http://www.wpri.org/blog/?p=2203

The Legislative Audit Bureau’s (LAB) review of the final year of the state-authorized five year longitudinal study of the Milwaukee Parental Choice Program (MPCP) is once again bringing the never-ending debate on the efficacy of school choice into the public discourse.
At issue is the LAB’s conclusion that statistically significant test score gains for MPCP pupils in the final year of the study may be in part attributed to the introduction of universal Wisconsin Knowledge and Concepts Exam (WKCE) testing for all MPCP pupils. There is research showing mandatory testing can create a bump in test scores. Hence, LAB states the SCDP finding on reading gains is not conclusive.
The LAB analysis is news only if you did not read the School Choice Demonstration Project (SCDP) studies when they were released earlier this year. The SCDP states clearly: “There is some evidence that the larger achievement growth of the MPCP students that we observe is attributable to the introduction of the accountability policy.” In other words, after five years we know MPCP and MPS students experience similar gains in math scores, and statistically significant gains in reading scores that may or may not be caused by the change in testing policy.
Some perspective. Even statistically significant gains are not necessarily all that substantively significant. A slightly higher reading score is not going to make or break the future of a child. It is important to understand what the SCDP study actually set out to accomplish. It was a program evaluation designed to determine how the MPCP impacted Milwaukee students. Accordingly, over the course of the study the public learned an almost overwhelming amount about a program that was once criticized for being understudied. The public now knows: