Proportional treatment effects for count response panel data: effects of binary exercise on health care demand
定义了适用于计数数据的条件与边际处理效应，利用健康与退休研究面板数据分析运动对医疗需求的影响，发现短期和长期运动对就诊次数和住院天数有不同方向的影响，但多数效应统计不显著。
We define conditional and marginal treatment effects appropriate for count data, and then conduct an empirical analysis for the effects of exercise on health care demand using panel data from the Health Retirement Study. The response variables are office visits to doctors and hospitalization days, and the treatments of interest are light and vigorous exercises. We found that short-run light exercise increases health care demand by 3-5%, whereas long-run light exercise decreases it by 3-6%. We also found that short-run vigorous exercise decreases health care demand by 1-2%, whereas long-run vigorous exercise decreases it by 1-3%. However, many of these numbers are not statistically significantly different from zero. These findings suggest that it will be difficult to reduce health care cost much by encouraging people to do more exercise--at least in the short-run.