Last month (“Using predictions in the service of ideals and profit,” Sept. 23) I asked what makes a good prediction. I made an analogy to hur...
After the storm
We shall not cease from exploration
And the end of all our exploring
Will be to arrive where we started
And know the place for the first time. -T.S. Eliot
Good morning! The day after the election is always a bit of a relief for me. We’re still waiting on a few races, but here’s a preliminary look back at how our polls-only approach did. All in all, extremely well. As Randall Munroe sent me last night: “BREAKING: Numbers continue to be best tool for determining which of two things is larger.”
In the races called thus far, pre-election polling medians were correct in 50 out of 50.
There is one race remaining, Florida, where Obama leads Romney by 49.91% to 49.36%, with 100% of votes counted. It hasn’t been declared yet, partly because the threshold margin for a recount is 0.5% – they are probably still working that out. Pre-election polls were a near-perfect tie. I suspect I am about to lose that coin toss. Update, 11/15: final Florida result, Obama 50.0% Romney 49.1%.
The two-candidate popular vote share is Obama 51.1% to Romney 48.9%. This exactly matches my prediction, which was derived from state polls with a little Bayesian help from national polls. Update, 11/15: popular vote Obama 51.4% Romney 48.6%.
Bottom line: I will not have to eat a bug.
Senate: Of the closest races, election returns match polling medians in 10 out of 10. Of particular note is the North Dakota race, where Heitkamp (D) leads Berg (R), 50.5-49.5%. That’s one where I had Heitkamp based on polls, and Nate Silver had Berg based on polls plus other factors. We are also waiting on the Montana race, where Tester (D) leads Rehberg, 49-45%. The upper chamber appears headed right for the median that we predicted, 55 D/I to 45 R.
House: This one will take some time to sort out. From the Republicans’ current majority of 242 seats, I predicted losses of 2-22 seats. It looks like the losses will be toward the low end of that range.
I am very interested in whether Democrats win the national House popular vote, which would mean a mismatch between the vote and the seat count. This is due in part to redistricting. It would be only the second time since World War II that it’s happened, and is antidemocratic with a small “d.”
I’ll give a more detailed look later, especially regarding our prediction challenge. For now, I think we can safely say that the following people had a good outcome: President Obama, Congressional Democrats, and quantitative poll analysts.
Finally, a trip down memory lane: the Princeton Election Consortium long-term predictor, as of August 3rd:
Back in a bit with more wrap-up…