After re-analyzing the data used by a recent U.S. Department of Education study that found a rough parity in the effects of public and private schools on student achievement, Kennedy School of Government researchers Paul E. Peterson and Elena Llaudet, using what they regard as a preferred methodology, have identified a consistent, statistically significant private school advantage.

Utilizing the same data as the original study but substituting better measures of student characteristics, the Harvard researchers find a private school advantage in 11 out of 12 public-private comparisons. In 8th-grade math, the private school advantage varies between 3 and 7 test points; in reading, it varies between 9 and 13 points. Among 4th graders, in math, parity is observed in one model, but private schools outperform public schools by 2 to 4 points in the other two models; in 4th-grade reading, private schools have an advantage that ranges from 6 to 10 points. All but one of the differences are statistically significant. (See table below for results as well as detailed breakdowns for Catholic, Lutheran, Evangelical Protestant and other private schools.)

Read the full report, here.