect Relationships of the application items or factors so that they are expressed
in a straightforward manner in a Diagram
45
Procedure
1) Define the issueproblem in such a way that it is clearly understood and agreed on
by team members
2) Assemble the cross-functional team
3) Layout all the ideasissue cards that have been brought from other tools
4) Look for causeinfluence relationships between all ideas and draw relationship
arrows
a) Choose any of the ideas as a starting point and work through them in sequence
b)An outgoing arrow from an idea indicates that it is the stronger cause or influence
c) Draw only one way relationship arrows in the direction of the stronger cause or
Influence Make a decision on the stronger direction Do not draw two headed arrows
5) Review and revise the relationsrsquo diagram
6) Tally the number of outgoing and incoming arrows and select key items for further
planning
-record and clearly mark next to each issue the number of arrows going in and out of
it
-find the items with the highest number outgoing arrows and the items with the
highest number of incoming arrows
-a high number of outgoing arrows indicate that the item is a root cause and should be
tackle first
46
-a high number of incoming arrows indicate that the item is a key outcome and may
become a focus for planning either as a meaningful measure of overall success or as a
redefinition of the original issue under discussion
Example
47
48
Conclusions
Statististical QC is chiefly concerned in making sure that several procedures
and working arrangements are in place to provide for effective and efficient
statistical processes to minimize the risk of errors or weaknesses in
procedures or systems or in source material
Seven QC tools are most helpful in troubleshooting issues related to quality
All processes are affected by multiple factors and therefore statistical QC tools
can be applied to any process
The continuous use of these tools upgrades the personnel characteristics of the
people involved It enhances their ability to think generate ideas solve
problem and do proper planning
49
References asqorglearn-about-qualityseven-basic-quality-toolsoverviewhtml
httpsenwikipediaorgwikiSeven_Basic_Tools_of_Quality
wwwijergsorgfilesdocumentsAPPLICATION-45pd
httpssrcalionsciencecompdfQualityToolspdf
www3haorghkqehwiserdoc7bqtpdf
wwwmathmunca~variyathNew7QCToolspd
50
- 1 DEFINITION of Quality Control
- 3 Competitiveness
- 4 Customer Loyalty
- 5 Reputation
- 6 Compliance
- 7 Costs
- Benefits of Using Quality Control in Manufacturing
-
33
4) Process Decision Program Chart (PDPC)
Def The process decision program chart (PDPC) method helps us select the best
processes to obtain optimum results by evaluating the progress of events and various
conceivable outcomes
Description
The process decision program chart (PDPC) method is used to define the solution
process when dealing with problems that have more than one possible outcome [t
anticipates the unexpected Outcomes at each stage and plans for it
PDPC has two following patterns
Pattern I ndash In this pattern process starts with initial condition lsquoArsquo and proceeds to the
desired final condition lsquoZrsquo in an organized manner
Pattern 11- In this pattern first the final conditionrsquosrsquo is set Then the process from lsquoZrsquo
to the initial point lsquoArsquo is developed with the inclusion of various alternatives from
many points of view
Procedure
Discuss the issues related to the project among a cross-functional team
Discuss which issues must be examined and identify those issues
Consider and note down all the anticipated results for the identified issues
Weigh the feasibility of each solution proposed and investigate alternate
solutions
Classify each issue according to its urgency number of operations required
likelihood of Occurrence and difficulty
Consider the anticipated results and alternative solutions related to issues that
must be addressed immediately and link the items with arrows to the desired
goal
34
Prioritize the different issues and consider them all together Information
related to one set of
Possibilities could influence another set Related items shall be linked with a
broken line
If the department that will handle a process involving several lines is
determined circle
the process and write the name of the department within
Set a target date for completion
Have regular meetings to check progress in terms of the original PDPC
35
36
37
38
5) Matrix diagram
Purpose1) Explore the existence and the extent of relations between individual items in 2 sets
of factors or features and characteristics and express them in a symbolic form that is
easy to understand
2) Mostly used to understand the relations between the customer expectations as
expressed by the customers and product characteristics as designed manufactured and
tested by the manufacturer
Procedures1 Determine 2 sets of factors for which the relations are needed to be established
2 Divide the features and characteristics into primary secondary and tertiary
characteristics
3 Place the features vertically on the leg side of the matrix and characteristics
horizontally on top of the matrix
4 Enter the importance of the features on the column ager that for the tertiary
features10485775 In the main body of the matrix use the symbols to represent the degree of
connections between the feature and characteristics
6 Choose and define relationship symbols Most commonly used symbols are as
given below
Strong relationship=
Relationship =
Likely relationship=
Application
bull Matrix diagram can be used to solve problems by arranging data in such a way that
the relations between relevant factors are brought into sharp focus
bull There is no limit to the use of the tool
39
bull The most important application of matrix diagram is in clarifying relations between
individual features of customer requirements and individual product characteristics
Example 1
Matrix Diagram for Quality Functions and Responsibilities
40
41
6) Matrix Data Analysis Diagram1048577
Purpose
To present numerical data about two sets of factors in a matrix form and
analyze it to get numerical output
Can be applied in understanding the products and products characteristics
Procedure1048577
1 Decide the two factors whose relations are to be analyzed
2 Check the number of individual items in the two factors
3 Prepare a matrix to accommodate all the items of the two factors
4 Enter numerical data in the matrix
5 Give the diagram a suitable title
Example
42
43
44
7) Relationship diagram
This diagram clarifies the interrelations in a complex situation involving many
interrelated factors and serves to clarify the cause and effect relationships among
factors
Description
Relations diagram is defined as a technique used to solve problems that have complex
cause and effect relationships among a number of problems and factors that influence
them
Format
A special feature of relation diagram is its unrestricted Format However general
formats are as given below
1) Centrally converging relations diagram
The major item or problem to be solved is located in the center and the related factors
are arranged around the item or problem in such a way as to indicate close
relationships
2) Directionally intensive relations diagram
The major item or problem to be solved is located on one side of the diagram and the
various factors arranged in accordance with the flow of their major cause-and-effect
relationships on the other side
3) Relationship indication relations diagram
There are no restrictions on this format because the main point is to arrange the cause-
and-effect Relationships of the application items or factors so that they are expressed
in a straightforward manner in a Diagram
45
Procedure
1) Define the issueproblem in such a way that it is clearly understood and agreed on
by team members
2) Assemble the cross-functional team
3) Layout all the ideasissue cards that have been brought from other tools
4) Look for causeinfluence relationships between all ideas and draw relationship
arrows
a) Choose any of the ideas as a starting point and work through them in sequence
b)An outgoing arrow from an idea indicates that it is the stronger cause or influence
c) Draw only one way relationship arrows in the direction of the stronger cause or
Influence Make a decision on the stronger direction Do not draw two headed arrows
5) Review and revise the relationsrsquo diagram
6) Tally the number of outgoing and incoming arrows and select key items for further
planning
-record and clearly mark next to each issue the number of arrows going in and out of
it
-find the items with the highest number outgoing arrows and the items with the
highest number of incoming arrows
-a high number of outgoing arrows indicate that the item is a root cause and should be
tackle first
46
-a high number of incoming arrows indicate that the item is a key outcome and may
become a focus for planning either as a meaningful measure of overall success or as a
redefinition of the original issue under discussion
Example
47
48
Conclusions
Statististical QC is chiefly concerned in making sure that several procedures
and working arrangements are in place to provide for effective and efficient
statistical processes to minimize the risk of errors or weaknesses in
procedures or systems or in source material
Seven QC tools are most helpful in troubleshooting issues related to quality
All processes are affected by multiple factors and therefore statistical QC tools
can be applied to any process
The continuous use of these tools upgrades the personnel characteristics of the
