Review of The Productivity of Public Charter Schools

This report claims superiority of charter schools in producing achievement per dollar invested. The findings are cast as cost-effectiveness ratios, where effects are measured by National Assessment of Educational Progress (NAEP) points and costs are measured as “revenues received.” The report concludes that charter schools deliver an additional 17 NAEP points per $1000 in math and 16 points per $1000 in reading. All analyses are undertaken with data for 21 states and the District of Columbia. Because an earlier review by Baker pointed to serious flaws in the “cost” part of the ratio, this review will focus on achievement. The effects of charter versus traditional public schools are estimated by comparing state averages of both sectors without attempting to equate them on demographic variables like poverty (free lunch eligibility) or special-needs status. Not reported is the fact that the demographic differences between the two sectors are highly correlated with the estimates of differential effects; the sector with the higher percentage of poor pupils scores lower on the NAEP test. This failure alone renders the report and its recommendations indefensible. Furthermore, the assessment of expenditures in the two sectors rests on non-comparable data across states and questionable data within states. These weaknesses leave little evidence on which to base any valid conclusions. Reports of this type can only be viewed as advocacy research, in large part because they fail to reconcile their findings with the extensive literature of contrary findings.