Randomized trials (RTs) are used to learn about treatment effects. This paper studies identification of average treatment response (ATR) and average treatment effect (ATE) from RT data under various assumptions. The focus is the problem of external validity of the RT. RT data need not point identify the ATR or ATE because of selective participation in the RT. The paper reports partial‐identification and point‐identification results for the ATR and ATE based on RT data under a variety of assumptions. The results include assumptions sufficient to point identify the ATR or ATE from RT data. Under weaker assumptions, the ATR or ATE is partially identified. Further, attention is given to identification of the sign of the ATE and identification of whether participation in the RT is selective. Finally, identification from RT data is compared to identification from observational data.

中文翻译：

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确定选择性参与随机试验的治疗效果

随机试验（RTs）用于了解治疗效果。本文研究在各种假设下根据RT数据确定平均治疗反应（ATR）和平均治疗效果（ATE）的方法。重点是RT的外部有效性问题。由于有选择地参与RT，因此RT数据不需要点标识ATR或ATE。本文基于各种假设，根据RT数据报告了ATR和ATE的部分识别和点识别结果。结果包括足以从RT数据识别ATR或ATE的假设。在较弱的假设下，将部分识别ATR或ATE。此外，关注于ATE的符号的识别以及RT的参与是否是选择性的识别。最后，