May 22, 2013
Dominic Slowey
(781) 710-0014


It’s Time to “Lift the Caps on Quality”

A new study conducted by MIT’s School Effectiveness and Inequality Initiative and published by The Boston Foundation and New Schools Venture Fund, shows that Boston charter school students dramatically outperform their peers in other public schools on MCAS, SAT and Advanced Placement tests.

The study, released today, is the latest in a series of analyses demonstrating the remarkable academic success of charter public schools in Massachusetts, and is more evidence that arbitrary caps on charter expansion should be eliminated.

(Study can be found at: See TBF news release:

The state Legislature is considering a bill, filed by Sen. Barry Finegold (D-Andover/Lawrence) and Rep. Russell Holmes (D-Mattapan), which would eliminate the cap on charter public schools in Massachusetts’ lowest-performing school districts. 

About 30 percent of the Commonwealth’s public school students are enrolled in the 29 lowest-performing districts. Even though enrollment caps on charter schools were increased in these districts in 2010, demand has been so great that communities such as Boston, Lawrence and Holyoke already have little or no room for additional charter schools.

The MIT study comes on the heels of a February Stanford University study, which found that Boston charter public schools are doing more to close achievement gaps than any other group of public schools in the country. A 2009 study of Boston charters conducted by Harvard and MIT researchers revealed similarly strong academic results.

The study debunks the myth that charter school success is due to student “selection” practices, comparing the performance of charter students to those who wanted to enroll but were not accepted in enrollment lotteries and remained in district schools. MCAS scores of children who entered charter lotteries and “won” were equivalent to children who entered the lotteries and “lost.” But several years later, Boston charter students improved their scores to rival students from Brookline, one of the top districts in the state.

Highlights of the study:

MCAS: Charter public school attendance increases the likelihood that applicants meet Massachusetts graduation competency standards. A far higher percentage of charter schools students score Proficient (16%) or Advanced (17%) on MCAS.

SAT: The research team found that charter public school students scored more than 100 points higher on the math SAT and 51 points higher on the English SATs, a large and statistically significant result.

Advanced Placement: More than half of charter publics school students take at least one AP test, compared with about a quarter of the students in traditional public schools. Charter students were also more likely to score a 3 or higher on the test, the level at which students typically qualify for college credit. Charter attendance increases the probability of earning a score of 3 by a marginally significant 9.5 percentage points, but generates no significant increase in the likelihood of earning a 4 or 5.

Graduation: Researchers found a slightly lower four-year graduation rate but a slightly higher rate for students taking five or six years to graduate. (Since charter high schools often keep their students for more than four years to ensure they are ready for college, these findings are not surprising.) In neither case, however, were the results statistically significant.

College enrollment: The researchers found that charter attendance increases college enrollment by about six percentage points among four-year graduates, an estimate that grows to 13 points for students who take an extra two years to graduate. The researchers found that charter attendance increased the probability of enrolling in a four-year college by 23 percentage points within two years of graduation, and reduced the likelihood that a student would attend a two-year college by 10 percent.

Charters and special education students: Charter attendance increases the rate at which special education students meet state competency standards markedly, and appears to generate increased human capital for special education students, as evidenced by especially large gains in MCAS and SAT scores. On the SAT, the charter attendance impact was 164 points. The researchers conclude that, “With the exception of Adams Scholarship qualification and a possible delay in high school graduation, special education students seem to get as much or more from charter attendance as does the general applicant population.”

Creaming: The researchers also explored a theory that charters are driving out less desirable students in order to improve scores. First the study counted all students who attended a charter in the charter schools group even if they eventually left the charter program. Researchers also looked at the “peer effect” of charters to see if changes in the charter population during high school strengthened the overall performance of the classes, and found that while charter students were more likely than their peers to change schools, that increased school switching did not appear to lead to further changes in peer composition that might explain the beneficial effects of charter attendance.