Back at the OG version of FiveThirtyEight.com in 2008, we ran a daily feature called “Today’s Polls”. It was pretty simple: basically a table of every poll that had entered our database in the past 24 hours, with brief commentary on the most noteworthy polls and how they’d affected our forecast.
“Today’s Polls” was quite popular, but I don’t think that quite works for us now. We think that updating FLIPR daily, with 2-ish Model Talks or other election-related articles a week, strikes a better balance in serving our subscribers. To some extent, there was an inherent tension between commenting on individual polls and the usually fairly measured reaction that our model had to them.
Still, keeping tabs on the “information flow” — the new data entering the model — can be helpful. This is tricky in election forecasting, because “new information” isn’t quite the same thing as “news”. Some information is important to FLIPR from a technical standpoint but doesn’t change the fundamentals of the race as such. The slight decline in Democrats’ win probability in the Senate that I discussed on the podcast this week was kind of in the technical category. It mostly reflected updates to the model’s likely voter adjustment and changes in expert ratings, rather than any sudden shift in the polling.
Over the past few days, however, Democrats gained that ground back — and then some, depending on which version of our forecast you’re looking at. The cause of the recent movement is straightforward: polls over the past week or two have mostly been good news for Democrats.
In our Deluxe forecast, they’re back up to a 56.5 percent chance of winning the Senate, basically where they were when we launched the model. We’d aggressively caution that 56.5 percent is still in the zone that our model classifies as a “toss-up” and is consistent with a really close race. But, hey, it never hurts to be on the 56/44 side of a slightly weighted coin flip.
But in our Lite forecast, which relies as much as possible on polling of individual races, the change has been more pronounced: