Closeness counts in horse shoes, dancing, and forecasting

On September 10, 2012, immediately following the close of the Democratic Party's national nominating convention and 57 days before Election Day on November 6, my Convention Bump and Economy Model predicted that Barack Obama was likely to receive 51.3% of the national two-party popular vote. The Convention Bump and Economy Model consists of Gallup's preconvention preference poll, the net convention bump in the polls, and an adjusted second quarter GDP growth rate. The forecast pegged the certainty of an Obama plurality at 67%. No sure thing, but more likely than not. The traditional Trial-Heat and Economy Model predicted Obama's vote at 52.0%. The Convention Bump and Economy Model's prediction was the preferred forecast in 2012 because of the lateness of the parties' nominating conventions. Democrats did not even begin their convention until after Labor Day.