Researchers using instrumental variables to investigate ordered treatments often recode treatment into an indicator for any exposure. We investigate this estimand under the assumption that the instruments shift compliers from no treatment to some but not from some treatment to more. We show that when there are extensive margin compliers only (EMCO) this estimand captures a weighted average of treatment effects that can be partially unbundled into each complier group's potential outcome means. We also establish an equivalence between EMCO and a two-factor selection model and apply our results to study treatment heterogeneity in the Oregon Health Insurance Experiment.

翻译：使用工具变量研究有序处理的研究人员通常将处理重新编码为是否有任何接触的指标。我们在假设工具将服从者从无治疗转移到某种程度，但不会从某种程度转移到更多治疗的条件下，研究该估计量。我们证明，当仅存在广泛边际服从者（EMCO）时，该估计量捕获了处理效应的加权平均值，并且可以将其部分分解为每个服从者组的潜在结果均值。我们还建立了EMCO与双因素选择模型之间的等价关系，并将我们的结果应用于俄勒冈健康保险实验中的处理异质性研究。