people involved It enhances their ability to think generate ideas solve
problem and do proper planning
49
References asqorglearn-about-qualityseven-basic-quality-toolsoverviewhtml
httpsenwikipediaorgwikiSeven_Basic_Tools_of_Quality
wwwijergsorgfilesdocumentsAPPLICATION-45pd
httpssrcalionsciencecompdfQualityToolspdf
www3haorghkqehwiserdoc7bqtpdf
wwwmathmunca~variyathNew7QCToolspd
50
- 1 DEFINITION of Quality Control
- 3 Competitiveness
- 4 Customer Loyalty
- 5 Reputation
- 6 Compliance
- 7 Costs
- Benefits of Using Quality Control in Manufacturing
-
4) Process Decision Program Chart (PDPC)
Def The process decision program chart (PDPC) method helps us select the best
processes to obtain optimum results by evaluating the progress of events and various
conceivable outcomes
Description
The process decision program chart (PDPC) method is used to define the solution
process when dealing with problems that have more than one possible outcome [t
anticipates the unexpected Outcomes at each stage and plans for it
PDPC has two following patterns
Pattern I ndash In this pattern process starts with initial condition lsquoArsquo and proceeds to the
desired final condition lsquoZrsquo in an organized manner
Pattern 11- In this pattern first the final conditionrsquosrsquo is set Then the process from lsquoZrsquo
to the initial point lsquoArsquo is developed with the inclusion of various alternatives from
many points of view
Procedure
Discuss the issues related to the project among a cross-functional team
Discuss which issues must be examined and identify those issues
Consider and note down all the anticipated results for the identified issues
Weigh the feasibility of each solution proposed and investigate alternate
solutions
Classify each issue according to its urgency number of operations required
likelihood of Occurrence and difficulty
Consider the anticipated results and alternative solutions related to issues that
must be addressed immediately and link the items with arrows to the desired
goal
34
Prioritize the different issues and consider them all together Information
related to one set of
Possibilities could influence another set Related items shall be linked with a
broken line
If the department that will handle a process involving several lines is
determined circle
the process and write the name of the department within
Set a target date for completion
Have regular meetings to check progress in terms of the original PDPC
35
36
37
38
5) Matrix diagram
Purpose1) Explore the existence and the extent of relations between individual items in 2 sets
of factors or features and characteristics and express them in a symbolic form that is
easy to understand
2) Mostly used to understand the relations between the customer expectations as
expressed by the customers and product characteristics as designed manufactured and
tested by the manufacturer
Procedures1 Determine 2 sets of factors for which the relations are needed to be established
2 Divide the features and characteristics into primary secondary and tertiary
characteristics
3 Place the features vertically on the leg side of the matrix and characteristics
horizontally on top of the matrix
4 Enter the importance of the features on the column ager that for the tertiary
features10485775 In the main body of the matrix use the symbols to represent the degree of
connections between the feature and characteristics
6 Choose and define relationship symbols Most commonly used symbols are as
given below
Strong relationship=
Relationship =
Likely relationship=
Application
bull Matrix diagram can be used to solve problems by arranging data in such a way that
the relations between relevant factors are brought into sharp focus
bull There is no limit to the use of the tool
39
bull The most important application of matrix diagram is in clarifying relations between
individual features of customer requirements and individual product characteristics
Example 1
Matrix Diagram for Quality Functions and Responsibilities
40
41
6) Matrix Data Analysis Diagram1048577
Purpose
To present numerical data about two sets of factors in a matrix form and
analyze it to get numerical output
Can be applied in understanding the products and products characteristics
Procedure1048577
1 Decide the two factors whose relations are to be analyzed
2 Check the number of individual items in the two factors
3 Prepare a matrix to accommodate all the items of the two factors
4 Enter numerical data in the matrix
5 Give the diagram a suitable title
Example
42
43
44
7) Relationship diagram
This diagram clarifies the interrelations in a complex situation involving many
interrelated factors and serves to clarify the cause and effect relationships among
factors
Description
Relations diagram is defined as a technique used to solve problems that have complex
cause and effect relationships among a number of problems and factors that influence
them
Format
A special feature of relation diagram is its unrestricted Format However general
formats are as given below
1) Centrally converging relations diagram
The major item or problem to be solved is located in the center and the related factors
are arranged around the item or problem in such a way as to indicate close
relationships
2) Directionally intensive relations diagram
The major item or problem to be solved is located on one side of the diagram and the
various factors arranged in accordance with the flow of their major cause-and-effect
relationships on the other side
3) Relationship indication relations diagram
There are no restrictions on this format because the main point is to arrange the cause-
and-effect Relationships of the application items or factors so that they are expressed
in a straightforward manner in a Diagram
45
Procedure
1) Define the issueproblem in such a way that it is clearly understood and agreed on
by team members
2) Assemble the cross-functional team
3) Layout all the ideasissue cards that have been brought from other tools
4) Look for causeinfluence relationships between all ideas and draw relationship
arrows
a) Choose any of the ideas as a starting point and work through them in sequence
b)An outgoing arrow from an idea indicates that it is the stronger cause or influence
c) Draw only one way relationship arrows in the direction of the stronger cause or
Influence Make a decision on the stronger direction Do not draw two headed arrows
5) Review and revise the relationsrsquo diagram
6) Tally the number of outgoing and incoming arrows and select key items for further
planning
-record and clearly mark next to each issue the number of arrows going in and out of
it
-find the items with the highest number outgoing arrows and the items with the
highest number of incoming arrows
-a high number of outgoing arrows indicate that the item is a root cause and should be
tackle first
46
-a high number of incoming arrows indicate that the item is a key outcome and may
become a focus for planning either as a meaningful measure of overall success or as a
redefinition of the original issue under discussion
Example
47
48
Conclusions
Statististical QC is chiefly concerned in making sure that several procedures
and working arrangements are in place to provide for effective and efficient
statistical processes to minimize the risk of errors or weaknesses in
procedures or systems or in source material
Seven QC tools are most helpful in troubleshooting issues related to quality
All processes are affected by multiple factors and therefore statistical QC tools
can be applied to any process
The continuous use of these tools upgrades the personnel characteristics of the
people involved It enhances their ability to think generate ideas solve
problem and do proper planning
49
References asqorglearn-about-qualityseven-basic-quality-toolsoverviewhtml
httpsenwikipediaorgwikiSeven_Basic_Tools_of_Quality
wwwijergsorgfilesdocumentsAPPLICATION-45pd
httpssrcalionsciencecompdfQualityToolspdf
www3haorghkqehwiserdoc7bqtpdf
wwwmathmunca~variyathNew7QCToolspd
50
- 1 DEFINITION of Quality Control
- 3 Competitiveness
- 4 Customer Loyalty
- 5 Reputation
- 6 Compliance
- 7 Costs
- Benefits of Using Quality Control in Manufacturing
-
Prioritize the different issues and consider them all together Information
related to one set of
Possibilities could influence another set Related items shall be linked with a
broken line
If the department that will handle a process involving several lines is
determined circle
the process and write the name of the department within
Set a target date for completion
Have regular meetings to check progress in terms of the original PDPC
35
36
37
38
5) Matrix diagram
Purpose1) Explore the existence and the extent of relations between individual items in 2 sets
of factors or features and characteristics and express them in a symbolic form that is
easy to understand
2) Mostly used to understand the relations between the customer expectations as
expressed by the customers and product characteristics as designed manufactured and
tested by the manufacturer
Procedures1 Determine 2 sets of factors for which the relations are needed to be established
2 Divide the features and characteristics into primary secondary and tertiary
characteristics
3 Place the features vertically on the leg side of the matrix and characteristics
horizontally on top of the matrix
4 Enter the importance of the features on the column ager that for the tertiary
features10485775 In the main body of the matrix use the symbols to represent the degree of
connections between the feature and characteristics
6 Choose and define relationship symbols Most commonly used symbols are as
