Displaying Quantitative Data

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Displaying Quantitative Data
Dot Plots
Time Plots
Stem and Leaf Plots
Histograms
Box Plots
Remember to always describe these graphs using
CUSS after you have graphed your data.
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Dot Plots
Most Useful
- Small number of values
- Want to see individual values
- Want to see the shape of the distribution
- You have a small number of groups you want to
compare
Lets make a dot plot for the number of movies we
saw this summer.
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Time Plots
- Type of dot plot
- Plot data in order according to time
Example page 57.
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Stem and Leaf Plots
Sometimes just called a stem plot
Most Useful
- Relatively Small number of values
- Want to see the shape of the distribution
- You have two or more groups to compare
stem
leaf
You always need a key with stem plot.
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Example page 67 17
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Suppose the grades on a test were

1. 90 87 88 65 73 72 53 97 95
   73
2. 78 75 60 89 81 82 84 78 76
   68

Make a stem plot
Make a stem plot with split stems
9H 9L 8H 8L 7H 7L 6H 6L 5H 5L
9 8 7 6 5
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Back to back stem plots
Used to compare data
Page 70 35
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Histograms
Most Useful
- large number of values
- You dont need to see individual values
- Want to see the shape of the distribution
- You have a small number of groups you want to
compare
Draw backs
- Individuals working with the same data could
get different graphs
We will use our calculator to create histograms,
we will not create by hand
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Example 1 Number of pieces of mail received at a
school office for 36 days

• 123 70 90 80 78 72 52 103 138
• 92 93 118 118 106 95 131 59
• 115 97 100 128 130 66 135 76
• 143 100 88 110 75 60 115 105 85

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Example 2 The Degree of Reading Power (DRP)
scores for 44 third grade students
40 26 39 14 42 18 25 43 46 27 19 47 19 26
35 34 15 44 40 38 31 46 52 25 35 35 33 29
34 41 49 28 52 47 35 48 22 33 41 51 27 14
54 45
First let us divide the data into classes and
make a frequency chart
class frequency
10-19
20-29
30-39
40-49
50-59
In L1 enter the smallest number of the class (10,
20, etc)
In L2 enter the frequency
You will need the change the window for your
graph Xmin10, Xmax60, Xscl 10
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Example 3 page 66 15