12.26 In a study to determine if hormone therapy increases risk of venous thrombosis in menopausal women, each person in a sample of 579 women who had been diagnosed with venous thrombosis was classified according to hormone use. Each woman in a sample of 2243 women who had not been diagnosed with venous thrombosis was also classified according to hormone use. Data from the study are given in the accompanying table (Journal of the American Medical Association [2004]: 1581–1587). The women in each of the two samples were selected at random from patients at a large HMO in the state of Washington.

a. Is there convincing evidence that the proportions falling into each of the hormone use categories is not the same for women who have been diagnosed with venous thrombosis and those who have not?

b. To what populations would it be reasonable to generalize the conclusions of Part (a)? Explain.

Current Hormone Use None Esterified Estrogen Conjugated Equine Estrogen Venous Thrombosis 372 86 121 No Venous Thrombosis 1439 515 289