We appreciate Richard Kahlenberg’s thoughtful response to our article on attrition, replacement, and peer effects in KIPP middle schools.
Our study did address all three ways in which peer influences might make a difference in KIPP’s success, but reached its clearest conclusions about the effects of student attrition and replacement patterns. The headline of the press release has been changed to clarify this.
We found that attrition and replacement patterns could not explain most of KIPP’s positive effects on student achievement, because (a) early attrition patterns at KIPP schools are similar to those at nearby district middle schools; and (b) KIPP schools have large achievement effects in the first year of students’ enrollment, before replacement patterns could have any effects.
We also found that most students entering KIPP were not high achievers prior to entry.
As we acknowledge in the paper, our study did not have data on factors such as student and parent motivation. We agree that KIPP students might benefit from being in a school that includes highly motivated children and families.
– Ira Nichols-Barrer, Brian P. Gill, Philip Gleason and Christina Clark Tuttle
Ira Nichols-Barrer is a researcher at Mathematica Policy Research, Inc., where Brian Gill and Philip Gleason are senior fellows and Christina Clark Tuttle is also a senior researcher.