Question

Suppose you are interested in evaluating the association of multivitamins and miscarriage. You write a grant proposal and are fortunate to obtain funding to conduct a pilot case-control study (Study A) among women who reported having a miscarriage and a set of age-matched controls. The study is poorly funded, however, and you don’t have the resources to implement a standardized questionnaire with which to collect the multivitamin use data – you instead go and conduct a free-form interview to elicit this information. After this study has concluded, you obtain more funding to conduct another, larger casecontrol study (Study B). This study has better funding and enables you to implement a standardized questionnaire.

Question: Identify a particular type of bias that might affect Study A but NOT Study B and justify your answer. By “particular type”, be more specific than “information” or “selection” bias using the readings you have done in class.

Answer 1