A mistake involving Haverford College casts new doubts about the popular, but often criticized, rankings of colleges and universities by media.

Forbes' annual list is out, and Haverford plummeted from No. 7 to No. 27 - for no obvious reason.

Eyebrows might also be raised over the volatility of two other stable Philadelphia-area schools - the University of Pennsylvania, now No. 17, way up from 52 a year ago, and Swarthmore, now No. 10, up from 16.

Princeton is back on top after finishing No. 2 to Williams last year.

Other schools in the region making the Top 100: Lafayette 49, Bryn Mawr 52, Villanova 83, and Franklin and Marshall 94.

In Haverford's case, Forbes relied on a federal database for thousands of schools that contained an error about the Main Line college's graduation rate, executive editor Michael Noer has confirmed.

Haverford correctly reported the rate as 88 percent, but it wound up listed as 55 percent, a dramatic difference.

The college's rank would "significantly improve" with the right numbers, Noer said.

But no revision is planned, since the magazine report is already in print, and the online list has already been published.

The mistake, however, will be prominently noted on Forbes.com's online page about the school, Noer said.

Haverford College spokesman Chris Mills explained that the error was based on single figure: A zero was wrongly entered instead of 108 for the graduation rate of white women who enrolled in 2004.

Graduation rates are indeed a significant piece of Forbes' ranking formula, counting 11.25 percent, behind post-grad success (32.5 percent), student satisfaction (27.5) and low debt burden (17.5), and tied with competitive awards.

The criteria are tweaked every year, and greater weight for post-graduate success this year may have helped propel Penn higher, Noer said.

Forbes' reliance on graduation rates had already been criticized for devaluing a school like Drexel University, where many students often attend for more than four years, to take full advantage of co-op and internship programs. Forbes ranked Drexel No. 525 - a far cry from the No. 88 accorded by U.S. News and World Report.

Beyond the mistake, Haverford declined to comment about such rankings, but they apparently haven't hurt the Main Line school in recent years.

"We continue to attract more applicants and they have ever stronger academic qualifications and they reflect ever greater diversity across demographic backgrounds," Mills said.

Other schools in the region ranked by Forbes: Dickinson 106, Lehigh 108, Muhlenberg 112, Gettysburg 119, Juniata 174, College of New Jersey 175, St. Joe's 180, Rutgers-New Brunswick 198, Ursinus 225, University of Delaware 240, Immaculata 245, La Salle 443, Temple 480, Rowan 561, Rider 568.

For more on Forbes higher-ed rankings, go to www.forbes.com.

Contact staff writer Peter Mucha at 215-854-4342 or pmucha@phillynews.com.