The German health care reform of 2004 imposes a charge of 10 Euro for the first visit to a doctor in each quarter of the year. At first glance, there is no inhibiting effect of this fee on utilization in the German Socio-Economic Panel. However, this study reveals that the true effect is diluted...

Twin births are an important instrumental variable for the endogenous fertility decision. However, in many economic settings, twins are not exogenous as dizygotic twinning is known to be correlated with maternal characteristics and fertility treatments. Following the medical literature, we...

We document increased old-age mortality rates among Swedish twin mothers compared to non-twin mothers. Results are based on administrative data on mortality for the years 1990 to 2010. We argue that twins are an unplanned shock to fertility in the cohorts of older women considered. Deaths due to...

Heterogeneous effects are prevalent in many economic settings. As the functional form between outcomes and regressors is generally unknown a priori, a semiparametric negative binomial count data model is proposed which is based on the local likelihood approach and generalized product kernels....