given below
Strong relationship=
Relationship =
Likely relationship=
Application
bull Matrix diagram can be used to solve problems by arranging data in such a way that
the relations between relevant factors are brought into sharp focus
bull There is no limit to the use of the tool
39
bull The most important application of matrix diagram is in clarifying relations between
individual features of customer requirements and individual product characteristics
Example 1
Matrix Diagram for Quality Functions and Responsibilities
40
41
6) Matrix Data Analysis Diagram1048577
Purpose
To present numerical data about two sets of factors in a matrix form and
analyze it to get numerical output
Can be applied in understanding the products and products characteristics
Procedure1048577
1 Decide the two factors whose relations are to be analyzed
2 Check the number of individual items in the two factors
3 Prepare a matrix to accommodate all the items of the two factors
4 Enter numerical data in the matrix
5 Give the diagram a suitable title
Example
42
43
44
7) Relationship diagram
This diagram clarifies the interrelations in a complex situation involving many
interrelated factors and serves to clarify the cause and effect relationships among
factors
Description
Relations diagram is defined as a technique used to solve problems that have complex
cause and effect relationships among a number of problems and factors that influence
them
Format
A special feature of relation diagram is its unrestricted Format However general
formats are as given below
1) Centrally converging relations diagram
The major item or problem to be solved is located in the center and the related factors
are arranged around the item or problem in such a way as to indicate close
relationships
2) Directionally intensive relations diagram
The major item or problem to be solved is located on one side of the diagram and the
various factors arranged in accordance with the flow of their major cause-and-effect
relationships on the other side
3) Relationship indication relations diagram
There are no restrictions on this format because the main point is to arrange the cause-
and-effect Relationships of the application items or factors so that they are expressed
in a straightforward manner in a Diagram
45
Procedure
1) Define the issueproblem in such a way that it is clearly understood and agreed on
by team members
2) Assemble the cross-functional team
3) Layout all the ideasissue cards that have been brought from other tools
4) Look for causeinfluence relationships between all ideas and draw relationship
arrows
a) Choose any of the ideas as a starting point and work through them in sequence
b)An outgoing arrow from an idea indicates that it is the stronger cause or influence
c) Draw only one way relationship arrows in the direction of the stronger cause or
Influence Make a decision on the stronger direction Do not draw two headed arrows
5) Review and revise the relationsrsquo diagram
6) Tally the number of outgoing and incoming arrows and select key items for further
planning
-record and clearly mark next to each issue the number of arrows going in and out of
it
-find the items with the highest number outgoing arrows and the items with the
highest number of incoming arrows
-a high number of outgoing arrows indicate that the item is a root cause and should be
tackle first
46
-a high number of incoming arrows indicate that the item is a key outcome and may
become a focus for planning either as a meaningful measure of overall success or as a
redefinition of the original issue under discussion
Example
47
48
Conclusions
Statististical QC is chiefly concerned in making sure that several procedures
and working arrangements are in place to provide for effective and efficient
statistical processes to minimize the risk of errors or weaknesses in
procedures or systems or in source material
Seven QC tools are most helpful in troubleshooting issues related to quality
All processes are affected by multiple factors and therefore statistical QC tools
can be applied to any process
The continuous use of these tools upgrades the personnel characteristics of the
people involved It enhances their ability to think generate ideas solve
problem and do proper planning
49
References asqorglearn-about-qualityseven-basic-quality-toolsoverviewhtml
httpsenwikipediaorgwikiSeven_Basic_Tools_of_Quality
wwwijergsorgfilesdocumentsAPPLICATION-45pd
httpssrcalionsciencecompdfQualityToolspdf
www3haorghkqehwiserdoc7bqtpdf
wwwmathmunca~variyathNew7QCToolspd
50
- 1 DEFINITION of Quality Control
- 3 Competitiveness
- 4 Customer Loyalty
- 5 Reputation
- 6 Compliance
- 7 Costs
- Benefits of Using Quality Control in Manufacturing
-
36
37
38
5) Matrix diagram
Purpose1) Explore the existence and the extent of relations between individual items in 2 sets
of factors or features and characteristics and express them in a symbolic form that is
easy to understand
2) Mostly used to understand the relations between the customer expectations as
expressed by the customers and product characteristics as designed manufactured and
tested by the manufacturer
Procedures1 Determine 2 sets of factors for which the relations are needed to be established
2 Divide the features and characteristics into primary secondary and tertiary
characteristics
3 Place the features vertically on the leg side of the matrix and characteristics
horizontally on top of the matrix
4 Enter the importance of the features on the column ager that for the tertiary
features10485775 In the main body of the matrix use the symbols to represent the degree of
connections between the feature and characteristics
6 Choose and define relationship symbols Most commonly used symbols are as
given below
Strong relationship=
Relationship =
Likely relationship=
Application
bull Matrix diagram can be used to solve problems by arranging data in such a way that
the relations between relevant factors are brought into sharp focus
bull There is no limit to the use of the tool
39
bull The most important application of matrix diagram is in clarifying relations between
individual features of customer requirements and individual product characteristics
Example 1
Matrix Diagram for Quality Functions and Responsibilities
40
41
6) Matrix Data Analysis Diagram1048577
Purpose
To present numerical data about two sets of factors in a matrix form and
analyze it to get numerical output
Can be applied in understanding the products and products characteristics
Procedure1048577
1 Decide the two factors whose relations are to be analyzed
2 Check the number of individual items in the two factors
3 Prepare a matrix to accommodate all the items of the two factors
4 Enter numerical data in the matrix
5 Give the diagram a suitable title
Example
42
43
44
7) Relationship diagram
This diagram clarifies the interrelations in a complex situation involving many
interrelated factors and serves to clarify the cause and effect relationships among
factors
Description
Relations diagram is defined as a technique used to solve problems that have complex
cause and effect relationships among a number of problems and factors that influence
them
Format
A special feature of relation diagram is its unrestricted Format However general
formats are as given below
1) Centrally converging relations diagram
The major item or problem to be solved is located in the center and the related factors
are arranged around the item or problem in such a way as to indicate close
relationships
2) Directionally intensive relations diagram
The major item or problem to be solved is located on one side of the diagram and the
various factors arranged in accordance with the flow of their major cause-and-effect
relationships on the other side
3) Relationship indication relations diagram
There are no restrictions on this format because the main point is to arrange the cause-
and-effect Relationships of the application items or factors so that they are expressed
in a straightforward manner in a Diagram
45
Procedure
1) Define the issueproblem in such a way that it is clearly understood and agreed on
by team members
2) Assemble the cross-functional team
3) Layout all the ideasissue cards that have been brought from other tools
4) Look for causeinfluence relationships between all ideas and draw relationship
arrows
a) Choose any of the ideas as a starting point and work through them in sequence
b)An outgoing arrow from an idea indicates that it is the stronger cause or influence
c) Draw only one way relationship arrows in the direction of the stronger cause or
Influence Make a decision on the stronger direction Do not draw two headed arrows
5) Review and revise the relationsrsquo diagram
6) Tally the number of outgoing and incoming arrows and select key items for further
planning
-record and clearly mark next to each issue the number of arrows going in and out of
it
-find the items with the highest number outgoing arrows and the items with the
highest number of incoming arrows
-a high number of outgoing arrows indicate that the item is a root cause and should be
tackle first
46
-a high number of incoming arrows indicate that the item is a key outcome and may
become a focus for planning either as a meaningful measure of overall success or as a
redefinition of the original issue under discussion
Example
47
48
Conclusions
Statististical QC is chiefly concerned in making sure that several procedures
and working arrangements are in place to provide for effective and efficient
statistical processes to minimize the risk of errors or weaknesses in
procedures or systems or in source material
