The effect of sibling size on childrenʹs health: a regression discontinuity design approach based on Chinaʹs one-child policy

A major challenge to the empirical studies on the effect of sibling size on childrenʹs health is the endogeneity of family size. The radical one-child policy implemented in 1979 in China provides us with a unique opportunity to apply a regression discontinuity design method to examine this issue, which requires much weaker assumptions than the IV approaches used in previous studies. Our results indicate that although there are statistically significant associations between sibling size and childrenʹs health, there is no evidence for the quantity–quality trade-off.