Objectives

These provide an overview of the key concepts and computations you will encounter in each chapter. Read the Objectives before you study each chapter to get a sense of what the chapter is about. Reread the Objectives after you have studied each chapter to ensure that you have fully mastered each Objective listed.

This chapter presents hypothesis-testing procedures for nominal variables–variables whose values are categories. Accordingly, these procedures focus on the number of people in different categories, rather than on mean scores on some dimension. Two tests are described: the chi-square test for goodness of fit and the chi-square test for independence.

After reading this chapter, you should understand the following concepts and procedures:

• Chi-square statistic
• Observed and expected frequencies
• Computing the chi-square statistic
• Chi-square distribution and using a chi-square table
• The chi-square test for independence
• Contingency tables
• Assumptions for chi-square tests
• Effect size and power for a chi-square test for independence
• Controversy surrounding the minimum expected frequency
• How results of studies using chi-square tests are reported in research articles