AP®︎ Statistics (pre-2026) Unit 8: Notes & Study Guide
Prepare for your quiz, test, or the AP exam with a comprehensive review on Unit 8 of AP Statistics (pre-2026) – Inference for Categorical Data: Chi-Square.
Unit 8: Inference for Categorical Data: Chi-Square
How to test whether categorical variables are independent or follow an expected distribution using chi-square.
Begin with Topic 8.1: Introducing Statistics: A...To review Unit 8, go through each of the 7 topics below.
Everything you actually need to know for your Unit 8 test, pulled directly from the AP® Statistics (pre-2026) curriculum.
Introducing Statistics: Are My Results Unexpected?
Introducing Statistics: Are My Results Unexpected?
- When Observed Counts Don’t Match Expected Counts
- Random Variation vs Evidence Against a Claim
- How Sample Size Changes the Story
Setting Up a Chi-Square Goodness of Fit Test
Setting Up a Chi-Square Goodness of Fit Test
- What a Chi-Square Goodness-of-Fit Test Is
- Expected Counts and the Chi-Square Statistic
- Chi-Square Distributions
Carrying Out a Chi-Square Test for Goodness of Fit
Carrying Out a Chi-Square Test for Goodness of Fit
- The Chi-Square Test Statistic for Goodness of Fit
- Calculating the Chi-Square Statistic
- Finding and Interpreting the p-Value
Expected Counts in Two-Way Tables
Expected Counts in Two-Way Tables
- Two-Way Tables and What “Expected” Means
- The Expected Count Formula
- Why This Formula Makes Sense
Setting Up a Chi-Square Test for Homogeneity or Independence
Setting Up a Chi-Square Test for Homogeneity or Independence
- Chi-Square Tests for Homogeneity and Independence
- Choosing the Right Test
- Writing the Hypotheses
Carrying Out a Chi-Square Test for Homogeneity or Independence
Carrying Out a Chi-Square Test for Homogeneity or Independence
- The Chi-Square Test Statistic
- Degrees of Freedom
- Finding the P-Value
Skills Focus: Selecting an Appropriate Inference Procedure for Categorical Data
Skills Focus: Selecting an Appropriate Inference Procedure for Categorical Data
- What categorical inference is trying to do
- The full set of categorical inference procedures
- Independence vs Homogeneity
Notes
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