Essays in Macroeconomics

A long-standing and fascinating puzzle in economics is the understanding of the determinants that make some countries poor while other rich. This question can be summarized by the following quote, taken from the Lucas' essay On the Mechanics of Economic Development, which reads as follows Is there some action a government of India could take that would lead the Indian economy to grow like Indonesia's or Egypt's?This thesis, from a macroeconomic perspective, has not the ambition to provide a full and clear answer to the above mentioned issues. Rather, it attempts to give a partial but sensible contribution dealing with two dierent but deeply intertwined topics.The first chapter studies the interplay between infrastructure, informality and high skilled migration through a macroeconomic model which aims to de- pict a developing stylized country. In fact, infrastructure and human capital are two widely recognized key ingredients to achieve development. Large informal sector and substantial high skilled migration ows characterize developing countries eventually preventing both infrastructure and human capital accumulation. Two dierent frameworks are considered. In the rst one high skilled migration ows are left exogenous to the model while in the second one the brain drain phenomena is fully accounted by the model. Theoretical results are derived along with dynamical properties of the model. Subsequently, the model is calibrated for 60 countries. Numerical experiments show that the informal sector slows down the infrastructure accumulation process while helping low skilled to escape from extreme poverty. A quantitative assessment of a bench- mark restrictive scal policy suggests that, in the long run, an increase in the tax rate would be benecial for high skilled individuals without worsening the welfare of low skilled individuals. The results are robust to the brain drain mechanism accounted.In the second chapter sovereign debt crisis are the object of the study. Initially, a brief review of the literature on sovereign debt crisis is provided, in light of the OLG model developed in the second part. I assume that the government default choice leads to a permanent drop in productivity and as a result, the government's choice is driven by a cost-benet analysis. It has been proved that when the economy starts with an initial level of capital lower than a threshold, the government nds it protable to bankrupt. As a consequence, the model predicts that economies with the same level of outstanding debt but dierent initial capital levels can have dierent default behaviors suggesting that developing countries may be credit constrained.