The results of this initial analysis reveal that students in charter schools, on average, make annual gains that are 0.06 standard deviations less in reading and 0.08 standard deviations less in
math than students in traditional public schools with similar observable characteristics.
A study released earlier this month by Mathematica finds that students attending charter high schools in Florida scored lower on achievement
tests than students in traditional public schools, but years later, the charter students were more likely to have attended at least two years of college and also had higher earnings.
The most careful, comprehensive study of virtual charter schools, from Stanford's Center for Research on Education Outcomes, found that virtual charter students achieved the equivalent of 180 fewer days of learning in math and 72 fewer days of learning in reading
than students in traditional public schools.