Martin West and Ludger Woessmann have published a fascinating study in the winter edition of Education Next. Its conclusion--that there is a positive correlation between the prevalence of private schools and high test scores--is something that is widely argued but not so widely proven. West and Woessmann compared PISA scores from 2003 with the number of private schools in 29 countries to find that,
a 10 percent increase in enrollment in private schools improves PISA math test scores by more than 9 percent of a standard deviation, nearly equal to a half of a year's worth of learning. For science and reading, a 10 percent increase in private school enrollment generates an improvement of more than 5 percent of a standard deviation--more than one-fifth of a grade-level. And in educational spending, a 10 percent increase in the private school enrollment leads to a $3,209 reduction in spending per student--on average, more than 5 percent of the total education spending per student through age 15 for OECD countries.
The part, however, that caught my eye was how they controlled for the causes of private school proliferation. They recognized that a country with a high average income or commitment to education would result in more private schools. On the other hand, a school with very poor quality public schools might increase the demand for private alternatives. So, to eliminate these potential effects, they used a totally unrelated number: the Catholic population of the country in the year 1900. Perhaps our readers will disagree but I thought it was a rather innovative solution. Since the Catholic Church founded many Catholic schools during the turn of the century upswing of public education for reasons totally unrelated to current student achievement, West and Woessmann could isolate the effects of private school competition on student achievement and on per-pupil expenditure. You can read the whole study, here.
We've also written about Catholic schools--and their crucial role in American urban education.
