In this paper the seasonal unit root test of Hylleberg et al. (1990) is generalized to cover a heterogenous panel. The procedure follows the work of Im, Pesaran and Shin (2002). Test statistics are proposed and critical values are obtained by simulations. Moreover, the properties of the tests...

We study a random effects censored regression model in the context of repeated games. Introducing a feedback variable into the model leads to violation of the strict exogeneity assumption, thus rendering the random effects estimator inconsistent. Using the example of contributions to a public...

This paper analyzes the link between the diffusion of information- and communication technology (ICT) and both the skill structure and employment expectations of the different skill categories. The analysis is based on cross-sectional data for 4150 German firms conducted in mid-2000. The...

Interaction effects capture the impact of one explanatory variable x 1 on the marginal effect of another explanatory variable x 2. To explore interaction effects, the so-called interaction terms x 1 x 2 are typically included in estimation specifications. While in linear models the effect of a...