On Charter School Accomplishment
CREDO is the best national quasi-experimental data source we have, and its methodology holds up well in comparisons with experimental data.
To the extent you’re suspicious of CREDO or of quasi-experimental design, Rand also did a national study on charters that looked exclusively at experimental studies. The authors found:
“Consistent with many previous studies that have focused on broad sets of charter schools, we found no evidence that, on average, attending charter schools had a positive impact on student achievement. The estimated impact of attending the average charter school in the study was negative but not statistically signicant after adjusting for the multiple hypotheses tested. However, the average impact of attending charter schools in large urban areas or those serving lower achieving or more disadvantaged students was large and positive.”
