A Note on the Dependence of Health on Age and Education

When investigating relationships between education and health, one has to take age into account. Conditioning on age entails conditioning on surviving, which has been argued to lead to a potential selection bias. In this note, I argue that surviving should be considered as a necessary precondition for the relationships of interest and, therefore, not as a possible source of bias. I criticize models of health trajectories that do not condition on surviving.