A report on the nation's major research universities has given top national ratings to the University of Pittsburgh, Penn State University, Carnegie Mellon University and University of Pennsylvania for 2006.

The report is from the Center for Measuring University Performance at Arizona State University.

It studied schools with at least $20 million in federal research expenditures in fiscal year 2004 and looked whether they rank in the Top 25 on any one of various measures, such as research expenditures and doctorates awarded.

In the category of top public research universities, the University of Pittsburgh's main campus was one of seven campuses scoring highest, hitting the top 25 on nine standards. Penn State University's main campus was in the top 25 on seven standards.

In the category of top private research universities, the University of Pennsylvania was one of 11 to be in the top 25 on nine measures, the highest number. Carnegie Mellon was in the top 25 on five standards.

When public and private research universities are combined, Pitt tied for 23rd with three others, each of whom had four measures in the top 25. Penn State tied for 27th with six others who had three measures in the top 25.

Carnegie Mellon landed in the Top 50. University of Pennsylvania remained in the top five.