(Guest Post by Collin Hitt)
Mathematica released a major study of KIPP charter schools today. KIPP is primarily a middle school network, with schools across the country. The Mathematica study uses a random-assignment research design, making it at least the eleventh such study we now have on charter schools. It found significant gains in math, positive but insignificant gains in reading. So, again, every random assignment study yet conducted on urban charter schools finds positive effects.
The random assignment study was limited to 13 KIPP charter schools in six states. KIPP’s network is much larger than that. So the authors employed a matching technique in order to evaluate the impact of a larger number of KIPP schools: they compared KIPP students to other kids who on paper were nearly identical. Matching techniques are far less rigorous than lottery-based estimates. But, since Mathematica had lottery-based estimates against which they could compare their matching technique estimates, they were able to validate their matched sample of students as a credible comparison group. They found that their random assignment estimates closely tracked their matching estimates, at relevant schools.
So they employed their matching techniques at a larger sample of 41 schools. Mathematica then concluded that after just three years in KIPP, students made gains in math, reading, science and social studies that ranged from 8 to 14 months of additional learning. In the parlance of Matt Ladner, “boom.”