12. GallagherThompson and her colleagues (2001) compared 27 wives who were caring for their husbands who had Alzheimer’s disease to 27 wives in which neither partner had Alzheimer’s. The two groups of wives were otherwise similar in terms of age, number of years married, and social economic status.

Table 10 (reproduced from their Table 1) shows some of their results. Focusing on the Geriatric Depression Scale (the first row of the table) and the Mutuality Scale for Shared Values (the last row in the table), explain these results to a person who knows about the t test for a single sample but is unfamiliar with the t test for independent means.