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α: calibrated so average coauthorship-adjusted count equals average raw count
From 1917 to 2012, donations by high-income households in the USA have moved inversely with income inequality. This association contradicts historical narratives and prevailing theory, both of which that imply that high-income households donate rising income shares when inequality increases. The negative correlation holds both unconditionally and after conditioning on other explanatory variables, at both the national and US state levels. Low payout ratios of foundations and endowed charities, combined with this observed relationship, imply that differences in charitable giving will tend to entrench, not reduce, inequality across places over time.