The Consequences of Teenage Childbearing: Consistent Estimates When Abortion Makes Miscarriage Non‐random
研究发现，由于堕胎选择使流产不再随机，传统估计方法存在偏差；本文提出一致估计量，发现青少年生育的负面影响总体不利但温和。
Miscarriage, even if biologically random, is not socially random. Willingness to abort reduces miscarriage risk. Because abortions are favorably selected among pregnant teens, those miscarrying are less favorably selected than those giving birth or aborting but more favorably selected than those giving birth. Therefore, using miscarriage as an instrument is biased towards a benign view of teen motherhood while OLS on just those giving birth or miscarrying has the opposite bias. We derive a consistent estimator that reduces to a weighted average of OLS and IV when outcomes are independent of abortion timing. Estimated effects are generally adverse but modest.