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arXiv 2106.05024econ.EMstat.ME
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线性回归中的污染偏误

Contamination Bias in Linear Regressions

Paul Goldsmith-Pinkham, Peter Hull, Michal Kolesár

AI总结:

本文指出多处理线性回归的估计值会受到其他处理效应非凸平均的污染,并提出三种避免污染偏误的估计方法,通过九个实证应用验证了观察性研究中污染偏误的显著性。

摘要:

我们研究具有多个处理变量和一组控制变量的回归,这些控制变量足够灵活以消除遗漏变量偏误。我们表明,这些回归通常无法估计异质性处理效应的凸平均——相反,每个处理效应的估计值会受到其他处理效应非凸平均的污染。我们讨论了三种避免此类污染偏误的估计方法,包括针对最容易估计的加权平均效应的方法。对九个实证应用的重新分析发现,在观察性研究中存在经济上和统计上显著的污染偏误;在实验研究中,由于倾向得分变异性较小,污染偏误更为有限。

英文摘要:

We study regressions with multiple treatments and a set of controls that is flexible enough to purge omitted variable bias. We show that these regressions generally fail to estimate convex averages of heterogeneous treatment effects -- instead, estimates of each treatment's effect are contaminated by non-convex averages of the effects of other treatments. We discuss three estimation approaches that avoid such contamination bias, including the targeting of easiest-to-estimate weighted average effects. A re-analysis of nine empirical applications finds economically and statistically meaningful contamination bias in observational studies; contamination bias in experimental studies is more limited due to smaller variability in propensity scores.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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