New data on recidivism shows a mixed picture nationally for criminals who end up back in prison after being released.  The Pew Center on the States released its report "State of Recidivism: the Revolving Door of America's Prisons" Wednesday morning.

When it comes to recidivism rates, it's difficult to compare states, according to Adam Gelb, director of the Public Safety Performance Project for Pew. It’s more useful to look at how states perform over time, he said.

"We're looking to elevate the public discussion here about what these rates are and what they mean, and also, critically, to draw attention, primarily (from) policy makers, the public as well, into successful strategies--what's working well and what's not," said Gelb.

The study looks at state by state recidivism rates for two time periods: 1999 to 2002 and 2004 to 2007.  During that time, New Jersey's rate declined by more than 11 percent while Pennsylvania's rate jumped by more than 8 percent.

Pew researchers said the most effective strategies include incentives that reward good behavior, such as Pennsylvania's RRRI program.  That program, which lets non-violent offenders reduce their sentences by completing certain programs, started in 2008 after the reporting period for this study.

A Pennsylvania Department of Corrections representative said the recidivism rate in 2007 was about 15 percent less than the numbers from the Pew report.