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.

Prior to the 2008 presidential election we provided forecasts of the final vote relying on a model containing only two variables: (1) the cumulated weighted growth in leading economic indicators (LEI) through the thirteenth quarter of the sitting president's term; and (2) the incumbent party candidate's share in the most recent trial-heat polls. The novelty is the reliance on the advanced reading of the economy from the quarter ending in March of the election year. (The exact equation and the exact forecast change as the poll readings get closer to the election.) Our final forecast (Erikson and Wlezien 2008) based on trial-heat polls in August was that Barack Obama would win 52.2% of the two-party popular vote. This turned out to be quite close to the Election Day outcome of 53.5% (as of December 2), a little more than one percentage point above what we predicted.