Even before the state Supreme Court ruled them unconstitutional, charter schools were a topic that engendered heated debate (at least here in Washington; charter schools are perfectly constitutional in 41 other states). Therefore, data, backed up by solid research, provides a welcome relief from the rhetoric.

For some years now the Center for Research on Education Outcomes (CREDO) at Stanford University has been studying charter school performance. In 2009, 2013 and 2015, CREDO issued comprehensive reports on charter schools and compared them to regular public schools.

The 2009 National Charter School Study, which covered 15 states and the District of Columbia, had a tough assessment of charters:

“[A] decent fraction of charter schools, 17 percent, provide superior education opportunities for their students. Nearly half of the charter schools nationwide have results that are no different from the local public school options and over a third, 37 percent, deliver learning results that are significantly worse that their student would have realized had they remained in traditional public schools.”

It wasn’t all bad, though, with CREDO noting:

“[T]he academic success of students in charter schools was affected by the individual state policy environment.  States with caps limiting the number of charter schools reported significantly lower academic results than states without caps limiting charter growth. States that have the presence of multiple charter school authorizers also reported lower academic results than states with fewer authorizers in place. Finally, states with charter legislation allowing for appeals of previously denied charter school applications saw a small but significant increase in student performance.”

And:

“For students that are low income, charter schools had a larger and more positive effect than for similar students in traditional public schools. English Language Learner students also reported significantly better gains in charter schools, while special education students showed similar results to their traditional public school peers.”

In 2013, CREDO issued a second national study, based on charter schools in 24 states, the District of Columbia and New York City. It showed some improvement:

“[Twenty-five] percent [of charter schools] have significantly stronger learning gains in reading than their traditional school counterparts, while 56 percent showed no significant difference and 19 percent of charter schools have significantly weaker learning gains. In mathematics, 29 percent of charter schools showed student learning gains that were significantly stronger than their traditional public school peers’, while 40 percent were not significantly different and 31 percent were significantly weaker.”

Again, low-income and minority students fared quite well in charter schools:

“Students in poverty, black students, and those who are English language learners (ELL) gain significantly more days of learning each year in both reading and math compared to their traditional public school peers. Performance differences between charter school students and their traditional public school peers were especially strong among black and Hispanic students in poverty and Hispanic students who are ELL in both reading and math.”

CREDO’s most recent work, the 2015 Urban Charter School Study/ Report on 41 Regions, focused specifically on urban charter schools “because these are communities where students have faced significant education challenges and are in great need of effective approaches to achieve academic success,” according to CREDO director Dr. Margaret Raymond.

Students in urban charter schools showed much more dramatic benefits:

“Across 41 regions, urban charter schools on average achieve significantly greater student success in both math and reading, which amounts to 40 additional days of learning growth in math and 28 days of additional growth in reading. Compared to the national profile of charter school performance, urban charters produce more positive results. CREDO’s National Charter School Study results in 2013 found that charter schools provided seven additional days of learning per year in reading and no significant difference in math.”

No surprise, then, that most of Washington’s current charter schools are in urban areas.

In future posts we’ll discuss reactions to the CREDO studies and further explore the topic of how charter schools might help close the educational achievement gap.