The October 2008 issue of PS published a symposiumof presidential and congressional forecasts made in the summerleading up to the election. This article is an assessment of theaccuracy of their models.

Prior to the 2008 presidential election we provided forecasts of thefinal vote relying on a model containing only two variables: (1) thecumulated 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 recenttrial-heat polls. The novelty is the reliance on the advancedreading of the economy from the quarter ending in March of theelection year. (The exact equation and the exact forecast change asthe 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 win52.2% of the two-party popular vote. This turned out to be quiteclose to the Election Day outcome of 53.5% (as of December 2), alittle more than one percentage point above what we predicted.