The city's charter schools are getting some high marks from researchers on the west coast.

A new report from Stanford University says about 63 percent of the charter schools studied outperformed traditional public schools, while about 14 percent performed worse.

The researchers also looked at the amount students learned during the year.

In reading, students in New York's charter schools advanced by an additional month of learning and an additional five months in math.

The study also showed that students achieve more in math in their first year at charter schools.

A national study from 2009 had different results, saying first-year charter-school students struggled in both reading and math, but improved in following years.

There are now more than 100 charter schools across the city.