A study that previously found many students in charter schools - American primary or secondary schools that receive public money and may also receive private donations - were not performing as well as those in public schools has discovered that in a few states, charter schools are improving.
The widely cited study by Stanford University researchers at the Centre for Research on Education Outcomes, has been updated. It examined the standardised test results of students enrolled in charter schools in 25 states, including the District of Columbia and New York City. The charter schools' results were compared with those of students with the same demographics and academic profiles in public schools that the charter students would have otherwise attended.
The study, conducted four years ago, showed that only 17 per cent of charter schools managed to raise student maths test scores above those of local public schools.
The new report said that 29 per cent of charter schools performed better in maths than local public schools.
And while the 2009 study found 37 per cent of charter schools were actually providing a worse education than local public schools, that figure declined to 31 per cent in the new report.
"At both ends of the quality curve, we see that the situation is getting better," said Margaret Raymond, the centre's director.
Still, the report is likely to provide fodder for critics of charter schools, which are publicly financed but privately operated. More than two million students attend about 6,000 charter schools in the US.
"Twenty years after the start of the charter school movement, even with all the private energy and public policy cheerleading it has engendered, students in charter schools roughly perform the same as students in the rest of public education - not the leaps and bounds that were promised," Randi Weingarten, the president of the American Federation of Teachers, said in a statement.
The study concluded that charter schools, which are typically given more freedom to design curriculum and hire non-union teachers than traditional public schools, range widely in quality from state to state.
While charter schools, on average, produced better results in states such as Louisiana, Massachusetts, Michigan, New Jersey, New York, Rhode Island and Tennessee, as well as Washington, DC, in some states, such as Arizona, Nevada, Ohio, Pennsylvania and Texas, the results were worse - in some cases, significantly worse.
The New York Times