October 29, 2008
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.
Posted by Robin Varghese at 04:00 PM | Permalink