Bakirci and colleagues¹ describe a high turnover of the workforce in cotton spinning mills and try to analyse if the high turnover is health driven. These observations actually relate to one of the driving forces underlying the so called “healthy worker effect”. The healthy worker effect was probably first described by William Ogle in an appendix of the Registrar General’s report on mortality in England and Wales.² It refers to the observation that the working population is healthier than the general population. Ogle identified two kinds of selection responsible: one working at the time of hire, and the other working at the time of employment. The first selectively attracts or …