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] 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 may have come in on the money.
This is now the second time that a pure Meta-Analysis of state polls has predicted the winner and the EV breakdown within the confidence interval (2004 story here). Additional assumptions beyond state polls appear to have been unnecessary, at least this year.
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 undetermined races right, assuming that the current leads stand in the three closest states, Missouri, North Carolina, and Indiana. This gives 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 of the snapshot, Obama 353 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).
So although the bias is not significantly different from zero, it is also consistent with my assessment that the Bradley effect would be 0% and the cell-phone effect would be Obama +1%, for a net effect of Obama +1%. So let’s put the Bradley effect to bed.
I’ll have more assessments, including the Presidential popular vote, the Senate, the House, and turnout later this morning. In the meantime – I’m pleased.