remaining tariffs and other barriers to trade" and "90.1% disagree with the suggestion that the U.S. should restrict employers from outsourcing work to foreign countries." Quoting Harvard economics professor N. Gregory Mankiw, "Few propositions command as much consensus among professional economists as that open world trade increases economic growth and raises living standards." In a survey of leading economists, none disagreed with the notion that "freer trade improves productive efficiency and offers consumers better choices, and in the long run these gains are much larger than any effects on employment." Most economists would agree that although increasing returns to scale might mean that certain industry could settle in a geographical area without any strong economic reason derived from comparative advantage, this is not a reason to argue against free trade because the absolute level of output enjoyed by both "winner" and "loser" will increase with the "winner" gaining more than the "loser" but both gaining more than before in an absolute level. In the book The End of Poverty, Jeffrey Sachs discusses how many factors can affect a country's ability to enter the world market, including government corruption; legal and social disparities based on gender, ethnicity, or caste; diseases such as AIDS and malaria; lack of infrastructure (including transportation, communications, health, and trade); unstable political landscapes; protectionism; and geographic barriers. Jagdish Bhagwati, a former adviser to the U.N. on globalization, holds that, although there are obvious problems with overly rapid development, globalization is a very positive force that lifts countries out of poverty by causing a virtuous economic cycle associated with faster economic growth. However, economic growth does not necessarily mean a reduction in poverty; in fact, the two can coexist. Economic growth is conventionally measured using indicators such as GDP and GNI that do not accurately reflect the growing disparities in wealth. Additionally, Oxfam International argues that poor people are often excluded from globalization-induced opportunities "by a lack of productive assets, weak infrastructure, poor education and ill-health;" effectively leaving these marginalized groups in a poverty trap. Economist Paul Krugman is another staunch supporter of globalization and free trade with a record of disagreeing with many critics of globalization. He argues that many of them lack a basic understanding of comparative advantage and its importance in today's world. The flow of migrants to advanced economies has been claimed to provide a means through which global wages converge. An IMF study