Carefully consider the following questions. Write down your answers (1 - 2 paragraphs) for question # 1 within a word document and submit your answers to your seminar leader. Be prepared to discuss all questions during the seminar section.

1. Why is the selection of controls important? What methods of control selection do you know? What principles should we follow when selecting controls?
2. What are the limitations of using questionnaires to assess exposure status in study subjects? What kind of bias could be introduced by the use of questionnaires in determining exposure status? If present, what could be the effects of this bias on the study findings? Does our study design limit or avoid this bias?
3. Epidemiologic case-control studies often report increased risk of an event given exposure, but we know that we can only calculate the odds ratio in a case-control study as opposed to a risk ratio. Is it important to distinguish between a risk ratio and an odds ratio? When does Odds Ratio approximate the Risk Ratio? When does it approximate the Rate Ratio?