Inequality between world citizens used to be determined in equal measures by class and location. New research, however, reveals that people's fortunes are being dictated primarily by where they live. As a result, economic migration has become the key way for individuals from developing countries to improve their economic standing. And governments will not be able to alleviate the pressure of migration on their societies until global inequality is reduced.

Branko Milanovic, of the University of Maryland, examines the differences in income between countries and concludes that a key priority for policymakers should be aid and support for developing countries. 'Not only is the overall inequality between world citizens greater in the early 21st century than it was more than a century and a half ago, but its composition has entirely changed; from being an inequality determined in equal measures by class and location, it has become preponderantly an inequality determined by location only' finds the report. 'Analysis of incomes across countries for different members of the population reveals a wide gap between the underprivileged in wealthy societies and less wealthy countries. This fact is of great political and economic significance. Individuals can now make large gains from migrating to wealthier countries.'

People tend to compare their personal financial situation to that of their neighbors, coworkers, or friends, based on the homes they live in or the possessions they have. Economists usually use household surveys to measure income inequality.