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2.2 Representing Two Categorical Variables

Part of Exploring Two-Variable Data in AP® Statistics. Read the opening section, then create a free account for the full interactive lesson, practice, and progress tracking.

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Segmented Bar Graphs

A segmented bar graph visualizes two categorical variables simultaneously.

Construction:

  1. Create one bar for each category of the first variable
  2. Divide each bar into segments based on the second variable
  3. Height of each segment = conditional relative frequency

Example: Shows proportion of students preferring each study method, broken down by grade level.

The key question: Are the conditional distributions the same across all categories?

  • If the segment proportions are the same → no association
  • If segment proportions differ → there IS an association

Side-by-side bar graph: Separate bars for each combination (non-stacked) — easier to compare exact values but harder to see totals.

In this unit

9 lessons

  1. 2.1Introducing Statistics: Are Variables Related?Preview lesson
  2. 2.2Representing Two Categorical VariablesThis lesson
  3. 2.3Statistics for Two Categorical VariablesPreview lesson
  4. 2.4Representing the Relationship Between Two Quantitative VariablesPreview lesson
  5. 2.5CorrelationPreview lesson
  6. 2.6Linear Regression ModelsPreview lesson
  7. 2.7ResidualsPreview lesson
  8. 2.8Least Squares RegressionPreview lesson
  9. 2.9Analyzing Departures from LinearityPreview lesson

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