Study: Public schools outperform private schools in student achievement
May 10, 2005
A new study turns conventional wisdom on its head about the academic performance of public and private school students, finding that public school students significantly outperform their private school peers in math after controlling for demographic and socioeconomic factors. The overall achievement advantage held by private schools is attributed to the stark differences in student body demographics and socioeconomic status between public and private schools, according to the study by researchers at the University of Illinois at Urbana-Champaign. The researchers examined 4th graders’ and 8th graders’ math scores from the 2000 National Assessment of Educational Progress (NAEP).
Key findings
1. When accounting for demographic / SES (socioeconomic status) differences among public and private school students, public school students performed “significantly better” than Catholic and other private school students.
2. When the researchers looked at public and private school students’ performance across four SES quartiles (low SES, low-mid SES, mid-high SES and high SES), public school students outperformed private school students in each one. Public school 4th graders’ average scores were 6-7 points higher within each quartile, and public school 8th graders’ average scores were 1-9 points higher.
3. Public schools enroll “much higher” percentages of African-American, Hispanic, lower-SES students, and students with disabilities than do Catholic and other private schools. At each grade level, less than 40 percent of the public schools were high SES (meaning their SES was above the median for all schools) while more than 80 percent of private schools were of high SES.
4. While the average overall math scores of private school students was “significantly higher” than that of public school students, the advantage is explained by the demographic and socioeconomic differences of the student bodies.
5. The researchers found that SES-related achievement gaps were smaller in Catholic and other private schools among 4th graders than in public schools, and the achievement gap for 8th grade Hispanic students was smaller in Catholic schools than in public schools.
6. Most of the research that has led to common assumptions that private schools are more effective at raising student achievement than public schools is three decades-old and was largely limited to high school students.
For more information on this study, go to the Phi Delta Kappan May 2005 issue here, or read the full study posted by the National Center for the Study of Privatization in Education here. More also from the University of Illinois at Urbana-Champaign here.