Question
A prospective cohort study was conducted to determine the risk of heart attack among men with varying levels of baldness. Third-year residents in dermatology conducted visual baldness assessments at the start of the study (which was before any heart attacks had occurred). Four levels of baldness were coded: non, minimal, moderate, and severe. The follow-up rate was closed to which of the following types of bias were surely avoided in this study?
Recall bias of the exposure information
Differential misclassification of the exposure
Non-differential misclassification of the exposure
Selection bias
Source: Aschengrau Chapter 10
