The "Bread and Peace" model takes into account only two factors - real personal income growth and the number of American casualties in foreign wars. The same model predicted the losses of Jimmy Carter and George H.W. Bush.
Business Insider runs the numbers for 2012 and finds Obama should get just over 47% of the popular vote in November.
The model says that for each percentage point growth in Real Personal Income per capita - weighted so that recent changes have a stronger impact that earlier events - the popular vote percentage garnered by an incumbent increases 3.6%.
If Real Personal Income per capita grows 2% over a term, the president's popular vote percent goes up 7.2%. If weighted RPI per capita goes down 2%, the incumbent president's share of the popular vote decreases by 7.2%.
The second variable — American casualties in wars started by the U.S. — quantifies the impact wars like Vietnam and Korea have on the electorate. With the latest information on U.S. troops killed in Afghanistan, the model isn't significantly impacted.
Over Obama's term, 1,439 servicemembers were killed in Afghanistan. By our calculation there were only 4.6 Americans killed for every million Americans. In the model, that means Obama lost 0.2 points on the popular vote, altogether negligible. That variable is most significant during the Truman and Johnson elections, due to the high death tolls of the Korean and Vietnam Wars.