6.20 For K = 1, the generalized CMH correlation statistic equals formula (2.10).

When there truly is a trend, Section 2.5.3 noted that this test is more powerful than the X2 and G2 tests of Section 2.4.3. To illustrate, for Table 6.12 on job satisfaction and income, construct the marginal 4 × 4 table.

a. Show that the Pearson X2 = 11.5 with df = 9 (P = 0.24). Show that the correlation statistic with equally-spaced scores is M2 = 7.6 based on df = 1 (P = 0.006). Interpret.

b. Conduct an analysis with a model for which you would expect the test of the income effect also to be powerful.