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Data Presentation
Using Descriptive Graphs
Introduction to Business Statistics, 5e
Kvanli/Guynes/Pavur
(c)2000 South-Western College Publishing
Constructing a Frequency Distribution
1. Gather the data.
2. Arrange the data in an ordered array.
3. Select the number of classes.
4. Determine the class width.
5. Determine the class limits for each class.
6. Count the number of data items in each class.
7. Summarize into a frequency distribution table.Introduction to Business Statistics, 5e
Kvanli/Guynes/Pavur
(c)2000 South-Western College Publishing
Frequency Distribution
• Number of Classes (K) value chosen to best represent the data
• Class Width (CW)
range
number of classesH – LK
Introduction to Business Statistics, 5e
Kvanli/Guynes/Pavur
(c)2000 South-Western College Publishing
Frequency Distribution for Continuous Data
Introduction to Business Statistics, 5e
Kvanli/Guynes/Pavur
(c)2000 South-Western College Publishing
Frequency Distribution for Continuous Data
Introduction to Business Statistics, 5e
Kvanli/Guynes/Pavur
(c)2000 South-Western College Publishing
Frequency Distribution for Discrete Data
Introduction to Business Statistics, 5e
Kvanli/Guynes/Pavur
(c)2000 South-Western College Publishing
Histogram
A Histogram is a graphical representation of a frequency distribution for continuous data.
The height is proportional to the frequency of that class
Introduction to Business Statistics, 5e
Kvanli/Guynes/Pavur
(c)2000 South-Western College Publishing
Introduction to Business Statistics, 5e
Kvanli/Guynes/Pavur
(c)2000 South-Western College Publishing
Introduction to Business Statistics, 5e
Kvanli/Guynes/Pavur
(c)2000 South-Western College Publishing
Stem-and-Leaf Diagrams
Stem-and-Leaf Diagrams were developed to summarize data without loss of information.
Introduction to Business Statistics, 5e
Kvanli/Guynes/Pavur
(c)2000 South-Western College Publishing
Stem-and-Leaf DiagramsIllustration
Reports of the after-tax profits of 12 companies are(recorded as cents per dollar of revenue) asfollows:3.4, 4.5, 2.3, 2.7, 3.8, 5.9, 3.4, 4.7, 2.4, 4.1, 3.6, 5.1
Stem Leaf (unit = .1)
2345
3 4 74 4 6 81 5 7 1 9
Introduction to Business Statistics, 5e
Kvanli/Guynes/Pavur
(c)2000 South-Western College Publishing
Stem-and-Leaf S
tem
L
eaf
( uni
t = . 1
)
2 3 4 5
3 4
74
4 6
81
5 7
1 9
By rotating the Stem-and-Leaf we get an image of the shape of the data.
Introduction to Business Statistics, 5e
Kvanli/Guynes/Pavur
(c)2000 South-Western College Publishing
Figure 2.9
Introduction to Business Statistics, 5e
Kvanli/Guynes/Pavur
(c)2000 South-Western College Publishing
Frequency Polygon
A frequency polygon is a graph that represents the shape of the data. It can be conceptualized as a connection of the midpoints of the classes at the height specified by the frequency.
Introduction to Business Statistics, 5e
Kvanli/Guynes/Pavur
(c)2000 South-Western College Publishing
Relative Frequency Polygon
A relative frequency polygon is similar to a frequency polygon, except that the height is dictated by the relative frequency
Introduction to Business Statistics, 5e
Kvanli/Guynes/Pavur
(c)2000 South-Western College Publishing
Figure 2.17
Introduction to Business Statistics, 5e
Kvanli/Guynes/Pavur
(c)2000 South-Western College Publishing
Cumulative Frequencies
A Cumulative Frequency table provides information on the number of values that are less than the upper class limit.
Introduction to Business Statistics, 5e
Kvanli/Guynes/Pavur
(c)2000 South-Western College Publishing
Introduction to Business Statistics, 5e
Kvanli/Guynes/Pavur
(c)2000 South-Western College Publishing
Bar Charts
• Bar Charts are used for graphical representation of Nominal and Ordinal data.
• As with a Histogram the height of the bar is proportional to the number of values in the category.
Introduction to Business Statistics, 5e
Kvanli/Guynes/Pavur
(c)2000 South-Western College Publishing
Figure 2.20
Introduction to Business Statistics, 5e
Kvanli/Guynes/Pavur
(c)2000 South-Western College Publishing
Pie Chart
• The Pie Chart is an alternative to the Bar Chart for Nominal and Ordinal data.
• The proportion of the Pie represents the category’s percentage in the population or sample.
Introduction to Business Statistics, 5e
Kvanli/Guynes/Pavur
(c)2000 South-Western College Publishing
Figure 2.23
Deceptive Graphs
• If care is not taken in constructing graphs, the graph may not properly present the data.
• Also, Graphs can be purposely manipulated to provide false impressions of the data.
Introduction to Business Statistics, 5e
Kvanli/Guynes/Pavur
(c)2000 South-Western College Publishing
Common Deceptive GraphsFigure 2.26
Introduction to Business Statistics, 5e
Kvanli/Guynes/Pavur
(c)2000 South-Western College Publishing
Common Deceptive Graphs Figure 2.27
Introduction to Business Statistics, 5e
Kvanli/Guynes/Pavur
(c)2000 South-Western College Publishing
Common Deceptive Graphs Figure 2.28
Introduction to Business Statistics, 5e
Kvanli/Guynes/Pavur
(c)2000 South-Western College Publishing