Sex Selection and Gender Balance
研究了父母可选择子女性别时均衡性别比的形成，发现重男轻女导致男性过剩和婚姻市场拥挤，降低福利；但在人口增长导致女性过剩时，性别选择可能改善福利。
We model the equilibrium sex ratio when parents can choose the sex of their child. With intrinsic son preference, sex selection results in a male-biased sex ratio. This is inefficient due to a marriage market congestion externality. Medical innovations that facilitate selection aggravate the inefficiency. If son preference arises endogenously, due to population growth causing an excess supply of women on the marriage market, selection may improve welfare. Empirically, sex selection causes an excess of males and reduces welfare in China. In most parts of India, cohort sizes are growing, implying an excess supply of women.