The results from Stanford University’s brand new study of charter public schools in Michigan are impressive: 42 percent of charter schools bested conventional schools in math achievement gains and 35 percent did the same in reading. Only 2 percent of charters did worse in reading and only 6 percent did worse in math.

It’s hard to call those results anything but a smashing success. But critics of charter schools might try to downplay these results and cherry-pick a few negative results. They might question the study’s methodology, too.

Doug Pratt, director of public affairs for the Michigan Education Association, did just that in article about this new study at Michigan Radio.

Pratt and other charter school critics, however, should remember this new study’s methodology is the very same one used in a 2009 study by the same Stanford researchers that charter school critics routinely cite. That study, which did not include any data from Michigan, found that only 17 percent of charters were doing better than conventional schools and 37 percent were doing worse, on average.

The MEA references the findings from Stanford’s 2009 study on a Web page titled, “Suggested Reading: Credible Research on Education Policy Issues.” Similarly, the American Federation of Teachers-Michigan, the second largest teachers union in the state, cites the same study in a 2011 press release, calling it “the most rigorous evaluation of charter school performance.”

It’s not just teachers unions citing this study, however. Gary Miron, a professor at Western Michigan University who spoke out against lifting the cap on Michigan charter schools, referenced the 2009 Stanford study in his legislative testimony. He also co-authored a review of that study for the union-funded National Education Policy Center and called it a “high-quality charter school report” whose “analyses are largely sound.”

Back in 2011, Vickie Markavitch, the superintendent of Oakland Schools, said that there was “very credible data collected by unbiased entities like Stanford University” about the performance of charter schools. She then cited the findings for the 2009 Stanford study.

Michael Rice, superintendent of Kalamazoo Public Schools, gave every member of the Senate Education Committee in 2011 a copy of the 2009 Stanford study and used it as a key point in his testimony against lifting the cap on charter schools in Michigan.

Regardless of how critics attempt to spin the results, there’s no getting around the fact that on the whole there’s a lot to celebrate about Michigan’s nearly 20-year-old charter school experiment. Thousands of students are making greater learning gains because of the hard work others have done to create high-performing charter schools.