Health Recommendations and Selection in Health Behaviors

Consider a case in which a new research finding links a health behavior with good health outcomes. A possible consequence is take-up of this behavior among individuals who engage in other positive health behaviors. If this occurs, later analyses of observational data may be biased by the change in selection. This paper evaluates these dynamic biases in empirical settings. Using data from vitamin supplementation and diet, I show that selection responds endogenously to health recommendations. These results highlight how spurious findings on health behaviors can be self-reinforcing. (JEL I12)