Friedman Voucher study not quite what it seems

Well, if you took a statistics class, you probably heard something along the lines of: "Don't go into a study with your conclusions already drawn."
Not a big surprise that an institution which calls itself the "Friedman Foundation for Educational Choice" might sponsor a study showing that vouchers improve schools, therefore. They do have a conclusion right there in their name! The study, released in February and covered fairly extensively at the time, was presented as a comprehensive study of previous research on the effect of vouchers on public schools, and concluded that they do the public schools only good. The foundation said that this study proved that vouchers do not, as previously presented, cream the good students off of public schools, and that they only improve public schools.
A closer look at the Friedman Foundation's report by the Think Tank Review Project by Professor Christopher Lubienski of the University of Illinois has found the Foundation's study has some important holes; to wit:

• a.. While it claims to reflect "all available empirical studies on how vouchers affect academic achievement in public schools," the majority of the studies cited in the report were produced by explicitly pro-voucher advocacy organizations, and almost all did not undergo peer review.
• b.. Lubienski describes a study that was misrepresented in the report. The report summarizes only the first part of the study, which merely replicated other research. But it was in the second part that the researchers explained why a different approach would be more rigorous. That more rigorous approach found no improvement in public schools from voucher programs; it was dismissed by the Friedman report as "unnecessary."
• c.. The report makes no serious attempt, where vouchers are found to be associated with improved public school performance, to test for alternative explanations, as would be required in credible research. Instead, it relies on a "black box" analysis that blindly attributes improved achievement to the presence of a voucher policy.

In other words, this wasn't much of a study, dismissing pieces of research that didn't agree with their forgone conclusions, and not testing alternative explanations for end results. Not good research practices.