In their new study, “Racial and Economic Diversity in North Carolina’s Schools: An Update,”  Charles Clotfelter, Helen Ladd, and Jacob Vigdor of the Sanford School of Public Policy at Duke University examine the racial and socioeconomic mix of students within districts, schools, and classrooms in North Carolina.

Here is a summary of their findings:

1. Statewide, school segregation had been increasing prior to 2005/06, but has since leveled off.
2. Even in a climate where busing for racial balance is off the table, district policies matter.
3. Few of North Carolina’s charter schools serve a racially balanced student body.
4. The growth of North Carolina’s Hispanic population has literally made school integration more than a black-white issue.
5. Imbalance by economic status has increased even as racial imbalance has held steady.
6. Schools serving a high proportion of nonwhite or low-income students face challenges in recruiting and retaining teachers with strong credentials.

These findings make me wonder whether socioeconomic status is a reliable proxy for race.  Proponents of busing often use socioeconomic status (measured in Free and Reduced Priced Lunch eligibility) to achieve their goal of creating “racially integrated” or (in the case of Wake County) “healthy” schools.  But Clotfelter et al. show that measures of socioeconomic and racial balance are going in different directions.  I do not recall reading anything about the relationship between the two measures in the study.

Of course, there is an obligatory jab at charter schools, which must use a random lottery to award seats to students.  A district may be able to design assignment areas that achieve a certain racial or socioeconomic mix, but charter schools cannot.

Finally, the study does not examine outcomes.  In other words, they do not consider whether changes in the racial and socioeconomic composition of schools has any relationship to student achievement.  They present evidence that there may be differences in teacher quality, but we never know whether these differences have a significant impact on academic outcomes.