Post-election evaluation: the Meta-Analysis worked

[DemocratSinceBirth]

Good morning! First, congratulations to President-elect Barack Obama. It’s a historic day. His campaign inspired millions. But also condolences for his grandmother’s passing - what a loss, and at what a time.

Let’s take a quick look at the performance of the Meta-Analysis and my other predictions. Preliminarily, things look quite good.

The EV total. The final snapshot was Obama 352 EV, McCain 186 EV, with a 68% confidence band of <337,367> Obama EV. My personal prediction was Obama 364 EV, McCain 174 EV. With a tentative result of Obama 364 EV, McCain 174 EV, it looks like we came in right on the money.

Individual states and the mode. The median of the last-3-polls-and-last-week-of-polling got the outcome right in 47 out of 47 cases where the margin was greater than 1%. Of the remaining four, three were ties and one was incorrect (North Carolina). That makes 47 out of 48. The tie-breaking procedure I adopted yesterday morning got three out of four close races right, leading to an overall record of 50 out of 51 states correct. The exception was Indiana, which Obama is leading by 0.9%. That made the mode prediction, Obama 352 EV, off by 11 EV.

Overall polling bias. I gave you tools for finding a difference between the results and the polls. Based on the final EV total above, the bias seems to be about 1% in favor of Obama, (68% CI +/-1%). That matches well with the average difference in individual state true margins, Obama +0.7 +/- 0.8% (mean +/- SE, n=51).

http://election.princeton.edu/2008/11/05/post-election-results/