The effect of sibling size on children's health: a regression discontinuity design approach based on China's one-child policy

•Endogeneity of family size is a major challenge to the empirical studies.•One-child policy in China allows us to apply a RD design method.•We find negative associations between sibling size and children's health.•We do not find evidence for the quantity-quality trade-off.

A major challenge to the empirical studies on the effect of sibling size on children's 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 children's health, there is no evidence for the quantity-quality trade-off.