# 8: The Chi-Square Distribution

- Page ID
- 5891

A chi-squared test is any statistical hypothesis test in which the sampling distribution of the test statistic is a chi-square distribution when the null hypothesis is true.

- 8.1: Prelude to The Chi-Square Distribution
- You will now study a new distribution, one that is used to determine the answers to such questions. This distribution is called the chi-square distribution.

- 8.2: Facts About the Chi-Square Distribution
- he chi-square distribution is a useful tool for assessment in a series of problem categories. These problem categories include primarily (i) whether a data set fits a particular distribution, (ii) whether the distributions of two populations are the same, (iii) whether two events might be independent, and (iv) whether there is a different variability than expected within a population.

- 8.3: Test of Independence
- Tests of independence involve using a contingency table of observed (data) values. The test statistic for a test of independence is similar to that of a goodness-of-fit test.

- 8.4: Test for Homogeneity
- The goodness–of–fit test can be used to decide whether a population fits a given distribution, but it will not suffice to decide whether two populations follow the same unknown distribution. A different test, called the test for homogeneity, can be used to draw a conclusion about whether two populations have the same distribution. To calculate the test statistic for a test for homogeneity, follow the same procedure as with the test of independence.

- 8.5: Comparison of the Chi-Square Tests
- You have seen the Chi-square test statistic used in three different circumstances. The following bulleted list is a summary that will help you decide which Chi-square test is the appropriate one to use.

- 8.6: The Chi-Square Distribution (Exercises)
- These are homework exercises to accompany the Textmap created for "Introductory Statistics" by OpenStax.

Barbara Illowsky and Susan Dean (De Anza College) with many other contributing authors. Content produced by OpenStax College is licensed under a Creative Commons Attribution License 4.0 license. Download for free at http://cnx.org/contents/30189442-699...b91b9de@18.114.