Seven QC tools are most helpful in troubleshooting issues related to quality
All processes are affected by multiple factors and therefore statistical QC tools
can be applied to any process
The continuous use of these tools upgrades the personnel characteristics of the
people involved It enhances their ability to think generate ideas solve
problem and do proper planning
49
References asqorglearn-about-qualityseven-basic-quality-toolsoverviewhtml
httpsenwikipediaorgwikiSeven_Basic_Tools_of_Quality
wwwijergsorgfilesdocumentsAPPLICATION-45pd
httpssrcalionsciencecompdfQualityToolspdf
www3haorghkqehwiserdoc7bqtpdf
wwwmathmunca~variyathNew7QCToolspd
50
- 1 DEFINITION of Quality Control
- 3 Competitiveness
- 4 Customer Loyalty
- 5 Reputation
- 6 Compliance
- 7 Costs
- Benefits of Using Quality Control in Manufacturing
-
37
38
5) Matrix diagram
Purpose1) Explore the existence and the extent of relations between individual items in 2 sets
of factors or features and characteristics and express them in a symbolic form that is
easy to understand
2) Mostly used to understand the relations between the customer expectations as
expressed by the customers and product characteristics as designed manufactured and
tested by the manufacturer
Procedures1 Determine 2 sets of factors for which the relations are needed to be established
2 Divide the features and characteristics into primary secondary and tertiary
characteristics
3 Place the features vertically on the leg side of the matrix and characteristics
horizontally on top of the matrix
4 Enter the importance of the features on the column ager that for the tertiary
features10485775 In the main body of the matrix use the symbols to represent the degree of
connections between the feature and characteristics
6 Choose and define relationship symbols Most commonly used symbols are as
given below
Strong relationship=
Relationship =
Likely relationship=
Application
bull Matrix diagram can be used to solve problems by arranging data in such a way that
the relations between relevant factors are brought into sharp focus
bull There is no limit to the use of the tool
39
bull The most important application of matrix diagram is in clarifying relations between
individual features of customer requirements and individual product characteristics
Example 1
Matrix Diagram for Quality Functions and Responsibilities
40
41
6) Matrix Data Analysis Diagram1048577
Purpose
To present numerical data about two sets of factors in a matrix form and
analyze it to get numerical output
Can be applied in understanding the products and products characteristics
Procedure1048577
1 Decide the two factors whose relations are to be analyzed
2 Check the number of individual items in the two factors
3 Prepare a matrix to accommodate all the items of the two factors
4 Enter numerical data in the matrix
5 Give the diagram a suitable title
Example
42
43
44
7) Relationship diagram
This diagram clarifies the interrelations in a complex situation involving many
interrelated factors and serves to clarify the cause and effect relationships among
factors
Description
Relations diagram is defined as a technique used to solve problems that have complex
cause and effect relationships among a number of problems and factors that influence
them
Format
A special feature of relation diagram is its unrestricted Format However general
formats are as given below
1) Centrally converging relations diagram
The major item or problem to be solved is located in the center and the related factors
are arranged around the item or problem in such a way as to indicate close
relationships
2) Directionally intensive relations diagram
The major item or problem to be solved is located on one side of the diagram and the
various factors arranged in accordance with the flow of their major cause-and-effect
relationships on the other side
3) Relationship indication relations diagram
There are no restrictions on this format because the main point is to arrange the cause-
and-effect Relationships of the application items or factors so that they are expressed
in a straightforward manner in a Diagram
45
Procedure
1) Define the issueproblem in such a way that it is clearly understood and agreed on
by team members
2) Assemble the cross-functional team
3) Layout all the ideasissue cards that have been brought from other tools
4) Look for causeinfluence relationships between all ideas and draw relationship
arrows
a) Choose any of the ideas as a starting point and work through them in sequence
b)An outgoing arrow from an idea indicates that it is the stronger cause or influence
c) Draw only one way relationship arrows in the direction of the stronger cause or
Influence Make a decision on the stronger direction Do not draw two headed arrows
5) Review and revise the relationsrsquo diagram
6) Tally the number of outgoing and incoming arrows and select key items for further
planning
-record and clearly mark next to each issue the number of arrows going in and out of
it
-find the items with the highest number outgoing arrows and the items with the
highest number of incoming arrows
-a high number of outgoing arrows indicate that the item is a root cause and should be
tackle first
46
-a high number of incoming arrows indicate that the item is a key outcome and may
become a focus for planning either as a meaningful measure of overall success or as a
redefinition of the original issue under discussion
Example
47
48
Conclusions
Statististical QC is chiefly concerned in making sure that several procedures
and working arrangements are in place to provide for effective and efficient
statistical processes to minimize the risk of errors or weaknesses in
procedures or systems or in source material
Seven QC tools are most helpful in troubleshooting issues related to quality
All processes are affected by multiple factors and therefore statistical QC tools
can be applied to any process
The continuous use of these tools upgrades the personnel characteristics of the
people involved It enhances their ability to think generate ideas solve
problem and do proper planning
49
References asqorglearn-about-qualityseven-basic-quality-toolsoverviewhtml
httpsenwikipediaorgwikiSeven_Basic_Tools_of_Quality
wwwijergsorgfilesdocumentsAPPLICATION-45pd
httpssrcalionsciencecompdfQualityToolspdf
www3haorghkqehwiserdoc7bqtpdf
wwwmathmunca~variyathNew7QCToolspd
50
- 1 DEFINITION of Quality Control
- 3 Competitiveness
- 4 Customer Loyalty
- 5 Reputation
- 6 Compliance
- 7 Costs
- Benefits of Using Quality Control in Manufacturing
-
38
5) Matrix diagram
Purpose1) Explore the existence and the extent of relations between individual items in 2 sets
of factors or features and characteristics and express them in a symbolic form that is
easy to understand
2) Mostly used to understand the relations between the customer expectations as
expressed by the customers and product characteristics as designed manufactured and
tested by the manufacturer
Procedures1 Determine 2 sets of factors for which the relations are needed to be established
2 Divide the features and characteristics into primary secondary and tertiary
characteristics
3 Place the features vertically on the leg side of the matrix and characteristics
horizontally on top of the matrix
4 Enter the importance of the features on the column ager that for the tertiary
features10485775 In the main body of the matrix use the symbols to represent the degree of
connections between the feature and characteristics
6 Choose and define relationship symbols Most commonly used symbols are as
given below
Strong relationship=
Relationship =
Likely relationship=
Application
bull Matrix diagram can be used to solve problems by arranging data in such a way that
the relations between relevant factors are brought into sharp focus
bull There is no limit to the use of the tool
39
bull The most important application of matrix diagram is in clarifying relations between
individual features of customer requirements and individual product characteristics
Example 1
Matrix Diagram for Quality Functions and Responsibilities
40
41
6) Matrix Data Analysis Diagram1048577
Purpose
To present numerical data about two sets of factors in a matrix form and
analyze it to get numerical output
Can be applied in understanding the products and products characteristics
Procedure1048577
1 Decide the two factors whose relations are to be analyzed
2 Check the number of individual items in the two factors
3 Prepare a matrix to accommodate all the items of the two factors
4 Enter numerical data in the matrix
5 Give the diagram a suitable title
Example
42
43
44
7) Relationship diagram
This diagram clarifies the interrelations in a complex situation involving many
interrelated factors and serves to clarify the cause and effect relationships among
factors
Description
Relations diagram is defined as a technique used to solve problems that have complex
cause and effect relationships among a number of problems and factors that influence
them
Format
A special feature of relation diagram is its unrestricted Format However general
formats are as given below
1) Centrally converging relations diagram
The major item or problem to be solved is located in the center and the related factors
are arranged around the item or problem in such a way as to indicate close
relationships
2) Directionally intensive relations diagram
The major item or problem to be solved is located on one side of the diagram and the
various factors arranged in accordance with the flow of their major cause-and-effect
relationships on the other side
3) Relationship indication relations diagram
