In the preceding chapter, we used the normal approximation to the binomial distribution to conduct tests of hypotheses for two independent proportions. However, we could have achieved the same results using an alternative technique. When working with nominal data that have been grouped into categories, we often arrange the counts in a tabular format known as a contingency table. In the simplest case, two dichotomous random variables are involved; the rows of the table represent the outcomes of one variable, and the columns represent the outcomes of the other. The entries in the table are the counts that correspond to a particular combination of categories.