The October 2008 issue of PS published a symposium of presidential and congressional forecasts made in the summer leading up to the election. This article is an assessment of the accuracy of their models.

The Primary Model predicted that Barack Obama would win a narrow victory with 50.1% of the major-party vote. Obama surpassed that forecast by just a little more than one standard error (2.5). How come the model came as close as it did with a forecast issued as early as January? What prevented it from coming even closer? And what might be done to improve the model?