Kunz和Winkelmann的新作, 关于医疗保险的非线性模型，希望有帮助。

Summary:

From 2004 to 2012, the German social health insurance levied a co-payment for the first doctor visit in a calendar quarter.
We develop a new model for estimating the effect of such a co-payment on the individual number of visits per quarter. The
model combines a one-time increase in the otherwise constant hazard rate determining the timing of doctor visits with a
difference-in-differences strategy to identify the reform effect. An extended version of the model accounts for a mismatch
between reporting period and calendar quarter. Using data from the German Socio-Economic Panel, we do not find an effect
of the co-payment on demand for doctor visits.