The extent to which survey experiments conducted with nonrepresentative convenience samples are generalizable to target populations depends critically on the degree of treatment effect heterogeneity. Recent inquiries have found a strong correspondence between sample average treatment effects estimated in nationally representative experiments and in replication studies conducted with convenience samples. We consider here two possible explanations: low levels of effect heterogeneity or high levels of effect heterogeneity that are unrelated to selection into the convenience sample. We analyze subgroup conditional average treatment effects using 27 original–replication study pairs (encompassing 101,745 individual survey responses) to assess the extent to which subgroup effect estimates generalize. While there are exceptions, the overwhelming pattern that emerges is one of treatment effect homogeneity, providing a partial explanation for strong correspondence across both unconditional and conditional average treatment effect estimates.

使用非代表性方便样本进行的调查实验可推广到目标人群的程度关键取决于治疗效果异质性的程度。最近的调查发现，在全国代表性实验中估计的样本平均治疗效果与对方便样本进行的复制研究中估计的样本平均治疗效果之间存在很强的对应关系。我们在这里考虑两种可能的解释：与选择方便样本无关的低水平的效果异质性或高水平的效果异质性。我们使用27个原始-重复研究对（包括101,745个单独的调查回答）来分析亚组的条件平均治疗效果，以评估亚组效果估计的普遍程度。虽然有例外，