Are public schools better than private?

The Atlantic has a short interview with University of Illinois - Urbana-Champaign professors Sarah Theule Lubienski, and her husband Christopher A. Lubienski: “a new book argues that public schools are actually academically superior”.

I don’t have the book (The Public School Advantage- Why Public Schools Outperform Private Schools to be published in November 2013), but the authors wrote a 2006 paper that seems to conclude the same thing. Essentially they use a large dataset to argue that, while private schools do outperform public schools overall, the advantage disappears when you account for demographics of the students.

This would indeed be interesting if it were true. But a quick look at the paper makes me wonder about some obvious mistakes in methodology behind the  headline-grabbing “conclusion”.

• 150K public students (96%) vs. 6500 private students (4%)
• 2K Catholic, 2K charter, 1K “Christian”
• Of 6,000 schools overall, only 150 are “other private”.

Since almost all of their data from private schools is from religious schools (mostly Catholic), shouldn’t that be the headline? This is NOT comparing your local school with the $20K/year highly-selective boarding school that many people imagine when they think “private school”.  As the study itself points out, there are many reasons parents might shell out extra money to send their kids to a school, but religion is a big one that, if anything, would trump "academics” in a lot of cases.

As always, my conclusion is to wonder how useful it is to know in aggregate whether something as variable as education is better done one way or another. What matters is what’s good for your kid. Trying to make a generalization about education systems based on a database of thousands of schools is like trying to predict the value of your home by looking at trends in US real estate. Who cares?