The Heartland Institute - by Andrew J. Coulson: "A recent analysis of national test score data suggests private schools do a better job than public schools of closing the achievement gap between black and white students as they progress from fourth to 12th grades.
That was true despite the fact that the disproportionately higher dropout rate among African Americans in public schools tends to remove poor performers from the test-taking population of public school seniors.
Closing the achievement gap between black and white students has been one of our nation's overarching goals for half a century. However, there remains a gulf of more than 200 points between the SAT scores of white students and black students, and black children trail their white peers by significant margins on every subject tested by the National Assessment of Educational Progress (NAEP)."
Similarly, in a study comparing graduation rates of all Milwaukee public school students (of all income levels) with those of the low-income participants in the city's private school voucher program, Manhattan Institute Senior Fellow Jay Greene found the voucher students were more than one-and-a-half-times as likely to graduate as public school students.
More remarkable still, Greene found this to be true even when he compared the voucher students with those attending Milwaukee's elite group of academically selective public schools.
This higher graduation rate in private schools is not only a boon in itself; it also casts the private sector achievement gap reductions in an even more favorable light. Dropouts tend to be poor performers academically, so when they leave the test-taking population, the average test scores of the remaining students usually rises.
This dynamic should generally improve the test scores of public high school seniors, which means public schools have an even worse impact on the test score gap than the statistics show."
Read it all for actual statistics and more analysis.