Forecasting the Election & The Open Question of Racism

For the technically minded, in the October 2008 issue of PS: Political Science and Politics, there’s an interesting symposium on forecasting the election, and at you can find an associated video of a panel with many of the scholars.  From Michael S. Lewis-Beck and Charles Tien ‘s piece:

Our Jobs Model forecasts that the Republicans, now incumbent in the White House, will experience a shattering defeat, indeed the greatest incumbent popular vote loss on record from 1948, garnering just 43.4% of the two-par ty popular vote. How accurate is this forecast? Consider simple statistical error. The standard error of estimate is 1.4; but adding even three times that amount to the point forecast would still predict a clear Republican loss ~at 47.7%!. Put another way, if Obama receives less than 50% of the popular vote, the Jobs Model would have registered an error of over 6.6 points. That would be the largest out-of-sample error in the data-set. It implies that there is less than a 1 in 14 chance that the model is wrong in forecasting an Obama victory.

Nevertheless, the Jobs Model is not a “shoo-in” for Obama, once ballot box racism is taken into account. By various estimates, Obama will lose a chunk of votes because he is Black, rather than White. This seems unavoidable. In the foregoing, we evaluated four possible correction values: 0.77, 0.87, 0.90, and 0.93. Which is closer to the truth? In order to avoid appearing arbitrary, we simply take the median of these four values ~0.885! as the proportion of voters who will not take race itself into account. By that reckoning, Obama would win in a close contest ~i.e., a 0.885 correction to the Jobs Model predicts an Obama two-party popular vote forecast of 50.1%!. 3 But if the correction number is lower, by even a small amount, he could well lose. In any event, we expect the competition to be much closer than what is implied by our original, uncorrected Jobs Model.