In this paper, we revisit some common recommendations regarding the analysis of matched-pair and stratified experimental designs in the presence of attrition. Our main objective is to clarify a number of well-known claims about the practice of dropping pairs with an attrited unit when analyzing matched-pair designs. Contradictory advice appears in the literature about whether or not dropping pairs is beneficial or harmful, and stratifying into larger groups has been recommended as a resolution to the issue. To address these claims, we derive the estimands obtained from the difference-in-means estimator in a matched-pair design both when the observations from pairs with an attrited unit are retained and when they are dropped. We find limited evidence to support the claims that dropping pairs helps recover the average treatment effect, but we find that it may potentially help in recovering a convex-weighted average of conditional average treatment effects. We report similar findings for stratified designs when studying the estimands obtained from a regression of outcomes on treatment with and without strata fixed effects.

中文翻译：

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在存在磨损的情况下重新审视配对和分层实验的分析

在本文中，我们重新审视了一些关于在存在磨损的情况下分析配对和分层实验设计的常见建议。我们的主要目标是澄清一些关于在分析匹配对设计时用磨损单元掉对的做法的众所周知的主张。关于放弃配对是有益还是有害的文献中出现了相互矛盾的建议，并且建议将分层分成更大的组作为该问题的解决方案。为了解决这些问题，我们在保留和删除具有磨损单元的对的观察值时，从匹配对设计中的均值差估计器中获得估计量。我们发现有限的证据支持丢弃配对有助于恢复平均治疗效果的说法，但我们发现它可能有助于恢复条件平均治疗效果的凸加权平均值。在研究从有或没有分层固定效应的治疗结果回归得到的估计数时，我们报告了分层设计的类似发现。