We ask whether a PAYG-financed social security system is welfare improving in an economy with idiosyncratic and aggregate risk. We argue that interactions between the two risks are important for this question. One is a direct interaction in the form of a countercyclical variance of idiosyncratic...

When markets are incomplete, social security can partially insure against idiosyncratic and aggregate risks. We incorporate both risks into an analytically tractable model with two overlapping generations and demonstrate that they interact over the life-cycle. The interactions appear even though...

It is now a commonplace that the unfunded public pension systems of many OECD countries will run into severe financing problems in the coming decades due to a dramatically increasing pensioner/worker ratio. While this diagnosis is completely undisputed, there is still a vigorous debate on the...

When markets are incomplete, social security can partially insure against idiosyncratic and aggregate risks. We incorporate both risks into an analytically tractable model with two overlapping generations. We derive the equilibrium dynamics in closed form and show that joint presence of both...

Kaum eine ordnungspolitische oder regulatorische Frage hat in der deutschen Telekommunikationsbranche wohl in den letzten Jahren für so viel Aufruhr gesorgt, wie die Einführung des neuen §9a in das Telekommunikationsgesetz (TKG). Die neue Vorschrift sieht vor, dass die Bundesnetzagentur...

In recent years a number of panel estimators have been suggested for sample selection models, where both the selection equation and the equation of interest contain individual effects which are correlated with the explanatory variables. We review and compare some of these estimators, and apply...