Originally published September 25, 2012 at 10:25 a.m., updated September 25, 2012 at 2:31 p.m.
Lynn O'Shaughnessy, author of "The College Solution"
When U.S. News ranked UC San Diego the 38th best national university and eighth best public university and ranked San Diego State 165th best university overall, many take it for granted that there is an objective, perhaps even scientific, methodology to such rankings.
The U.S. News rankings, however, differ markedly from some others, notably Washington Monthly, which ranks UC San Diego number one, and Forbes, which ranks the university 117th.
Lynn O'Shaughnessy, author of "The College Solution," told KPBS the differences lie in the criteria and the methods.
The biggest factor in the U.S. News rankings is an institution's reputation. Each school surveys all the others in their category. In the national category, there are 268 universities. Consequently, an institution is asked to judge hundreds of schools they know nothing about, so these rankings often measure how elite, wealthy and prestigious an institution is.
"It's not a scientific methodology," O'Shaughnessy said. "The major factor is what all the schools think of each other."
"So of course it's absurd," she added. "What does somebody at San Diego State know about what's going on at University of Connecticut or University of Missouri? It's a flawed way of evaluating schools."
She said when people making rankings are unsure of how to rank other schools, they look at U.S. News to see how those schools have been ranked in the past.
Forbes attempts to categorize schools based on educational experience, return-on-investment and amount of debt after graduation.
O'Shaughnessy said Forbes rankers look at websites like ratemyprofessor.com to see what students say about their professors. She said they also look at whether students get jobs when they leave the school and payscale.com figures.
"That's not ideal either because it's self reported, but it's better than not looking at student outcomes at all," she said.
Rankings often are of little help to students and their parents, she said, because relying on them may mean that students never consider dozens of good schools not high on a list. And schools high up in the rankings often have extremely low acceptance rates.
Claire Trageser contributed to this report.