Why Public Schools Outperform Private Schools

Christopher and Sarah Lubienski's newest book, The Public School Advantage: Why Public Schools Outperform Private School, reaches some counter-intuitive and significant conclusions. First, contrary to the assumptions of many and some older research, private schools are not outperforming public schools.  To the contrary, public schools are outperforming.  There seems to be some nuance not fully explored in this global finding, such as whether some subsets like secular academic private schools are outperforming public schools.  Those questions were not answered because the data insufficient to draw firm conclusions comparing private schools amongst themselves.  But the overall finding regarding private versus public public schools is clear: while the raw achievement scores in some private schools may be higher than those in public schools, it is only because they disproportionately enroll wealthier and other demographically privileged groups of students.  When those demographic factors are controlled, there is no "value-added" benefit of private school.  In fact, there is value lost.

This leads to the second question: why are private schools underperforming?  The Lubienski's conclusion is that:

It appears that there is a danger in the autonomy that private schools have. The teachers aren’t required to be certified, there is less professional development happening, they’re not held accountable to the same kinds of state curriculum standards and tests. And so when we look at scores on those things it just makes sense that the schools who are hiring teachers who are certified and have been educated in a way that helps them understand all the current educational reforms and the research on learning—that those teachers would be more effective. Particularly more effective at educating students on the state standards...So, yeah, the autonomy of private schools may not be all it’s cracked up to be.

These findings are obviously of crucial importance in the debate over vouchers, as the premises behind vouchers are at odds with these new findings.  Moreover, if one drops  the assumed academic advantage of going to private school through vouchers, the remaining basis/justification seems more aligned with supporting parents religious motivations.  The Court was able to dodge this problem in Zelman v. Simmons-Harris, but studies like this would suggest we revisit that question.