Stem and Leaf Plots

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Stem and Leaf Plots
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Definitions- Range

• Range- The difference between the greatest and
  least numbers in a data set
• Data set 23, 45, 60, 55, 80, 75, 15
• Largest number 80
• Smallest number 15
• Difference 80-15 65

The Range
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More on Range

• Range is not a measure of central tendency.
• It is a measure of variation..it describes the
  spread of the data.

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Stem and Leaf Plots

• What is a stem and leaf plot?
• It is a way to represent specific data.
• It organizes data so it can be analyzed
  visually and mathematically
• When is it appropriate to use a stem and leaf
  plot?
• When data can be grouped into intervals (stems)
  and the data values within the intervals can be
  plotted as the leaves.

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Stem and Leaf Plots
Parts of stem and leaf plots Stem Leaf
Stem
Leaf
This is the leaf
This is the stem
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Stem and Leaf Plots

• In a Stem and Leaf Plot, the data are organized
  from least to greatest. The digits of the
  greatest place value usually form the Stems, the
  next place value of digits form the leaves.

56
Leaf
Stem
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Stem and Leaf Plots

• How do we create them?
• We start with a data set
• All data should be in order from least to
  greatest.
• Each stem and each leaf must be represented.
• Always list the digit even if it is repeated

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Data set
Chick Weight (grams)
19 6 7 10
11 13 18 25
21 12 5 12
20 21 11 12

• Use the following data set to create a stem and
  leaf plot

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Stem and Leaf Plots

• Step 1 Create the graph

Stem
Leaf
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Stem and Leaf Plots

• Step 2 Choose the stems using digits in the tens
  place

19 6 7 10
11 13 18 25
21 12 5 12
20 21 11 12
What are the stems? (digits in the tens place)
0, 1, 2
The least value is 5, it has a 0 in the tens
place The greatest value is 25, it has a 2 in the
tens place
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Stem and Leaf Plots

• Step 3 List the stems in order from least to
  greatest.
• Stems 0, 1, 2

Stem
Leaf
0 12
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Stem and Leaf Plots

• Step 4 Order the leaves least to greatest

19 6 7 10
11 13 18 25
21 12 5 12
20 21 11 12
Stem
Leaf
0 1 2
5 6 7
0 1 1 2 2 2 3 8 9
0 1 1 5
The tens digits form the stems
Always write each leaf even if the data repeats
Always add a Key 12 12 g
The ones digit Forms the leaves
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Completing Graph

• What do we always do before completing a
  graph?????????????

Add a title!!!!
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Making Inferences

• When you analyze data, you can make inferences.
  That means, we can draw conclusions based on the
  data.

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Making Inferences
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• Find the mode ______
• Find the range ______
• Find the median _____

Miles Jessie biked
Stem
Leaf
25
12
0 1 2 3
5 5 6
0 0 0 0 1 2 2 5 8 8 9
1 2 5 8
The stem and leaf plot shows the number of miles
Jessie biked each day during the month of July.
0
21 21 miles
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Analyzing Data
What was the least number of miles Jessie biked
in July? _______ What was the largest number of
miles Jessie biked in July? _______ How many
days did Jessie bike only 10 miles? ____
Miles Jessie biked
Stem
Leaf
5
0 1 2 3
5 5 6
0 0 0 0 1 2 2 5 8 8 9
30
1 2 5 8
0
4

• 21 21 miles

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Making a stem and leaf plot
Make your own graph

• Use the data in the following table to create
  your own stem and leaf plot.

Quiz scores in Coach Bowens
Class
70 96 72 91
80 80 79 93
76 95 73 93
90 93 77 91
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Does it look like this?
Quiz scores in Coach Bowens Class
Stem
Leaf
7 8 9
0 2 3 6 7 9
0 0
0 1 1 3 3 3 5 6
91 91 on quiz
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Answer the questions about your graph

• What is the highest score on quiz? ____
• What was the lowest score on quiz?____
• What is the mode? ____
• What is the median ____
• What is the range of the quiz scores? ___

96
70
93
85
26
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Question

• Can we use stem and leaf plots to represent all
  data?

No
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Conclusion Stem and Leaf Plots

• Are easy to read
• Are easy to create
• Great graph to display data
• Can not be used for all data sets