Long-term outcomes of experimental evaluations are necessarily observed after long delays. We develop semiparametric methods for combining the short-term outcomes of experiments with observational measurements of short-term and long-term outcomes, in order to estimate long-term treatment effects. We characterize semiparametric efficiency bounds for various instances of this problem. These calculations facilitate the construction of several estimators. We analyze the finite-sample performance of these estimators with a simulation calibrated to data from an evaluation of the long-term effects of a poverty alleviation program.

翻译：实验评估的长期结果必然在长时间延迟后才能观察到。我们开发了半参数方法，通过将实验的短期结果与短期和长期结果的观测测量相结合，以估计长期治疗效应。我们刻画了该问题不同实例的半参数效率界。这些计算促进了多种估计量的构建。我们通过一项针对扶贫计划长期效果评估的校准模拟，分析了这些估计量的有限样本性能。