There are no restrictions on this format because the main point is to arrange the cause-
and-effect Relationships of the application items or factors so that they are expressed
in a straightforward manner in a Diagram
45
Procedure
1) Define the issueproblem in such a way that it is clearly understood and agreed on
by team members
2) Assemble the cross-functional team
3) Layout all the ideasissue cards that have been brought from other tools
4) Look for causeinfluence relationships between all ideas and draw relationship
arrows
a) Choose any of the ideas as a starting point and work through them in sequence
b)An outgoing arrow from an idea indicates that it is the stronger cause or influence
c) Draw only one way relationship arrows in the direction of the stronger cause or
Influence Make a decision on the stronger direction Do not draw two headed arrows
5) Review and revise the relationsrsquo diagram
6) Tally the number of outgoing and incoming arrows and select key items for further
planning
-record and clearly mark next to each issue the number of arrows going in and out of
it
-find the items with the highest number outgoing arrows and the items with the
highest number of incoming arrows
-a high number of outgoing arrows indicate that the item is a root cause and should be
tackle first
46
-a high number of incoming arrows indicate that the item is a key outcome and may
become a focus for planning either as a meaningful measure of overall success or as a
redefinition of the original issue under discussion
Example
47
48
Conclusions
Statististical QC is chiefly concerned in making sure that several procedures
and working arrangements are in place to provide for effective and efficient
statistical processes to minimize the risk of errors or weaknesses in
procedures or systems or in source material
Seven QC tools are most helpful in troubleshooting issues related to quality
All processes are affected by multiple factors and therefore statistical QC tools
can be applied to any process
The continuous use of these tools upgrades the personnel characteristics of the
people involved It enhances their ability to think generate ideas solve
problem and do proper planning
49
References asqorglearn-about-qualityseven-basic-quality-toolsoverviewhtml
httpsenwikipediaorgwikiSeven_Basic_Tools_of_Quality
wwwijergsorgfilesdocumentsAPPLICATION-45pd
httpssrcalionsciencecompdfQualityToolspdf
www3haorghkqehwiserdoc7bqtpdf
wwwmathmunca~variyathNew7QCToolspd
50
- 1 DEFINITION of Quality Control
- 3 Competitiveness
- 4 Customer Loyalty
- 5 Reputation
- 6 Compliance
- 7 Costs
- Benefits of Using Quality Control in Manufacturing
-
5) Matrix diagram
Purpose1) Explore the existence and the extent of relations between individual items in 2 sets
of factors or features and characteristics and express them in a symbolic form that is
easy to understand
2) Mostly used to understand the relations between the customer expectations as
expressed by the customers and product characteristics as designed manufactured and
tested by the manufacturer
Procedures1 Determine 2 sets of factors for which the relations are needed to be established
2 Divide the features and characteristics into primary secondary and tertiary
characteristics
3 Place the features vertically on the leg side of the matrix and characteristics
horizontally on top of the matrix
4 Enter the importance of the features on the column ager that for the tertiary
features10485775 In the main body of the matrix use the symbols to represent the degree of
connections between the feature and characteristics
6 Choose and define relationship symbols Most commonly used symbols are as
given below
Strong relationship=
Relationship =
Likely relationship=
Application
bull Matrix diagram can be used to solve problems by arranging data in such a way that
the relations between relevant factors are brought into sharp focus
bull There is no limit to the use of the tool
39
bull The most important application of matrix diagram is in clarifying relations between
individual features of customer requirements and individual product characteristics
Example 1
Matrix Diagram for Quality Functions and Responsibilities
40
41
6) Matrix Data Analysis Diagram1048577
Purpose
To present numerical data about two sets of factors in a matrix form and
analyze it to get numerical output
Can be applied in understanding the products and products characteristics
Procedure1048577
1 Decide the two factors whose relations are to be analyzed
2 Check the number of individual items in the two factors
3 Prepare a matrix to accommodate all the items of the two factors
4 Enter numerical data in the matrix
5 Give the diagram a suitable title
Example
42
43
44
7) Relationship diagram
This diagram clarifies the interrelations in a complex situation involving many
interrelated factors and serves to clarify the cause and effect relationships among
factors
Description
Relations diagram is defined as a technique used to solve problems that have complex
cause and effect relationships among a number of problems and factors that influence
them
Format
A special feature of relation diagram is its unrestricted Format However general
formats are as given below
1) Centrally converging relations diagram
The major item or problem to be solved is located in the center and the related factors
are arranged around the item or problem in such a way as to indicate close
relationships
2) Directionally intensive relations diagram
The major item or problem to be solved is located on one side of the diagram and the
various factors arranged in accordance with the flow of their major cause-and-effect
relationships on the other side
3) Relationship indication relations diagram
There are no restrictions on this format because the main point is to arrange the cause-
and-effect Relationships of the application items or factors so that they are expressed
in a straightforward manner in a Diagram
45
Procedure
1) Define the issueproblem in such a way that it is clearly understood and agreed on
by team members
2) Assemble the cross-functional team
3) Layout all the ideasissue cards that have been brought from other tools
4) Look for causeinfluence relationships between all ideas and draw relationship
arrows
a) Choose any of the ideas as a starting point and work through them in sequence
b)An outgoing arrow from an idea indicates that it is the stronger cause or influence
c) Draw only one way relationship arrows in the direction of the stronger cause or
Influence Make a decision on the stronger direction Do not draw two headed arrows
5) Review and revise the relationsrsquo diagram
6) Tally the number of outgoing and incoming arrows and select key items for further
planning
-record and clearly mark next to each issue the number of arrows going in and out of
it
-find the items with the highest number outgoing arrows and the items with the
highest number of incoming arrows
-a high number of outgoing arrows indicate that the item is a root cause and should be
tackle first
46
-a high number of incoming arrows indicate that the item is a key outcome and may
become a focus for planning either as a meaningful measure of overall success or as a
redefinition of the original issue under discussion
Example
47
48
Conclusions
Statististical QC is chiefly concerned in making sure that several procedures
and working arrangements are in place to provide for effective and efficient
statistical processes to minimize the risk of errors or weaknesses in
procedures or systems or in source material
Seven QC tools are most helpful in troubleshooting issues related to quality
All processes are affected by multiple factors and therefore statistical QC tools
can be applied to any process
The continuous use of these tools upgrades the personnel characteristics of the
people involved It enhances their ability to think generate ideas solve
problem and do proper planning
49
References asqorglearn-about-qualityseven-basic-quality-toolsoverviewhtml
httpsenwikipediaorgwikiSeven_Basic_Tools_of_Quality
wwwijergsorgfilesdocumentsAPPLICATION-45pd
httpssrcalionsciencecompdfQualityToolspdf
www3haorghkqehwiserdoc7bqtpdf
wwwmathmunca~variyathNew7QCToolspd
50
- 1 DEFINITION of Quality Control
- 3 Competitiveness
- 4 Customer Loyalty
- 5 Reputation
- 6 Compliance
- 7 Costs
- Benefits of Using Quality Control in Manufacturing
-
bull The most important application of matrix diagram is in clarifying relations between
individual features of customer requirements and individual product characteristics
Example 1
Matrix Diagram for Quality Functions and Responsibilities
40
41
6) Matrix Data Analysis Diagram1048577
Purpose
To present numerical data about two sets of factors in a matrix form and
analyze it to get numerical output
Can be applied in understanding the products and products characteristics
Procedure1048577
1 Decide the two factors whose relations are to be analyzed
2 Check the number of individual items in the two factors
3 Prepare a matrix to accommodate all the items of the two factors
4 Enter numerical data in the matrix
5 Give the diagram a suitable title
Example
42
43
44
7) Relationship diagram
This diagram clarifies the interrelations in a complex situation involving many
interrelated factors and serves to clarify the cause and effect relationships among
factors
Description
Relations diagram is defined as a technique used to solve problems that have complex
cause and effect relationships among a number of problems and factors that influence
them
Format
A special feature of relation diagram is its unrestricted Format However general
formats are as given below
