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Economic Inequality

Economic inequality refers to the unequal distribution of income, wealth, or consumption among individuals, households, or groups within a population, or between populations across countries and regions. It is most commonly measured using the Gini coefficient, a statistic ranging from 0 (perfect equality, where every unit receives an identical share) to 1 or 100 (perfect inequality, where a single unit receives the entire share), though other measures - including the Palma ratio, top income shares, and wealth-to-income ratios - are also used. The Gini coefficient is the standard measure of income inequality and income distribution within countries, calculated from the Lorenz curve, which graphs cumulative income share against cumulative population share. The term encompasses several analytically distinct concepts - income inequality, wealth inequality, and inequality of opportunity - which are sometimes conflated in public debate. Whether a given level or trend in economic inequality represents a problem requiring correction, a neutral byproduct of a market economy, or in some cases a sign of healthy economic dynamism is contested; see economic-inequality-market-outcome-egalitarian-viewpoint-debate.

Current State of Knowledge

Economic inequality is tracked at multiple levels of analysis, and the distinction between them shapes much of the discussion:

National-level data is compiled by bodies such as the World Bank's Poverty and Inequality Platform and the OECD, drawing primarily on household surveys, with data referring either to income after taxes and benefits or to consumption per capita - measures that are not perfectly comparable, since consumption tends to be more evenly distributed than income. Cross-country comparisons are complicated by differing data collection methods, survey years, and whether pre-tax or post-tax, post-transfer income is used.

Two of the most consequential developments shaping the modern debate are economic globalization - the increased integration of trade, capital, and labor markets across countries - and the shift toward post-industrial, knowledge- and technology-based economies in developed nations. Both are widely credited with reducing between-country inequality (as manufacturing and supply chains shifted to lower-income nations) while their effect on within-country inequality in wealthy nations is disputed; see economic-inequality-globalization-debate. For historical background on the measurement and political salience of economic inequality, see economic-inequality-history.

Consensus Status

There is broad, independently-arrived-at agreement among economists and statistical agencies that the Gini coefficient, despite its limitations, is a valid and standard tool for measuring income and wealth distribution within and across populations. This methodological consensus is distinct from any agreement on the normative significance of a given inequality level, which remains contested; see economic-inequality-measurement-consensus.

Viewpoints

Controversies

Footnotes