Remember back on Monday and Tuesday when this blog and several others were cautioning everyone to ignore leaked early exit polls?
I figured I should go back and check to see whether that advise turned out to be sound or not. Quick answer: yes. Ignoring the exit polls and using the pre-election polls gave a much better indication of what was happening.
One thing that's changed is that we no longer get early exits leaked as early as we used to. In the old days, insiders would hear about exit polls in midday, reflecting the earliest wave of polling. Now, the networks really don't allow anything to leak until much later; of course, when it does leak, everyone with a computer hears about it.
So when they did leak in late afternoon or early evening (and Taegan Goddard's wonderful Political Wire reported them), how useful were they?
The leak, as Goddard reported, included 11 states.
First cut: compared to nothing at all, the leaked exit polls (LEPs) did okay. They reported leads in 9 states, and only had one wrong: the LEPs had Romney up one in Florida, but Obama won it by 0.6. The LEPs were within three points in all but two states. That seems at least somewhat useful. However, there was also a solid pro-Romney bias in the LEPs; In nine of the eleven states, the LEPs had numbers better for Romney than the actual results.
Second cut: Add all that up, and the LEPs gave the mistaken impression of a narrow and not certain Obama win. With Florida leaning Romney and Virginia and Colorado tied, the LEPs had the election Obama 281, Romney 235, undecided 22. With Ohio one of the two states where the LEPs favored Obama (showing a four point lead, while it wound up only two), there was no obvious way for Romney to get the rest of the way, but a whole bunch of targets: he was losing in the LEPs by three in Minnesota, Iowa, and New Hampshire, and by four in Ohio, Pennsylvania, Wisconsin, and Minnesota. For what it's worth, there were no LEPs, at least in this set, for Michigan, New Mexico, or Oregon. So what you're left with if you were hoping for Romney was that the supposedly tied states would go his way, and that somehow he would find another 13 EVs. Unlikely, but perhaps slightly more likely than what the polling aggregators and predictors had been saying.
Third cut: but that's when we get to why these LEPs were actually totally useless. Going back to HuffPollster's final polling averages, the LEPs beat pre-election polls in only New Hampshire and Nevada, and New Hampshire only by a bit (Obama's lead was 3 in LEP, 2.5 in HuffPollster; the vote was a 6 point win). In three other states, LEP and HuffPollster were tied. So in six of eleven states, using the pre-election polls was better than using the leaked exit polls. Or, if we want to look at the simple average miss, the LEPs averaged miss was 2.8, while HuffPollster in these states averaged 2.2.
So, yeah, remember it for next time: ignore leaked early exit polls.