1) Centrally converging relations diagram
The major item or problem to be solved is located in the center and the related factors
are arranged around the item or problem in such a way as to indicate close
relationships
2) Directionally intensive relations diagram
The major item or problem to be solved is located on one side of the diagram and the
various factors arranged in accordance with the flow of their major cause-and-effect
relationships on the other side
3) Relationship indication relations diagram
There are no restrictions on this format because the main point is to arrange the cause-
and-effect Relationships of the application items or factors so that they are expressed
in a straightforward manner in a Diagram
45
Procedure
1) Define the issueproblem in such a way that it is clearly understood and agreed on
by team members
2) Assemble the cross-functional team
3) Layout all the ideasissue cards that have been brought from other tools
4) Look for causeinfluence relationships between all ideas and draw relationship
arrows
a) Choose any of the ideas as a starting point and work through them in sequence
b)An outgoing arrow from an idea indicates that it is the stronger cause or influence
c) Draw only one way relationship arrows in the direction of the stronger cause or
Influence Make a decision on the stronger direction Do not draw two headed arrows
5) Review and revise the relationsrsquo diagram
6) Tally the number of outgoing and incoming arrows and select key items for further
planning
-record and clearly mark next to each issue the number of arrows going in and out of
it
-find the items with the highest number outgoing arrows and the items with the
highest number of incoming arrows
-a high number of outgoing arrows indicate that the item is a root cause and should be
tackle first
46
-a high number of incoming arrows indicate that the item is a key outcome and may
become a focus for planning either as a meaningful measure of overall success or as a
redefinition of the original issue under discussion
Example
47
48
Conclusions
Statististical QC is chiefly concerned in making sure that several procedures
and working arrangements are in place to provide for effective and efficient
statistical processes to minimize the risk of errors or weaknesses in
procedures or systems or in source material
Seven QC tools are most helpful in troubleshooting issues related to quality
All processes are affected by multiple factors and therefore statistical QC tools
can be applied to any process
The continuous use of these tools upgrades the personnel characteristics of the
people involved It enhances their ability to think generate ideas solve
problem and do proper planning
49
References asqorglearn-about-qualityseven-basic-quality-toolsoverviewhtml
httpsenwikipediaorgwikiSeven_Basic_Tools_of_Quality
wwwijergsorgfilesdocumentsAPPLICATION-45pd
httpssrcalionsciencecompdfQualityToolspdf
www3haorghkqehwiserdoc7bqtpdf
wwwmathmunca~variyathNew7QCToolspd
50
- 1 DEFINITION of Quality Control
- 3 Competitiveness
- 4 Customer Loyalty
- 5 Reputation
- 6 Compliance
- 7 Costs
- Benefits of Using Quality Control in Manufacturing
-
41
6) Matrix Data Analysis Diagram1048577
Purpose
To present numerical data about two sets of factors in a matrix form and
analyze it to get numerical output
Can be applied in understanding the products and products characteristics
Procedure1048577
1 Decide the two factors whose relations are to be analyzed
2 Check the number of individual items in the two factors
3 Prepare a matrix to accommodate all the items of the two factors
4 Enter numerical data in the matrix
5 Give the diagram a suitable title
Example
42
43
44
7) Relationship diagram
This diagram clarifies the interrelations in a complex situation involving many
interrelated factors and serves to clarify the cause and effect relationships among
factors
Description
Relations diagram is defined as a technique used to solve problems that have complex
cause and effect relationships among a number of problems and factors that influence
them
Format
A special feature of relation diagram is its unrestricted Format However general
formats are as given below
1) Centrally converging relations diagram
The major item or problem to be solved is located in the center and the related factors
are arranged around the item or problem in such a way as to indicate close
relationships
2) Directionally intensive relations diagram
The major item or problem to be solved is located on one side of the diagram and the
various factors arranged in accordance with the flow of their major cause-and-effect
relationships on the other side
3) Relationship indication relations diagram
There are no restrictions on this format because the main point is to arrange the cause-
and-effect Relationships of the application items or factors so that they are expressed
in a straightforward manner in a Diagram
45
Procedure
1) Define the issueproblem in such a way that it is clearly understood and agreed on
by team members
2) Assemble the cross-functional team
3) Layout all the ideasissue cards that have been brought from other tools
4) Look for causeinfluence relationships between all ideas and draw relationship
arrows
a) Choose any of the ideas as a starting point and work through them in sequence
b)An outgoing arrow from an idea indicates that it is the stronger cause or influence
c) Draw only one way relationship arrows in the direction of the stronger cause or
Influence Make a decision on the stronger direction Do not draw two headed arrows
5) Review and revise the relationsrsquo diagram
6) Tally the number of outgoing and incoming arrows and select key items for further
planning
-record and clearly mark next to each issue the number of arrows going in and out of
it
-find the items with the highest number outgoing arrows and the items with the
highest number of incoming arrows
-a high number of outgoing arrows indicate that the item is a root cause and should be
tackle first
46
-a high number of incoming arrows indicate that the item is a key outcome and may
become a focus for planning either as a meaningful measure of overall success or as a
redefinition of the original issue under discussion
Example
47
48
Conclusions
Statististical QC is chiefly concerned in making sure that several procedures
and working arrangements are in place to provide for effective and efficient
statistical processes to minimize the risk of errors or weaknesses in
procedures or systems or in source material
Seven QC tools are most helpful in troubleshooting issues related to quality
All processes are affected by multiple factors and therefore statistical QC tools
can be applied to any process
The continuous use of these tools upgrades the personnel characteristics of the
people involved It enhances their ability to think generate ideas solve
problem and do proper planning
49
References asqorglearn-about-qualityseven-basic-quality-toolsoverviewhtml
httpsenwikipediaorgwikiSeven_Basic_Tools_of_Quality
wwwijergsorgfilesdocumentsAPPLICATION-45pd
httpssrcalionsciencecompdfQualityToolspdf
www3haorghkqehwiserdoc7bqtpdf
wwwmathmunca~variyathNew7QCToolspd
50
- 1 DEFINITION of Quality Control
- 3 Competitiveness
- 4 Customer Loyalty
- 5 Reputation
- 6 Compliance
- 7 Costs
- Benefits of Using Quality Control in Manufacturing
-
6) Matrix Data Analysis Diagram1048577
Purpose
To present numerical data about two sets of factors in a matrix form and
analyze it to get numerical output
Can be applied in understanding the products and products characteristics
Procedure1048577
1 Decide the two factors whose relations are to be analyzed
2 Check the number of individual items in the two factors
3 Prepare a matrix to accommodate all the items of the two factors
4 Enter numerical data in the matrix
5 Give the diagram a suitable title
Example
42
43
44
7) Relationship diagram
This diagram clarifies the interrelations in a complex situation involving many
interrelated factors and serves to clarify the cause and effect relationships among
factors
Description
Relations diagram is defined as a technique used to solve problems that have complex
cause and effect relationships among a number of problems and factors that influence
them
Format
A special feature of relation diagram is its unrestricted Format However general
formats are as given below
1) Centrally converging relations diagram
The major item or problem to be solved is located in the center and the related factors
are arranged around the item or problem in such a way as to indicate close
relationships
2) Directionally intensive relations diagram
The major item or problem to be solved is located on one side of the diagram and the
various factors arranged in accordance with the flow of their major cause-and-effect
relationships on the other side
3) Relationship indication relations diagram
There are no restrictions on this format because the main point is to arrange the cause-
and-effect Relationships of the application items or factors so that they are expressed
in a straightforward manner in a Diagram
45
Procedure
1) Define the issueproblem in such a way that it is clearly understood and agreed on
by team members
2) Assemble the cross-functional team
3) Layout all the ideasissue cards that have been brought from other tools
4) Look for causeinfluence relationships between all ideas and draw relationship
arrows
a) Choose any of the ideas as a starting point and work through them in sequence
b)An outgoing arrow from an idea indicates that it is the stronger cause or influence
c) Draw only one way relationship arrows in the direction of the stronger cause or
