June 3, 2008
For immediate release
Professor John Yun of UC Santa Barbara’s The Gevirtz School has reviewed a recent report that claimed a Florida program providing vouchers for special education students was effective; Yun claims the report offered vague and flawed statistical analyses. Yun concludes that the Manhattan Institute report offers policymakers little guidance: “Any attempt to use this report for decision-making or policy evaluation, prior to validation using different methods and more robust approaches, should be viewed with extreme skepticism.”
The Manhattan Institute for Policy Research article “The Effect of Special Education Vouchers on Public School Achievement: Evidence from Florida’s McKay Scholarship Program” was written by Jay P. Greene and Marcus Winters. Professor Yun reviewed the study for the Think Tank Review Project.
Florida’s McKay Scholarship Program provides vouchers for special education students to attend private schools. The scholarship program is open to any Florida student classified as having a learning disability; as of the 2006-2007 school year, about 4.5% of Florida’s special education students received these vouchers. The Manhattan Institute analysis appears to cover an earlier period, from school years 2000-2001 through 2004-2005, during which time the program enrolled fewer students.
The Manhattan Institute report is based on statistical analyses that, its authors conclude, shows that the McKay program spurred public schools to improve achievement for those special education students who remained in public schools during that time. The report presents relatively small effect sizes (a small competition benefit), but asserts that these results are probably understated.
Yun’s review finds the statistical evidence weak. Among his criticisms are the following:
In reality, Yun points out, “the number of voucher recipients was quite modest until nearly halfway through the sampled time period. In order for the hypothesized competitive effects to have caused improvements in nearby public schools, those schools would have had to almost immediately receive the signal that special education students were leaving their schools and then adjust their practices accordingly, with the effects of these changes then very quickly having an impact on test scores. Such a series of events seems unlikely.”
Yun’s article can be read on-line.
[John Yun is available for interviews; contact George Yatchisin at 805 893 5789]
– end –