Identifying Study Subjects

A study entitled Antidepressant Medication and Breast Cancer Risk (Amer. J. of Epi, late 1990s) stated in the methods section of the paper that Cases were an age-stratified (< 50 and 50 years of age) random sample of women aged 25-74 years diagnosed with primary breast cancer during 1995 and 1996 (pathology report confirmed) and recorded in the population-based Ontario Cancer Registry. As the 1-year survival for breast cancer is 90%, surrogate respondents were not used. Population controls, aged 25-74 years, were randomly sampled from the property assessment rolls of the Ontario Ministry of Finance; this database includes all home owners and tenants and lists age, sex, and address.

1. Discuss the authors approach to the identification of cases with respect to the potential for selection bias.
2. Discuss the authors approach to the identification of controls with respect to the potential for selection bias.
3. Does the decision not to allow surrogate respondents potentially affect selection bias?