A case-control study was conducted relating to the epidemiology of breast cancer and the possible involvement of dietary fats, along with other vitamins and nutrients. It included 2024 breast cancer cases admitted to Roswell Park Memorial Institute, Erie County, New York, from 1958 to 1965. A control group of 1463 was chosen from patients having no neoplasms and no pathology of gastrointestinal or reproductive systems. The primary factors being investigated were vitamins A and E (measured in international units per month). The data shown in Table E6.15 are for 1500 women over 54 years of age. Test to compare the proportions of subjects who consumed less vitamin A (a150,500 IU/ month), cases versus controls; state clearly your null and alternative hypotheses and choice of test size.

TABLE E6.15

Vitamin A (IU/month)                                       Cases                                     Controls

a150,500                                                                893                                          392

>150,500                                                               132                                             83

Total                                                                    1025                                          475