Income-based school assignment policy influences diversity, achievement

However, segregation increased much more rapidly in four other large North Carolina school districts that simply dropped race-based strategies and did not attempt to pursue diversity in other ways.

"While we found some decline in the degree of racial diversity associated with Wake County schools after adoption of the socioeconomic plan versus the prior race-based plan, there was significantly less diversity in the school districts that were not using either plan," said William A. Darity Jr., Samuel DuBois Cook Professor of Public Policy in the Sanford School.

In addition, Wake County math and reading scores rose slightly and the achievement gap between black and white students narrowed after the switch. In the four other N.C. districts, scores fell among black students after race-based school assignment stopped.

The research was published online in the journal Urban Education on Nov. 27.

"The main message is, we may not want to give up on using diversity-based policies to achieve integration and address opportunity gaps and achievement gaps," said lead author Monique McMillian. McMillian, an educational psychologist, is an associate professor at Morgan State University in Maryland and an affiliate of Duke University's Research Network on Racial and Ethnic Inequality.

North Carolina school districts stopped using race-based assignment plans in the late 1990s after a series of court cases struck down the practice in various settings around the country.

In 2000, Wake implemented a new assignment policy based on income and achievement, in which no school would consist of more than 40 percent students receiving free or reduced lunch, nor more than 25 percent of students performing below grade level. (In 2010, the Wake County school board voted to stop using an income-based policy. However, income remains a component -- albeit a smaller component -- of the current assignment policy.)

McMillian saw the change as an opportunity to investigate how the different policies affect school integration and student achievement.

She, Darity and their colleagues analyzed data from Wake and four other large N.C. school districts: Charlotte-Mecklenburg, Cumberland County, Guilford County and Winston-Salem/Forsyth County. Like Wake, these school districts had previously used race-based assignment policies, but unlike Wake, they switched to a combination of neighborhood schools and school choice.

The researchers analyzed data from 1992 to 2009, including demographic data about schools and students, and 10 years of end-of-grade test scores for third through eighth graders.

McMillian said the study was largely descriptive. It's not possible, therefore, to say whether the new school assignment policy alone caused Wake's test score gains or reduced the achievement gap between white and black students. Other factors may have contributed as well, such as changes in other district policies or implementation of the No Child Left Behind Act of 2001, she said.

McMillian said the study provides "tentative evidence that income-based assignment policies improve achievement and increase diversity."