Influence Make a decision on the stronger direction Do not draw two headed arrows
5) Review and revise the relationsrsquo diagram
6) Tally the number of outgoing and incoming arrows and select key items for further
planning
-record and clearly mark next to each issue the number of arrows going in and out of
it
-find the items with the highest number outgoing arrows and the items with the
highest number of incoming arrows
-a high number of outgoing arrows indicate that the item is a root cause and should be
tackle first
46
-a high number of incoming arrows indicate that the item is a key outcome and may
become a focus for planning either as a meaningful measure of overall success or as a
redefinition of the original issue under discussion
Example
47
48
Conclusions
Statististical QC is chiefly concerned in making sure that several procedures
and working arrangements are in place to provide for effective and efficient
statistical processes to minimize the risk of errors or weaknesses in
procedures or systems or in source material
Seven QC tools are most helpful in troubleshooting issues related to quality
All processes are affected by multiple factors and therefore statistical QC tools
can be applied to any process
The continuous use of these tools upgrades the personnel characteristics of the
people involved It enhances their ability to think generate ideas solve
problem and do proper planning
49
References asqorglearn-about-qualityseven-basic-quality-toolsoverviewhtml
httpsenwikipediaorgwikiSeven_Basic_Tools_of_Quality
wwwijergsorgfilesdocumentsAPPLICATION-45pd
httpssrcalionsciencecompdfQualityToolspdf
www3haorghkqehwiserdoc7bqtpdf
wwwmathmunca~variyathNew7QCToolspd
50
- 1 DEFINITION of Quality Control
- 3 Competitiveness
- 4 Customer Loyalty
- 5 Reputation
- 6 Compliance
- 7 Costs
- Benefits of Using Quality Control in Manufacturing
-
43
44
7) Relationship diagram
This diagram clarifies the interrelations in a complex situation involving many
interrelated factors and serves to clarify the cause and effect relationships among
factors
Description
Relations diagram is defined as a technique used to solve problems that have complex
cause and effect relationships among a number of problems and factors that influence
them
Format
A special feature of relation diagram is its unrestricted Format However general
formats are as given below
1) Centrally converging relations diagram
The major item or problem to be solved is located in the center and the related factors
are arranged around the item or problem in such a way as to indicate close
relationships
2) Directionally intensive relations diagram
The major item or problem to be solved is located on one side of the diagram and the
various factors arranged in accordance with the flow of their major cause-and-effect
relationships on the other side
3) Relationship indication relations diagram
There are no restrictions on this format because the main point is to arrange the cause-
and-effect Relationships of the application items or factors so that they are expressed
in a straightforward manner in a Diagram
45
Procedure
1) Define the issueproblem in such a way that it is clearly understood and agreed on
by team members
2) Assemble the cross-functional team
3) Layout all the ideasissue cards that have been brought from other tools
4) Look for causeinfluence relationships between all ideas and draw relationship
arrows
a) Choose any of the ideas as a starting point and work through them in sequence
b)An outgoing arrow from an idea indicates that it is the stronger cause or influence
c) Draw only one way relationship arrows in the direction of the stronger cause or
Influence Make a decision on the stronger direction Do not draw two headed arrows
5) Review and revise the relationsrsquo diagram
6) Tally the number of outgoing and incoming arrows and select key items for further
planning
-record and clearly mark next to each issue the number of arrows going in and out of
it
-find the items with the highest number outgoing arrows and the items with the
highest number of incoming arrows
-a high number of outgoing arrows indicate that the item is a root cause and should be
tackle first
46
-a high number of incoming arrows indicate that the item is a key outcome and may
become a focus for planning either as a meaningful measure of overall success or as a
redefinition of the original issue under discussion
Example
47
48
Conclusions
Statististical QC is chiefly concerned in making sure that several procedures
and working arrangements are in place to provide for effective and efficient
statistical processes to minimize the risk of errors or weaknesses in
procedures or systems or in source material
Seven QC tools are most helpful in troubleshooting issues related to quality
All processes are affected by multiple factors and therefore statistical QC tools
can be applied to any process
The continuous use of these tools upgrades the personnel characteristics of the
people involved It enhances their ability to think generate ideas solve
problem and do proper planning
49
References asqorglearn-about-qualityseven-basic-quality-toolsoverviewhtml
httpsenwikipediaorgwikiSeven_Basic_Tools_of_Quality
wwwijergsorgfilesdocumentsAPPLICATION-45pd
httpssrcalionsciencecompdfQualityToolspdf
www3haorghkqehwiserdoc7bqtpdf
wwwmathmunca~variyathNew7QCToolspd
50
- 1 DEFINITION of Quality Control
- 3 Competitiveness
- 4 Customer Loyalty
- 5 Reputation
- 6 Compliance
- 7 Costs
- Benefits of Using Quality Control in Manufacturing
-
44
7) Relationship diagram
This diagram clarifies the interrelations in a complex situation involving many
interrelated factors and serves to clarify the cause and effect relationships among
factors
Description
Relations diagram is defined as a technique used to solve problems that have complex
cause and effect relationships among a number of problems and factors that influence
them
Format
A special feature of relation diagram is its unrestricted Format However general
formats are as given below
1) Centrally converging relations diagram
The major item or problem to be solved is located in the center and the related factors
are arranged around the item or problem in such a way as to indicate close
relationships
2) Directionally intensive relations diagram
The major item or problem to be solved is located on one side of the diagram and the
various factors arranged in accordance with the flow of their major cause-and-effect
relationships on the other side
3) Relationship indication relations diagram
There are no restrictions on this format because the main point is to arrange the cause-
and-effect Relationships of the application items or factors so that they are expressed
in a straightforward manner in a Diagram
45
Procedure
1) Define the issueproblem in such a way that it is clearly understood and agreed on
by team members
2) Assemble the cross-functional team
3) Layout all the ideasissue cards that have been brought from other tools
4) Look for causeinfluence relationships between all ideas and draw relationship
arrows
a) Choose any of the ideas as a starting point and work through them in sequence
b)An outgoing arrow from an idea indicates that it is the stronger cause or influence
c) Draw only one way relationship arrows in the direction of the stronger cause or
Influence Make a decision on the stronger direction Do not draw two headed arrows
5) Review and revise the relationsrsquo diagram
6) Tally the number of outgoing and incoming arrows and select key items for further
planning
-record and clearly mark next to each issue the number of arrows going in and out of
it
-find the items with the highest number outgoing arrows and the items with the
highest number of incoming arrows
-a high number of outgoing arrows indicate that the item is a root cause and should be
tackle first
46
-a high number of incoming arrows indicate that the item is a key outcome and may
become a focus for planning either as a meaningful measure of overall success or as a
redefinition of the original issue under discussion
Example
47
48
Conclusions
Statististical QC is chiefly concerned in making sure that several procedures
and working arrangements are in place to provide for effective and efficient
statistical processes to minimize the risk of errors or weaknesses in
procedures or systems or in source material
Seven QC tools are most helpful in troubleshooting issues related to quality
All processes are affected by multiple factors and therefore statistical QC tools
can be applied to any process
The continuous use of these tools upgrades the personnel characteristics of the
people involved It enhances their ability to think generate ideas solve
problem and do proper planning
49
References asqorglearn-about-qualityseven-basic-quality-toolsoverviewhtml
httpsenwikipediaorgwikiSeven_Basic_Tools_of_Quality
wwwijergsorgfilesdocumentsAPPLICATION-45pd
httpssrcalionsciencecompdfQualityToolspdf
www3haorghkqehwiserdoc7bqtpdf
wwwmathmunca~variyathNew7QCToolspd
50
- 1 DEFINITION of Quality Control
- 3 Competitiveness
- 4 Customer Loyalty
- 5 Reputation
- 6 Compliance
- 7 Costs
- Benefits of Using Quality Control in Manufacturing
-
7) Relationship diagram
This diagram clarifies the interrelations in a complex situation involving many
interrelated factors and serves to clarify the cause and effect relationships among
factors
Description
Relations diagram is defined as a technique used to solve problems that have complex
cause and effect relationships among a number of problems and factors that influence
them
Format
A special feature of relation diagram is its unrestricted Format However general
