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Section 2.2. More Graphs and Displays. Larson/Farber 4th ed. Section 2.2 Objectives. Graph quantitative data using stem-and-leaf plots and dot plots Graph qualitative data using pie charts and Pareto charts Graph paired data sets using scatter plots and time series charts. - PowerPoint PPT Presentation
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Section 2.2
More Graphs and Displays
Larson/Farber 4th ed.
Section 2.2 Objectives
• Graph quantitative data using stem-and-leaf plots and dot plots
• Graph qualitative data using pie charts and Pareto charts
• Graph paired data sets using scatter plots and time series charts
Larson/Farber 4th ed.
Graphing Quantitative Data Sets
Stem-and-leaf plot• Each number is separated into a stem and a leaf.• Similar to a histogram.• Still contains original data values.
Larson/Farber 4th ed.
Data: 21, 25, 25, 26, 27, 28, 30, 36, 36, 45
26
2 1 5 5 6 7 8
3 0 6 6
4 5
Example: Constructing a Stem-and-Leaf Plot
The following are the numbers of text messages sent last month by the cellular phone users on one floor of a college dormitory. Display the data in a stem-and-leaf plot.
Larson/Farber 4th ed.
149 167 162 127 130 180 160 167 221 145 137 194
207 150 254 262 244 297 137 204 166 174 180 151
Solution: Constructing a Stem-and-Leaf Plot
Larson/Farber 4th ed.
• The data entries go from a low of 127 to a high of 297.• Use the rightmost digit as the leaf. For instance,
127 = 12 | 7 and 297 = 29 | 7• List the stems, 12 to 29, to the left of a vertical line.• For each data entry, list a leaf to the right of its stem.
149 167 162 127 130 180 160 167 221 145 137 194
207 150 254 262 244 297 137 204 166 174 180 151
Solution: Constructing a Stem-and-Leaf Plot
Include a key to identify the values of the data.
12 7
13 77
14 59
15 1
16 2677
17 4
18 0
19 4
20 47
21
22 1
23
24 4
25 4
26 2
27
28
29 7
12|7 = 127
Graphing Quantitative Data Sets
Dot plot• Each data entry is plotted, using a point, above a
horizontal axis
Larson/Farber 4th ed.
Data: 21, 25, 25, 26, 27, 28, 30, 36, 36, 45
26
20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45
Example: Constructing a Dot Plot
Use a dot plot organize the text messaging data.
Larson/Farber 4th ed.
• So that each data entry is included in the dot plot, the horizontal axis should include numbers between 70 and 160.
• To represent a data entry, plot a point above the entry's position on the axis.
• If an entry is repeated, plot another point above the previous point.
155 159 144 129 105 145 126 116 130 114 122 112 112 142 126156 118 108 122 121 109 140 126 119 113 117 118 109 109 119139 139 122 78 133 126 123 145 121 134 124 119 132 133 124129 112 126 148 147
Solution: Constructing a Dot Plot
Larson/Farber 4th ed.
From the dot plot, you can see that most values cluster between 105 and 148 and the value that occurs the most is 126. You can also see that 78 is an unusual data value.
155 159 144 129 105 145 126 116 130 114 122 112 112 142 126156 118 108 122 121 109 140 126 119 113 117 118 109 109 119139 139 122 78 133 126 123 145 121 134 124 119 132 133 124129 112 126 148 147
Graphing Qualitative Data Sets
Pie Chart• A circle is divided into sectors that represent
categories.• The area of each sector is proportional to the
frequency of each category.
Larson/Farber 4th ed.
Example: Constructing a Pie Chart
The top seven American Kennel Club registrations (in thousands) in 2006. (Source: American Kennel Club)
Larson/Farber 4th ed.
Breed Labrador Retriever
Yorkshire Terrier
German Shepard
Golden Retriever Beagle Dachshund Boxer
# (in Thousands) 124 48 44 43 39 36 35
Solution: Constructing a Pie Chart
Larson/Farber 4th ed.
Breed Labrador Retriever
Yorkshire Terrier
German Shepard
Golden Retriever Beagle Dachshund Boxer
# (in Thousands) 124 48 44 43 39 36 35
Graphing Qualitative Data Sets
Pareto Chart• A vertical bar graph in which the height of each bar
represents frequency or relative frequency.• The bars are positioned in order of decreasing height,
with the tallest bar positioned at the left.
Larson/Farber 4th ed.
Categories
Fre
quen
cy
Solution: Constructing a Pareto Chart
Larson/Farber 4th ed.
Breed Labrador Retriever
Yorkshire Terrier
German Shepard
Golden Retriever Beagle Dachshund Boxer
# (in Thousands) 124 48 44 43 39 36 35
Graphing Paired Data Sets
Paired Data Sets• Each entry in one data set corresponds to one entry in
a second data set.• Graph using a scatter plot.
The ordered pairs are graphed aspoints in a coordinate plane.
Used to show the relationship between two quantitative variables.
Larson/Farber 4th ed. 54
x
y
Example: Interpreting a Scatter Plot
As the petal length increases, what tends to happen to the petal width?
Larson/Farber 4th ed.
Each point in the scatter plot represents thepetal length and petal width of one flower.
Graphing Paired Data Sets
Time Series• Data set is composed of quantitative entries taken at
regular intervals over a period of time. e.g., The amount of precipitation measured each
day for one month. • Use a time series chart to graph.
Larson/Farber 4th ed.
timeQ
uant
itat
ive
data
Solution: Constructing a Time Series Chart
Larson/Farber 4th ed.
The graph shows that the unemployment rate over a 12 year period.
Section 2.2 Summary
• Graphed quantitative data using stem-and-leaf plots and dot plots
• Graphed qualitative data using pie charts and Pareto charts
• Graphed paired data sets using scatter plots and time series charts
Larson/Farber 4th ed. 62
