Ecological Fallacy

Identified by sociologist William S. Robinson in his 1950 paper analyzing 1930 census data. Robinson demonstrated striking discrepancies between state-level and individual-level correlations: the correlation between percent black and percent illiteracy was 0.77 at the state level but only 0.20 at the individual level. Though Robinson used the term "ecological correlation," Selvin coined "ecological fallacy" in 1958. Robinson's paper has been cited over 1,150 times across social sciences, public health, and biomedical research.