When the Eagles face the Cowboys on Sunday and the Patriots face the Jets on Monday night, two fierce N.F.L. rivalries will be renewed. But where do they rank among all the bitter rivalries in North American sports?

Any list of “greatest sports rivalries” is bound to be disputed. Make such a list, and be prepared for an onslaught of comments like “How could you leave out Maple Leafs-Canadiens?” and “What about Toledo-Bowling Green?”

So two business professors set out to try to find the biggest rivalries on an objective, statistical basis.

“People don’t agree,” said B. David Tyler, an associate professor at Western Carolina. “Some people say you can only have one rival. We decided to get some clarity on the idea.”