1Role of Statistical Techniques

Prof. Dr. Masood Sadiq Butt

2Role of Statistical Techniques

During processing of products, there are variations in product parameter

Change in variables affect the quality of the product

Variations can be due to trouble shooting, variables that normally goes off are temp,

pressure and rate of fluid flow

These variations are ascertained using statistical analysis to meet the standard

3 Statistical techniques can help to measure,describe, analyze, interpret and model suchvariations

Statistical techniques help to get rid of suchvariation even with small data

Analysis of data help solve the variation inproduct parameters

Preventive action, if applied aptly, will lead tocontinual improvement in the finished product

For statistical analysis, sampling is of paramountimportance

4Why 100% sampling cant be done ?

We cant go for 100% sampling of the food product as

It is a time consuming exercise

Destructive sampling at such a mass level is not desired at industrial scale

Financial burden on the industry as well

5 Quality management system is that part of theorganization management system that focuseson the achievement of the results in relation tothe quality objectives

Quality management system is used to satisfythe needs, expectations and requirements of theinterested parties

Quality objectives complement other objectivesof the organization such as those related togrowth, funding, profitability, environment andoccupational health and safety

6 Quality management system facilitate planning,allocation of resources, definition of

complementary objectives and overall evaluation

of the effectiveness of organization

7Statistical Quality Control Tools

Seven statistical quality control tools include

1. Data sheet

2. Cause-and-effect diagram

3. Scatter diagram

4. Flowchart

5. Pareto chart (contains bars and line graph)

6. Histogram (graphical representation, showing a

visual impression of the distribution of data)

7. Control chart

8Data Sheet

Data from a table, form, query, view, or stored procedure displayed in a row-and-column format

Datasheet is a document summarizing the performanceand other technical characteristics of

Product

Machine

Component

Material

Subsystem (e.g. a power supply)

Software

9Data Sheet

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Data Sheet

Depending on the specific purpose, a data sheet mayoffer an average value, a typical value, a typical range,engineering tolerances,or a nominal value

A data sheet is usually used for technicalcommunication to describe technical characteristics ofan item or product

It can be published by the manufacturer to help peoplechoose products or to help use the products

By contrast, a technical specification is an explicit set ofrequirements to be satisfied by a material, product, orservice

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Cause-and-effect diagram

Kaoru Ishikawa, one of the founding fathers of modernmanagement, created the cause-and-effect diagram

Causes are arranged according to their level ofimportance or detail, resulting in a depiction ofrelationships and hierarchy of events

This helps to identify areas where there may beproblems, and allows for comparison of their relativeimportance

Cause-and-effect diagrams are typically constructedthrough brainstorming techniques

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Cause-and-effect diagram

Causes in a cause-and-effect diagram are frequentlyarranged into the four most common major categories

Manpower, methods, materials, and machinery (formanufacturing)

Equipment, policies, procedures, and people (foradministration and planning)

Its also called as fish bone diagram

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Cause-and-effect diagram/ fish bone diagram

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Scatter diagram

A scatter diagram or scatter chart is similar to a linegraph, except that the data points are plotted without a

connecting line drawn between them

Scatter charts are suitable for showing how data pointscompare to each other

At least two measured objects are needed for the query(one for the x-axis and one for the y-axis)

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Scatter diagram

Scatter diagrams are used to study possiblerelationships between two variables

Although these diagrams cannot prove that one variablecauses the other, they do indicate the existence of arelationship, as well as the strength of that relationship

In a scatter diagram the horizontal axis contains themeasured values of one variable and the vertical axisrepresents the measurements of the other variable

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Scatter diagram

The purpose of the scatter diagram is to display whathappens to one variable when the other variable is

changed

The diagram is used to test the theory that the twovariables are related

The slope of the diagram indicates the type ofrelationship that exists

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Flow Chart

A flowchart is defined as a graphic representationemploying standard graphic icons, usually a series ofblocks with each block representing one major process,that describes an operation that is studied or is used toplan stages of a project

