Equivalent Tests Assume that a contingency table has two rows and two columns with frequencies of a and b in the first row and frequencies of c and d in the second row.

a. Verify that the test statistic can be expressed as

b. Let and let Show that the test statistic where and is such that z2 5 x2 [the same result as in part (a)]. This result shows that the chisquare test involving a 2 3 2 table is equivalent to the test for the difference between two proportions, as described in Section 9-2.