Statistical Hypothesis Testing with SAS and R

Chapter 14

Tests on contingency tables

In this chapter we deal with the question of whether there is an association between two random variables or not. This question can be formulated in different ways. We can ask if the two random variables are independent or test for homogeneity. The corresponding tests are presented in Section 14.1. These are foremost the well-known Fisher's exact test and Pearson's -test. In Section 14.2 we test if two raters agree on their rating of the same issue. Section 14.3 deals with two risk measures, namely the odds ratio and the relative risk.

14.1 Tests on independence and homogeneity

In this chapter we deal with the two null hypotheses of independence and homogeneity. While a test of independence examines if there is an association between two random variables or not, a test of homogeneity tests if the marginal proportions are the same for different random variables. The test problems in this chapter can be described for the homogeneity hypothesis as well as for the independence hypothesis.

14.1.1 Fisher's exact test

Description:	Tests the hypothesis of independence or homogeneity in a contingency table.
Assumptions:	Data are at least measured on a nominal scale with two possible categories, labeled as and , for each of the two variables and ...