Flowcharts provide an excellent form of documentationfor a process operation

These are useful when examining how various steps inan operation work together

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Flow Chart

A flowchart is an important project development anddocumentation tool

It visually records the steps, decisions, and actions ofany manufacturing or service operation and defines the

system key points, activities, and role performances

In a flowchart, the description of each process is writteninside the blocks

Any other significant information is usually writtenoutside the blocks

Each block is connected with an arrow to show wherethat process leads

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Flow Chart

The graphic icons generally used are:

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Flow Chart

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Pareto Chart

Alfredo Pareto was an Italian sociologist who suggestedthat 80% of all wealth in this country is owned by 20% ofthe people.

This supposition, known as the Pareto Principle wasfurther developed by business and industry leaders whofound that most of the quality problems were confined toa small number of machines or workers

In other words, 80% of problems come from 20% of theequipment or workforce.

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The Pareto Principle is used by business and industry to work to continually improve quality, whether it is a

product or a service

Quality improvement involves tackling one issue at a time

By addressing the ones causing the most difficulty (the 20% that are causing 80% of the problem),

improvements can be made and monitored for

continuous progress

Pareto charts are used to decide what steps need to be taken for quality improvement

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Pareto Chart

A Pareto chart graphically summarizes and displays therelative importance of the differences between groups ofdata

A Pareto chart can be constructed by segmenting therange of the data into groups (also called segments,bins, or categories)

The number of data points in each group is determinedand the Pareto chart constructed; however, unlike thebar chart, the Pareto chart is ordered in descendingfrequency magnitude

The groups are defined by the user

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Pareto Chart

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Histogram

A histogram is used to graphically summarize and display the distribution of a process data set

It can be constructed by segmenting the range of the data into equal-sized bins (segments, groups, or classes)

The vertical axis of the histogram is the frequency (the number of counts for each bin), and the horizontal axis is labeled with the range of the response variable

The number of data points in each bin is determined and the histogram constructed

The user defines the bin size

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Histogram

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Control Chart

Control charting is one of the most technicallysophisticated tools of statistical quality control

Dr. Walter A. Shewhart developed it in the 1920s as astatistical approach to the study of manufacturing

process variation for the purpose of improving the

economic effectiveness of the process

These methods are based on continuous monitoring ofprocess variation

A control chart is a graphical display of a qualitycharacteristic that has been measured or computed from

a sample vs. the sample number or time

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Control Chart

The chart contains a center line that represents theaverage value of the quality characteristic corresponding

to the in-control state

Two other horizontal lines called the upper control limit(UCL) and the lower control limit (LCL) are also drawn

These control limits are chosen so that if the process isin control, nearly all of the sample points will fall between

them

As long as the points plot within the control limits, theprocess is assumed to be in control and no action is

necessary

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Control charts are universally used to present qualitydata

They are sufficiently simple to interpret so thatmisunderstandings are avoided

Regardless of type, control charts all contain a fewfundamental characteristics:

They contain upper and lower control limits within which allobservations will lie if the process is under control

They contain a center line which is usually considered thetarget value for the process

They generally show numbers along the vertical axis todefine the values of the control limits and observations

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Control Chart

Control charts are used as a proven technique for

improving productivity tool in defect prevention prevent unnecessary process adjustments provide diagnostic information provide information about process capability

A typical example of a control chart in the food industry isthat used for net weight control

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Control Chart

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Relationship b/w QMS and Excellence Models

Approaches of QMS are based on certain principles that help to

1. Enable an organization to identify strengths and weaknesses

2. Contain provision for evaluation against generic models

3. Provide a basis for continual improvement

4. Contain provision for external recognition

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Relationship b/w QMS and Excellence Models

ISO 9000 family of standards providerequirements for QMS and guidance forperformance, improvement, evaluation

Excellence models contain criteria that enablecomparative evaluation of organizationalperformance and is applicable to all activitiesand interested parties of an organization

Assessment criteria in excellence modelsprovide a basis for an organization to compareits performance with the performance of otherorganizations