https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4409363/ "The main predictor variable of this study is area racism within DMAs [23]. This previously developed variable was calculated as the proportion of total Internet search queries containing the “N-word” (singular or plural) using Google from 2004–2007. More colloquial forms of the “N-word” (i.e., ending in “-a” or “-as”) were not included given prior analysis of top searches revealing that these versions were used in different contexts compared to searches of the term ending in “-er” or “-ers” [23]. Data on area racism were unavailable for Alaska and small DMAs, resulting in a total of 196 DMAs included in analyses." Apparently it's based simply on searches for "nigger" or "niggers". Completely ignores any other slurs against other races, or actual crime statistics.