Nearly 90 percent of charter elementary schools serve a smaller portion of students considered “at risk” than their neighboring traditional public schools, according to a new analysis by the District of Columbia’s Office of Revenue Analysis.

The analysis, posted on the District, Measured blog, found that 47 out of 53 public charter elementary schools (or elementary-middle school campuses) last year enrolled a smaller share of at-risk students than the traditional school whose attendance zone they were located in.

The analysis adds a new perspective to ongoing debates about whether charter schools and traditional schools serve comparable populations.

Students considered “at risk of academic failure” — a new category being used in the District — include those who are in foster care or homeless, who are receiving welfare benefits or food stamps, or who are performing at least a year behind in high school. The D.C. Council has approved extra funding for these students, because they have greater needs and are considered harder to serve.

In a report of its demographic data, the D.C. Public Charter School Board says on its Web site:  “Charter schools serve a student body that is equally or at times more disadvantaged, while outperforming DCPS [D.C. Public Schools].” The Web site notes that D.C. charter schools serve a greater proportion of African American students and comparable percentages of special education students and at-risk students.

While traditional and charter schools serve about the same proportion of at-risk students overall, the students are spread out differently.

The share of at-risk students in traditional schools varies greatly — from 1 to 90 percent. There are very few at-risk students attending elementary schools in affluent neighborhoods in Northwest, where there are no charter schools. There are much higher concentrations of at-risk students in neighborhood schools elsewhere in the city that are more economically challenged and that directly compete with nearby charter schools.

For example, at Noyes Education Campus in Northeast, 63 percent of students were considered at-risk last year. Four charter schools serving similar grades in its attendance zone had smaller numbers of at-risk students: 62 percent at Mary McLeod Bethune Day; 46 percent at DC Preparatory Edgewood Campus; 14 percent at Lee Montessori; and 11 percent at Inspired Teaching Demonstration School.

Charter schools may attract certain families because of their specific philosophy or instructional approach. And families must apply and gain admission through the city-wide enrollment lottery, which requires a level of motivation and organization.  Neighborhood schools, by right, must enroll any child within its boundaries starting in kindergarten.

Ginger Moored, a fiscal analyst for the city who conducted the analysis, said she was interested in whether relying on a city-wide lottery would increase socio-economic diversity in charter schools, because they can draw from all different neighborhoods. But she found that was not always true.

“Both DCPS and charters have some of the least economically diverse schools in the city—they’re just located in different parts of the city,” she wrote.

The difference in concentrations of at-risk students between charters and DCPS was most pronounced east of the Anacostia River in some of the city’s poorest neighborhoods. Two dozen traditional public schools had concentrations of at-risk students that exceeded 75 percent compared to just one charter school.

You can find interactive maps with school-level information about at-risk populations on the District, Measured Web site.