The question of whether there is a growing disparity between rich and poor in the world is heatedly debated by critics and proponents of capitalism. A main point of contention is the grounds on which this disparity is measured: whether between developed and developing countries, between rich and poor people within a country, or between rich and poor people across the world. Professor Xavier Sala-i-Martin, whose main area of focus is economic growth and income inequality, has garnered attention for his assertion that poverty has declined significantly in the past two decades among individuals worldwide who earn less than $1 a day. Despite a growing disparity between and within nations, and despite population growth, the average income of individuals worldwide increased because of the increase in the incomes of people in the fastest growing countries like China and India. His findings have been cited in publications like The Economist and The New York Times. The author of a seminal text book with Robert Barro, Economic Growth, he has served as an advisor for the World Economic Forum, the World Bank, the International Monetary Fund and also as the President of the Economic Commission for the Futbol Club Barcelona.

Robert J. Barro and Xavier Sala-i-Martin, Economic Growth, 2nd edition. MIT Press, 2003.