SEXRATIO - Natural Sex Ratios at Birth and Missing Women: New Evidence and Implications

自17世纪以来，解释出生性别比(SRB)的变化一直是社会科学家着迷的问题。这也是政策制定者的优先事项，因为SRB的变化往往表明性别选择性堕胎和对妇女和女孩的歧视。在过去的50年里，人口学家已经形成了一个普遍的共识，即出生性别比在不同群体中基本保持不变，即每100名女性出生105名男性，种族或民族之间的差异很小。然而，最近，一项新的生物学文献表明，母亲的状况可能会导致男性受孕的失败率更高。这两篇文献是直接矛盾的，因为生物学文献表明，母亲压力的慢性指标应该与异质性SRB相关，而这在大型人口数据集中通常是找不到的。具体地说，PI证明了所有以前的分析都未能适当地控制母体条件下的时不变异质性，并开发了一种新的方法来做到这一点。一旦实施，PI证明了这一新的方法证实了SRB的母体状况变化，挑战了关于SRB稳定性的科学共识，并协调了这些文献中相互矛盾的发现。该项目有三个主要目标。在项目1中，PI寻求在不同国家和环境中调查这些初步调查结果，从而就社会经济地位对SRB的影响建立新的科学共识。项目2采用新的方法，通过提供新的国家一级估计数，改进失踪妇女人数的全球估计数。在项目3中，我们试图调和文献中关于SRB、社会经济因素和母亲压力的各种长期谜题，包括战争期间和之后性别比例的变化、经济衰退和跨种族群体。

Explaining variation in sex-ratios at birth (SRBs) has been a fascination of social scientists since the 1600s. It is also a priority for policy makers, as changes in SRBs often indicate sex-selective abortion and discrimination against women and girls. Over the past 50 years, a general consensus among demographers has emerged, that sex ratios at birth are mostly constant at 105 male births per 100 females across groups, with only small variations by race or ethnicity. Recently however, a new biological literature suggests that maternal condition may induce male conceptions to be lost at higher rates. These two literatures are in direct contradiction to each other, as the biological literature suggests that chronic indicators of maternal stress should be associated with heterogeneous SRBs, which is generally not found in large population datasets.This project proposes a novel explanation for this contradiction. Specifically, the PI documents that all previous analyses fail to properly control for time-invariant heterogeneity in maternal condition, and develops a new methodology to do so. Once implemented, the PI demonstrates that this new methodology confirms that maternal condition changes of SRBs, challenging the scientific consensus on the constancy of SRBs and reconciling the contradictory findings of these literatures.This project has three main goals. In Project 1, the PI seeks to investigate these preliminary findings across various countries and settings, thereby establishing a new scientific consensus on the effect of socioeconomic status on SRBs. Project 2 utilizes the new methodology to refine global estimates of the number of missing women by providing new country-level estimates. In Project 3, we seek to reconcile various long-standing puzzles in the literature on SRBs, socioeconomic factors, and maternal stress, including changing sex ratios during and after wars, economic downturns, and across racial groups.