Bryan Hassel, Charter School Leadership Council
The short answer to the implied question in this report's title is: not enough but much of what we know is brighter than the New York Times wants you to think. Bryan Hassel of Public Impact looked at 38 studies of charter school achievement that meet certain criteria for timeliness, analytic seriousness, and scope. His report finds that the studies are all over the map, both in their usefulness and their findings. Some have serious methodological shortcomings (especially in looking at aggregated school performance rather than disaggregated student performance). About half, including the infamous AFT study from last August are less-useful snapshots rather than appraisals of performance over time. Of the 21 that do look at data over time, 12 find charters outpacing public school achievement gains generally or for specific at-risk populations, five call it a draw, and three say charters are behind. A murky picture, though on balance encouraging, and we should take to heart Hassel's call for more and better data and analysis of charter school performance. You can find the full report at http://www.charterschoolleadershipcouncil.org/PDF/Paper.pdf.