Around the world many countries are about to break apart, stay together, join in federations or build supranational organisations. The political debate of the European constitution is embedded in this context. The question arises which policies have to be shifted to the central European level...

In panel data econometrics the Hausman test is of central importance to select an e±cient estimator of the models' slope parameters. When testing the null hypothesis of no correlation between unobserved heterogeneity and observable explanatory variables by means of the Hausman test model...