Graphs, Charts, and Tables - Describing Your Data

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• Graphs, Charts, and Tables - Describing Your Data

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Frequency Distributions

• A frequency distribution is the sum of a set of
  data that displays the number of observations in
  each of the distributions distinct categories or
  classes.

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Frequency Distribution of Years in
College(Figure 2-1)
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Relative Frequency

• The relative frequency is the proportion of total
  observations contained in a given category.

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Relative Frequency Distribution of Years in
College(Figure 2-3)
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Grouping Data Into Classes

• Continuous data Data whose possible values are
  uncountable and which may assume any value in an
  interval.
• Data array Data that have been sorted in
  ascending or descending order.
• Mutually exclusive classes Classes that do not
  overlap.
• All inclusive classes A set of classes that
  contains all the possible values.
• Equal width classes Distance between lowest
  possible value and highest possible value in each
  class is the same.

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Steps for Grouping Data Into Classes

• Step 1 Determine the number of groups or classes
  to use.
• Step 2 Establish the class width.

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Class Width
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Steps for Grouping Data Into Classes

• Step 1 Determine the number of groups or classes
  to use.
• Step 2 Establish the class width.
• Step 3 Determine the class boundaries for each
  class.

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Steps for Grouping Data Into Classes

• Step 1 Determine the number of groups or classes
  to use.
• Step 2 Establish the class width.
• Step 3 Determine the class boundaries for each
  class.
• Step 4 Count the number of values in each class.

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Frequency Histograms(Figure 1-2)
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Frequency Histograms

• A histogram shows three general types of
  information
• It provides visual indication of where the
  approximate center if the data is.
• We can gain an understanding of the degree of
  spread, or variation, in the data.
• We can observe the shape of the distribution.

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Histograms Showing Different Centers
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Histograms - Same Center, Different Spread