Researchers conducted a study investigating the relationship between caffeinated coffee consumption and risk of depression in women. They collected data on 50,739 women free of depression symptoms at the start of the study in the year 1996, and these women were followed through 2006. The researchers used questionnaires to collect data on caffeinated coffee consumption, asked each individual about physician-diagnosed depression, and also asked about the use of antidepressants. The table below shows the distribution of incidences of depression by amount of caffeinated coffee consumption.

a) What type of test is appropriate for evaluating if there is an association between coffee intake and depression?

b) Write the hypotheses for the test you identified in part (a).

c) Calculate the overall proportion of women who do and do not suffer from depression.

Clinical Yes depression No Total 1 cup/week 670 11,545 12,215 Caffeinated coffee consumption 2-6 1 2-3 cups/week cup/day cups/day cups/day 373 905 564 6,244 16,329 11,726 6,617 17,234 12,290 95 2,288 2,383 Total 2,607 48,132 50,739