formats are as given below
1) Centrally converging relations diagram
The major item or problem to be solved is located in the center and the related factors
are arranged around the item or problem in such a way as to indicate close
relationships
2) Directionally intensive relations diagram
The major item or problem to be solved is located on one side of the diagram and the
various factors arranged in accordance with the flow of their major cause-and-effect
relationships on the other side
3) Relationship indication relations diagram
There are no restrictions on this format because the main point is to arrange the cause-
and-effect Relationships of the application items or factors so that they are expressed
in a straightforward manner in a Diagram
45
Procedure
1) Define the issueproblem in such a way that it is clearly understood and agreed on
by team members
2) Assemble the cross-functional team
3) Layout all the ideasissue cards that have been brought from other tools
4) Look for causeinfluence relationships between all ideas and draw relationship
arrows
a) Choose any of the ideas as a starting point and work through them in sequence
b)An outgoing arrow from an idea indicates that it is the stronger cause or influence
c) Draw only one way relationship arrows in the direction of the stronger cause or
Influence Make a decision on the stronger direction Do not draw two headed arrows
5) Review and revise the relationsrsquo diagram
6) Tally the number of outgoing and incoming arrows and select key items for further
planning
-record and clearly mark next to each issue the number of arrows going in and out of
it
-find the items with the highest number outgoing arrows and the items with the
highest number of incoming arrows
-a high number of outgoing arrows indicate that the item is a root cause and should be
tackle first
46
-a high number of incoming arrows indicate that the item is a key outcome and may
become a focus for planning either as a meaningful measure of overall success or as a
redefinition of the original issue under discussion
Example
47
48
Conclusions
Statististical QC is chiefly concerned in making sure that several procedures
and working arrangements are in place to provide for effective and efficient
statistical processes to minimize the risk of errors or weaknesses in
procedures or systems or in source material
Seven QC tools are most helpful in troubleshooting issues related to quality
All processes are affected by multiple factors and therefore statistical QC tools
can be applied to any process
The continuous use of these tools upgrades the personnel characteristics of the
people involved It enhances their ability to think generate ideas solve
problem and do proper planning
49
References asqorglearn-about-qualityseven-basic-quality-toolsoverviewhtml
httpsenwikipediaorgwikiSeven_Basic_Tools_of_Quality
wwwijergsorgfilesdocumentsAPPLICATION-45pd
httpssrcalionsciencecompdfQualityToolspdf
www3haorghkqehwiserdoc7bqtpdf
wwwmathmunca~variyathNew7QCToolspd
50
- 1 DEFINITION of Quality Control
- 3 Competitiveness
- 4 Customer Loyalty
- 5 Reputation
- 6 Compliance
- 7 Costs
- Benefits of Using Quality Control in Manufacturing
-
Procedure
1) Define the issueproblem in such a way that it is clearly understood and agreed on
by team members
2) Assemble the cross-functional team
3) Layout all the ideasissue cards that have been brought from other tools
4) Look for causeinfluence relationships between all ideas and draw relationship
arrows
a) Choose any of the ideas as a starting point and work through them in sequence
b)An outgoing arrow from an idea indicates that it is the stronger cause or influence
c) Draw only one way relationship arrows in the direction of the stronger cause or
Influence Make a decision on the stronger direction Do not draw two headed arrows
5) Review and revise the relationsrsquo diagram
6) Tally the number of outgoing and incoming arrows and select key items for further
planning
-record and clearly mark next to each issue the number of arrows going in and out of
it
-find the items with the highest number outgoing arrows and the items with the
highest number of incoming arrows
-a high number of outgoing arrows indicate that the item is a root cause and should be
tackle first
46
-a high number of incoming arrows indicate that the item is a key outcome and may
become a focus for planning either as a meaningful measure of overall success or as a
redefinition of the original issue under discussion
Example
47
48
Conclusions
Statististical QC is chiefly concerned in making sure that several procedures
and working arrangements are in place to provide for effective and efficient
statistical processes to minimize the risk of errors or weaknesses in
procedures or systems or in source material
Seven QC tools are most helpful in troubleshooting issues related to quality
All processes are affected by multiple factors and therefore statistical QC tools
can be applied to any process
The continuous use of these tools upgrades the personnel characteristics of the
people involved It enhances their ability to think generate ideas solve
problem and do proper planning
49
References asqorglearn-about-qualityseven-basic-quality-toolsoverviewhtml
httpsenwikipediaorgwikiSeven_Basic_Tools_of_Quality
wwwijergsorgfilesdocumentsAPPLICATION-45pd
httpssrcalionsciencecompdfQualityToolspdf
www3haorghkqehwiserdoc7bqtpdf
wwwmathmunca~variyathNew7QCToolspd
50
- 1 DEFINITION of Quality Control
- 3 Competitiveness
- 4 Customer Loyalty
- 5 Reputation
- 6 Compliance
- 7 Costs
- Benefits of Using Quality Control in Manufacturing
-
-a high number of incoming arrows indicate that the item is a key outcome and may
become a focus for planning either as a meaningful measure of overall success or as a
redefinition of the original issue under discussion
Example
47
48
Conclusions
Statististical QC is chiefly concerned in making sure that several procedures
and working arrangements are in place to provide for effective and efficient
statistical processes to minimize the risk of errors or weaknesses in
procedures or systems or in source material
Seven QC tools are most helpful in troubleshooting issues related to quality
All processes are affected by multiple factors and therefore statistical QC tools
can be applied to any process
The continuous use of these tools upgrades the personnel characteristics of the
people involved It enhances their ability to think generate ideas solve
problem and do proper planning
49
References asqorglearn-about-qualityseven-basic-quality-toolsoverviewhtml
httpsenwikipediaorgwikiSeven_Basic_Tools_of_Quality
wwwijergsorgfilesdocumentsAPPLICATION-45pd
httpssrcalionsciencecompdfQualityToolspdf
www3haorghkqehwiserdoc7bqtpdf
wwwmathmunca~variyathNew7QCToolspd
50
- 1 DEFINITION of Quality Control
- 3 Competitiveness
- 4 Customer Loyalty
- 5 Reputation
- 6 Compliance
- 7 Costs
- Benefits of Using Quality Control in Manufacturing
-
48
Conclusions
Statististical QC is chiefly concerned in making sure that several procedures
and working arrangements are in place to provide for effective and efficient
statistical processes to minimize the risk of errors or weaknesses in
procedures or systems or in source material
Seven QC tools are most helpful in troubleshooting issues related to quality
All processes are affected by multiple factors and therefore statistical QC tools
can be applied to any process
The continuous use of these tools upgrades the personnel characteristics of the
people involved It enhances their ability to think generate ideas solve
problem and do proper planning
49
References asqorglearn-about-qualityseven-basic-quality-toolsoverviewhtml
httpsenwikipediaorgwikiSeven_Basic_Tools_of_Quality
wwwijergsorgfilesdocumentsAPPLICATION-45pd
httpssrcalionsciencecompdfQualityToolspdf
www3haorghkqehwiserdoc7bqtpdf
wwwmathmunca~variyathNew7QCToolspd
50
- 1 DEFINITION of Quality Control
- 3 Competitiveness
- 4 Customer Loyalty
- 5 Reputation
- 6 Compliance
- 7 Costs
- Benefits of Using Quality Control in Manufacturing
-
Conclusions
Statististical QC is chiefly concerned in making sure that several procedures
and working arrangements are in place to provide for effective and efficient
statistical processes to minimize the risk of errors or weaknesses in
procedures or systems or in source material
Seven QC tools are most helpful in troubleshooting issues related to quality
All processes are affected by multiple factors and therefore statistical QC tools
can be applied to any process
The continuous use of these tools upgrades the personnel characteristics of the
people involved It enhances their ability to think generate ideas solve
problem and do proper planning
49
References asqorglearn-about-qualityseven-basic-quality-toolsoverviewhtml
httpsenwikipediaorgwikiSeven_Basic_Tools_of_Quality
wwwijergsorgfilesdocumentsAPPLICATION-45pd
httpssrcalionsciencecompdfQualityToolspdf
www3haorghkqehwiserdoc7bqtpdf
wwwmathmunca~variyathNew7QCToolspd
50
- 1 DEFINITION of Quality Control
- 3 Competitiveness
- 4 Customer Loyalty
- 5 Reputation
- 6 Compliance
- 7 Costs
- Benefits of Using Quality Control in Manufacturing
-
References asqorglearn-about-qualityseven-basic-quality-toolsoverviewhtml
httpsenwikipediaorgwikiSeven_Basic_Tools_of_Quality
wwwijergsorgfilesdocumentsAPPLICATION-45pd
httpssrcalionsciencecompdfQualityToolspdf
www3haorghkqehwiserdoc7bqtpdf
wwwmathmunca~variyathNew7QCToolspd
50
- 1 DEFINITION of Quality Control
- 3 Competitiveness
- 4 Customer Loyalty
- 5 Reputation
- 6 Compliance
- 7 Costs
- Benefits of Using Quality Control in Manufacturing
-