Displaying Distributions With Graphs

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Displaying Distributions With Graphs

• Section 1.1

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A Picture is worth a thousand words

• First three rules for describing data
• Make a picture
• Make a picture
• Make a picture

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Categorical Data

• The following table displays the sales figures
  and market share (percent of total sales)
  achieved by several major soft drink companies in
  1999. That year a total of 9930 million cases of
  soft drink were sold.

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Company Cases Sold (Millions) Market Share (percent)
Coca-Cola 4377.5 44.1
Pepsi-Cola 3119.5 31.4
Dr. Pepper/7-up 1455.1 14.7
Cott Corp. 310.0 3.1
Nat. Bev. 205.0 2.1
Royal Crown 115.4 1.2
Other 347.5 3.4
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Creating a Bar Graph

• Title your graph
• Label axes
• Horizontal Axis is the categories
• Vertical Axis can be
• Counts (Frequency)
• Proportions (Relative Frequency)
• Percents
• Scale your axes
• Draw vertical bars to represent counts,
  proportions, or percents

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Creating a Pie Graph

• The most accurate way to create a pie graph is to
  use a computer. However pie graphs can be
  created using estimation, or by using a
  protractor and using the appropriate number of
  degrees to create the graph.

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• Bar Graphs show a bar that represents either the
  count, proportion, or percentage of each
  category. Bar graphs may or may not show all
  categories.
• Pie Graphs show how a whole divides into
  categories using either the proportion or
  percentage. To use a pie graph you must include
  all the categories that make up the whole.

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Further Resources

• Practice of Statistics pg 8-9
• Homework 1.1 2