The analysts created their own measurement index for their comparison, using 2013-14 NCES Data for student enrollment and demographic information and 2010 data from the National Historic Geographic Information System (NHGIS) to determine neighborhood composition. NHGIS data are broken down into small census blocks. For purposes of this study, a school’s neighborhood includes all census blocks within two miles of a school that are also within the same school district. These demographics are then compared to school demographics to determine the “racial imbalance measure.” Each school has a racial imbalance score for white, black, Hispanic, Asian, and other race students.
The analysts determined that, unsurprisingly, U.S. schools typically have similar racial compositions to their surrounding neighborhood. Yet one third of schools were labeled “outliers,” meaning they had significant over- or underrepresentation of one or more race/ethnicity, when compared to other schools in their state. The most common types of outlier schools were those with higher black representation than the surrounding neighborhood and schools with lower white representation.
Charter schools were substantially more likely than district-operated schools to have student bodies significantly different than their neighborhoods. This was true of for white, Hispanic, and black students, but the difference was highest for the latter group: Nationwide, charters were 4.1 percentage points more imbalanced, and three times more likely to be outliers, than district schools when it came to African American pupils.