My colleague at the University of Arkansas, Patrick Wolf, along with John Witte at the University of Wisconsin and a team of researchers have released their final round of reports on the Milwaukee school choice program. You can read the press release here and find the full set of reports here.
They find that access to a private school with a voucher in Milwaukee significantly increases the probability that students will graduate from high school:
“Our clearest positive finding is that the Choice Program boosts the rates at which students graduate from high school, enroll in a four-year college, and persist in college,” said John Witte, professor of political science and public affairs at the University of Wisconsin-Madison. “Since educational attainment is linked to positive life outcomes such as higher lifetime earnings and lower rates of incarceration, this is a very encouraging result of the program.”
They also find that “when similar students in the voucher program and in Milwaukee Public Schools were compared, the achievement growth of students in the voucher program was higher in reading but similar in math.” Unfortunately, the testing conditions changed during the study because the private school testing went from being low stakes to high stakes, making it difficult to draw strong conclusions about the effects of the program on test scores.
In addition, it should be remembered that the design of the Milwaukee study is a matched comparison, which is less rigorous than random-assignment. The more convincing random-assignment analyses are significant and positive in 9 of the 10 that have been conducted, with the tenth having null effects. You can find a summary and links to all of them here.
Perhaps the most interesting part of the new Milwaukee results is the report on special education rates in the choice program. As it turns out, Wisconsin’s Department of Public Instruction grossly under-stated the percentage of students in the choice program who have disabilities. Some reporters and policymakers act as if the Department of Public Instruction’s reports are reliable and insightful because they are a government agency, while the reports of university professors are distorted and misleading. Read this report on special education rates and I think you’ll learn a lot about how politically biased government agencies like the Department of Public Instruction can be.
Jay P. Greene's Blog 
BOOOOOOOOOOOOOOOOOOOOOOM!!!!!!!!!!!
Three simple words — “compared to what” — frame how a reporter could understand the basic research issues central to the latest SCDP reports. So, one would not portray test scores for dissimilar groups of students and claim it is a “comparison.” Nor would one use test results at individual schools to rank how the schools are performing (absent knowledge that the students at all the schools are similar). Nor would one use results from a single year, as opposed to a longitudinal approach, to draw any conclusions about program effects. These are among the basic errors reflected in the Milwaukee Journal Sentinel’s coverage of the SCDP research. It is left to SCDP scholars and more responsible reporters beyond Milwaukee to help set the record straight. Pat Wolf and his colleagues have done exceptional work. It deserves to be understood.
[…] to Dr. Jay Greene, “perhaps the most interesting part of the new Milwaukee results” is the steep discrepancy in how many special-needs students are being served by the voucher […]
The Milwaukee Parental Choice Program simply allows students to attend private sectarian or nonsectarian schools at no cost. I’m having difficulty understanding how the Choice Program boosts the likelihood that students will graduate from high school, enroll in a four year college, and persist. I have difficulty understanding that since some private schools probably perform well, but others probably not so well.
Here are some of the possible reasons choice could boost educational outcomes (note that these are not mutually exclusive, nor do all of them need to be present):
1) Multiple models. Every child is different and has different educational needs. Choice allows for the introduction of different educational approaches, so that students aren’t stuck wtih the failed one-size-fits-all approach of the last century.
2) Sorting. Different schools will serve different students better for reasons other than the “model” issue described above. Choice allows students to find the school that serves them best.
3) Competition. Schools that perform well will attract and retain students, creating a healthy incentive to perform and giving administrators the credibility to impose needed reforms in failing schools (i.e. people get on board for reform when the success of the school is clearly at stake, and only choice provides that).
4) Finances. In most cases, school choice improves the financial picture for affected public schools, because they lose all the expenses associated with students who leave for private schools, but they don’t lose all the funding. Thus public schools have more dollars per student. (This is not the case in Milwaukee but I thought I’d throw it in for completeness.)
5) Family support. A school where parents have “bought in” by choosing to be there will get more family support and have a tighter fit between parental authority and teacher authority. This applies in public schools where parents *choose* to stay just as much as in private schools where parents choose to opt in.
6) Culture. Schools that exist because people choose to be there rather than because people were forced to be there will develop a cultural solidarity that enables them to perform better in countless intangible ways.
7) And lots more reasons I don’t have time to type in!
Now, you’re right that the impact of existing choice programs is not revolutionary. That’s because the programs are not designed in such a way as to permit them to have revolutionary effects. They are modest programs that have a moderate impact. But the impact is clearly there, as the consensus in the empirical research shows.
An interesting finding from the SCDP results relates to the recent requirement that voucher students take the same criterion-referenced test administered in the Milwaukee Public Schools.
For a variety of reasons that don’t merit elaboration here, I opposed this. Vigorously.
Yet, this requirement appears to be associated with a gain in test scores shown by voucher students.
I want to acknowledge this potential benefit and my apparent error.
Of much greater importance is the range of findings from the SCDP’s 5-year research project. This poses an interesting test for those who claim that honest research matters. I still cling to that view.