Ignoring the Evidence Doesn’t Make It Disappear

If a study shows the benefits of school choice, but you don’t read it, does it really exist?

Apparently not, at least according to Americans United for Separation of Church and State (AU), an organization ideologically committed to opposing school choice. In a blog post today, AU makes this demonstrably false claim:

For example, voucher boosters often assert that students who receive vouch­ers excel academically in private schools. In fact, no objective study has shown this to be the case. Several studies show that voucher students perform the same or worse academically as their peers in public schools.

In reality, there have been 13 randomized controlled gold standard studies of the effect of school choice policies, all but one of which found a statistically significant positive impact. One study found no discernible impact and none found any harm. For AU’s benefit, here is a sampling:

  • William G. Howell and Paul E. Peterson, The Education Gap: Vouchers and Urban Schools, Brookings Institution, 2002, revised 2006. – After two years, African-American voucher students had combined reading and math scores 6.5 percentile points higher than the control group.
  • Jay P. Greene, “Vouchers in Charlotte,” Education Next, Summer 2001. – After one year, voucher students had combined reading and math scores 6 percentile points higher than the control group.
  • Jay P. Greene, Paul E. Peterson, and Jiangtao Du, “School Choice in Milwaukee: A Randomized Experiment,” in Learning From School Choice, ed. Paul Peterson and Bryan Hassel, Brookings Institution, 1998, pp. 335-56. – After four years, voucher students had reading scores 6 Normal Curve Equivalent (NCE) points higher than the control group, and math scores 11 points higher. NCE points are similar to percentile points.

None of these findings are earth shattering, but each study found a statistically significant positive outcome overall or for certain subgroups, particularly low-income African-Americans who are currently the most choice-deprived. Moreover, these studies were conducted by experienced researchers at some of the most widely respected academic and research institutions in the world, including Harvard, Princeton, the University of Chicago, and the Brookings Institution.

In another blog post, AU does point to the one gold standard study that found a null result, a reexamination of the Peterson/Howell study of New York’s private scholarship program. However, AU never mentions that this reexamination employed unorthodox methods and classifications, or that a further reexamination of the data by other researchers at Harvard and the Cleveland Clinic Foundation confirmed the initial findings.

The AU staff can continue to close their eyes and stick their fingers in their ears, but they should stop making the false assertion that there is “no evidence” that students benefit from school choice.