WASHINGTON (AP) -- New research shows that low-income students who attend urban public high schools generally do just as well as those with similar backgrounds who attend private schools.

A study done by the nonpartisan Center on Education Policy looked at 12th-grade achievement tests in core academic subjects.

The finding is in line with some other recent studies, but it conflicts with a larger body of research over the years that shows private-school students generally do better than those in public schools.

The new research not only included income levels but also looked at other family characteristics, such as whether a parent takes part in school life. The report says when the other factors are included, the private-school advantage goes away.

The researchers tracked 1,000 low-income students over a period of years, along with parents and teachers, as part of a federal research effort.