Socioeconomic Status and Sickness Absence - What do twins tell us about causality?

The purpose of this study is to empirically investigate causal effects between socioeconomic status and absence from the workplace due to sickness. To be able to conclude that income causally affects health it is important to control for both reverse causality and unobserved heterogeneity. This study uses a Swedish sample of female twins and a semiparametric censored fixed-effects model. Spousal income is correlated in cross-section with the share of total income that comes from benefits due to sickness absence. Results from this twin study indicate that male spousal income, i.e. a non-shared environmental influence, does not have a causal effect.