This paper discusses identification and estimation of causal intensive margin effects. The causal intensive margin effect is defined as the treatment effect on the outcome of individuals with a positive outcome irrespective of whether they are treated or not, and is of interest for outcomes with corner solutions. The main issue is to deal with a potential selection problem that arises when conditioning on positive outcomes. We propose using difference-in-difference methods - conditional on positive outcomes - to estimate causal intensive margin effects. We derive sufficient conditions under which the difference-in-difference estimator identifies the causal intensive margin effect. We apply the methodology to estimate the causal intensive margin effect of reaching the full retirement age on working hours.

中文翻译：

---

差异差异法识别和估算集约化边际效应

本文讨论了因果密集集约效应的识别和估计。因果密集集约效应定义为对具有阳性结果的个体的结局的治疗效果，而不论其是否得到治疗，并且对于具有角点解决方案的结局很感兴趣。主要问题是处理以积极成果为条件时出现的潜在选择问题。我们建议使用差异差异方法（以正面结果为条件）来估计因果关系密集边际效应。我们得出了足够的条件，在这些条件下，差异差异估计量可以确定因果密集的边际效应。我们采用该方法来估算达到完全退休年龄对工作时间的因果密集集约效应。