The study examined whether charter schools have higher growth in student achievement than traditional public schools.
The study analyzed data on 79 charter schools and 593 traditional public elementary, middle, and high schools in the Los Angeles Unified School District from 2005-06 to 2006-07.
School-level academic achievement was measured using the Academic Performance Index (API) created by the California Department of Education. The API is a composite measure of how well a school’s students perform on standardized tests.
The study measured the effect of charter schools by comparing the change in the API from 2005-06 to 2006-07 for charter schools to the change for their matched comparison schools during the same period.
What did the study authors report?
The study found that the API in charter schools
increased more from 2005-06 to 2006-07 than it did
in matched comparison traditional schools.
However, the WWC does not consider these results conclusive because there is no evidence that the schools were initially equivalent. The reported differences might reflect differences in the types of students who attend charter schools rather than the effect of these schools on student achievement.