It includes measures of academic achievement and achievement gaps for school districts and counties, as well as district - level measures of racial and socioeconomic composition, racial and
socioeconomic segregation patterns, and other features of the schooling system.
The strongest correlates of achievement gaps are local racial / ethnic differences in parental income, local average parental education levels, and
patterns of racial / ethnic
segregation, consistent with a theoretical model in which family
socioeconomic factors affect educational opportunity partly though residential and school
segregation patterns.