论文标题
样品窥探的治疗效果偏见：盲结果既不需要也不足够
Treatment Effect Bias from Sample Snooping: Blinding Outcomes is Neither Necessary nor Sufficient
论文作者
论文摘要
观察数据分析的流行指南指出，在确定匹配标准或倾向分数时，结果应视而不见。据说这种盲人是为了维持分析的“客观性”，并通过利用机会失衡来防止分析师捕鱼以取得积极的结果。与这个概念相反，我们表明结果蒙蔽并不足够防止钓鱼。如果可以从基线协变量大致预测结果的情况下，蒙蔽和未盲的分析师可以产生相同数量级的偏差。我们结合了分析结果和模拟来说明这种漏洞。最后，为了证明结果盲是防止偏见的必要，我们概述了估计对照组的平均治疗效果或对治疗的平均治疗效果的替代样品分配程序。该过程在最终分析步骤中使用了来自所有分区的所有结果数据，但不需要分析即可完全预先指定。
Popular guidance on observational data analysis states that outcomes should be blinded when determining matching criteria or propensity scores. Such a blinding is informally said to maintain the "objectivity" of the analysis, and to prevent analysts from fishing for positive results by exploiting chance imbalances. Contrary to this notion, we show that outcome blinding is not a sufficient safeguard against fishing. Blinded and unblinded analysts can produce bias of the same order of magnitude in cases where the outcomes can be approximately predicted from baseline covariates. We illustrate this vulnerability with a combination of analytical results and simulations. Finally, to show that outcome blinding is not necessary to prevent bias, we outline an alternative sample partitioning procedure for estimating the average treatment effect on the controls, or the average treatment effect on the treated. This procedure uses all of the the outcome data from all partitions in the final analysis step, but does not require the analysis to not be fully prespecified.
