Statistics: Chi-Square Tests

Objectives

• Students will recognize that chi-squared tests are for counts of categorical data.
• Students will identify the appropriate chi-squared test to use for a given situation: X² Goodness of Fit Test, X² Test of Independence, or X² Test of Homogeneity.
• Students will learn how to calculate the degrees of freedom for each type of chi-squared test.
• Students will interpret the results of a chi-square test.

Vocabulary

• alpha
• categorical data
• chi-squared (X² distribution)
• degrees of freedom
• expected counts
• goodness-of-fit test
• observed counts
• p-value
• test of homogeneity
• test of independence 

About the Lesson

This lesson involves investigating chi-squared tests and distributions.
As a result, students will:

• Compare different scenarios and determine which chi-square test is appropriate.
• Write the appropriate null and alternative hypotheses for the given scenario.
• Determine the degrees of freedom for the chi-square test.
• Look at chi-square test results and make the correct decision to reject or fail to reject the null hypothesis and write their conclusions in context.