The diffusion of knowledge in the world generates positive externalities if knowledge flows increase the productivity of R&D. Our work analyzes knowledge diffusion and knowledge externalities in generating innovation and in determining productivity. We first estimate the determinants of...

I study a model of geopolitical organization endogenizing the size of nations, of their public spending and of their degree of openness. The optimal geography may not be a stable equilibrium and the Alesina-Spolaore bias toward too many nations tends to be confirmed. However, multiple equilibria...

We describe a model of international, multidimensional policy coordination where countries can enter into selective and separate agreements with different partners along different policy dimensions. The model is used to examine the implications of negotiation tie-in - the requirement that...

We compare trends in mortality, nutritional status and food supply to other living standard indicators for the early years of the Nazi period. We find that Germany experienced a substantial increase in mortality rates in most age groups in the mid-1930s, even relative to those of 1932, the worst...

This paper presents estimates of world output growth from 1970 to 2000, the distribution of income among countries and persons for the years 1980, 1990 and 2000, and world poverty rates for the same years. It also presents the results of a series of simulation exercises that attempt isolate the...