The National Center for Education Statistics has a new report that is of some interest. Previously readers of Give Up Blog have heard me bitch about how useless the NCES statistics are. Simply, they tend to aggregate such large groups that the data ends up being worthless, the data simply aren't useful for identifying problems as data for the entire nation ends up averaging out anything interesting.

However, this new report is a little bit different. In this case they specifically studied how individual groups of kids, sorted by socioeconomic background performed in different educational systems. Private vs Public, and different religious schools were compared. Much to the chagrin of advocates of voucher programs the data seem to indicate that when you normalize to background, kids perform almost equally well between private and public schools, and when you compare religious schools, those in conservative Christian schools do not do as well. Simply put, kids in private schools do better only because they're drawing from a rich, educated population, not because the schools are inherently better.

In grades 4 and 8 for both reading and mathematics, students in private schools achieved at higher levels than students in public schools. The average difference in school means ranged from almost 8 points for grade 4 mathematics, to about 18 points for grade 8 reading. The average differences were all statistically significant. Adjusting the comparisons for student characteristics resulted in reductions in all four average differences of approximately 11 to 14 points. Based on adjusted school means, the average for public schools was significantly higher than the average for private schools for grade 4 mathematics, while the average for private schools was significantly higher than the average for public schools for grade 8 reading. The average differences in adjusted school means for both grade 4 reading and grade 8 mathematics were not significantly different from zero.

Comparisons were also carried out with subsets of private schools categorized by sectarian affiliation. After adjusting for student characteristics, raw score average differences were reduced by about 11 to 15 points. In grade 4, Catholic and Lutheran schools were each compared to public schools. For both reading and mathematics, the results were generally similar to those based on all private schools. In grade 8, Catholic, Lutheran, and Conservative Christian schools were each compared to public schools. For Catholic and Lutheran schools for both reading and mathematics, the results were again similar to those based on all private schools. For Conservative Christian schools, the average adjusted school mean in reading was not significantly different from that of public schools. In mathematics, the average adjusted school mean for Conservative Christian schools was significantly lower than that of public schools.

So, to sum up, there isn't a large difference between public and private schools, except between public and private schools and conservative Christian schools which apparently aren't as good at math. Maybe because they confuse the kids by teaching them that the world is only 6,000 years old. That might alter their ability to understand numbers correctly.