Reuters reports that Ray Fair, a Yale University economist who has been predicting elections with remarkable accuracy over the last several decades, is calling for an Obama victory on November 4. How so? The economy is in the tank. And his model predicts that a strong economy benefits the party of the incumbent and a weak one is great for the challenger.

Fair's model predicts Obama will win 52.2% of the vote to McCain's 47.8%, according to Reuters. And that's based on a relatively optimistic set of economic assumptions. In April, Fair ran the numbers assuming U.S. economic growth of 1.5% and a 3% rate of inflation. But in the fourth quarter of 2007, GDP growth was revised to a negative 0.2%. And despite 0.9% growth in the first quarter and 1.9% growth in the second quarter, it would not surprise me to see those numbers revised into negative territory. Meanwhile, inflation, most recently roaring ahead at 5%, is way above Fair's prediction.

Another similar model developed by Macroeconomic Advisers -- which Reuters reports has correctly predicted the winning party 12 out of 14 times -- uses more recent data to suggest that in light of the dismal economic conditions McCain will get 45% of the vote in November. Who knows whether these models will work for this election? In the meantime, they suggest that the worse the economy gets, the better it is for Obama.

Peter Cohan is President of Peter S. Cohan & Associates. He also teaches management at Babson College and edits The Cohan Letter.