New Jersey charter schools are outperforming traditional public schools.

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A Stanford University study found charter students averaging an additional two months of learning a year in reading, three months annually in math compared to public schools. The study was performed by Stanford's Center for Research on Education Outcomes, and covered grades 3 through 8 for the years 2007 to 2011.

"These schools are excelling with a high proportion of minority students in poverty," read the report. "These schools' practices may be instructive for other public schools that also serve this student group."

Co-author Devora Davis says the differences were even larger for black and hispanic poor students enrolled in charters. They show a significantly better performance in both reading and math when compared to black and hispanic students who are in traditional public schools. Charters in Newark did particularly well compared with traditional schools there.

The study found that 30 percent of charters do better than their counterparts at teaching reading and 11 percent did worse. In math, 40 percent of charters do better and 13 percent do worse.

New Jersey Charter Schools Association Executive Director Carlos Perez says, "It's great to have the data, and it's great to have a report like this."

State Education Commissioner Chris Cerf says study results mirror the work they are doing to increase and enhance school accountability standards.