Excess zeros are encountered in many empirical count data applications. We provide a new explanation of extra zeros, related to the underlying stochastic process that generates events. The process has two rates, a lower rate until the first event, and a higher one thereafter. We derive the...

The paper evaluates the German health care reform of 1997, using the individual number of doctor visits as outcome measure. A new econometric model, the Probit-Poisson-log-normal model with correlated errors, describes the data better than existing count data models. Moreover, it has an...

The paper evaluates the German health care reform of 1997, using the individual number of doctor visits as outcome measure and data from the German Socio- Economic Panel for the years 1995-1999. A number of modified count data models allow to estimate the effect of the reform in different parts...

This paper reports on a re-evaluation of the German health care reform of 1997. A previous evaluation found a limited effect of a 4.4 percent reduction of the number of doctor visits in a sample of pharmacy customers. The re-evaluation based on a representative household survey, the German...

The German health care reform of 1997 provides a natural experiment for evaluating the price sensitivity of demand for physicians' services. As a part of the reform, co-payments for prescription drugs were increased step up to 200%. However, certain groups of people were exempted from the...

The German health care reform of 1997 provides a natural experiment for evaluating the price sensitivity of demand for physicians’ services. As part of the reform, copayments for prescription drugs were increased by up to 200 percent. However, certain groups of people were exempted from the...

The paper evaluates the German health care reform of 1997, using the individual number of doctor visits as outcome measure and data from the German Socio- Economic Panel for the years 1995-1999. A number of modified count data models allow to estimate the effect of the reform in different parts...

The paper evaluates the German health care reform of 1997, using the individual number of doctor visits as outcome measure. A new econometric model, the Probit-Poisson-log-normal model with correlated errors, describes the data better than existing count data models. Moreover, it has an...

The Paper evaluates the German health care reform of 1997, using the individual number of doctor visits as outcome measure. A new econometric model, the Probit-Poisson-log-normal model with correlated errors, describes the data better than existing count data models. Moreover, it has an...

This paper reports on a re-evaluation of the German health care reform of 1997. A previous evaluation found a limited effect of a 4.4 percent reduction of the number of doctor visits in a sample of pharmacy customers. The re-evaluation based on a representative household survey, the German...