We’ve been experimenting with presenting the probability as a decimal, on the grounds that the false precision of showing the ones-place is misleading. For example, “0.4″ means 40%. However, I’m not seeing a lot of love in comments about this change – a bit of a mixed reaction.
Note that the uncertainty (1 sigma) on the probability is at least 0.15, or 15% (and it’s asymmetric; more uncertainty in the D direction). For this reason, aggregators should not be showing a ones-place in the percentage; you don’t see “39%” in weather forecasts, and those are about as accurate as what we’re doing. We could also show it as ”40 +/- 15%”.
If you want to see the precise forecast of many aggregators, they’re all available at The Upshot (NYT). They just added PEC – many thanks to Josh Katz and the team there. The calculations all point in the same direction, a very gentle lean toward Republican control. However, everyone’s using the same polls, so a polling error would make us all wrong. Ponder that!
I’ll say it again – 60% is not that certain. If you flipped a coin weighted like that in favor of heads, 2 out of 5 times it would come up tails. The show’s not over.
Update: PEC’s November win probabilities are here, as well as piped over to the NYT.