FiveThirtyEight’s Election Updates are back! This will be a regular feature in which we track the race for the House (and, eventually, Senate and governors’ offices) using our forecasts to highlight particularly interesting trends and races.
According to the latest run of the “Classic” version of our model, Democrats have a 3 in 4 chance of taking over the House; their average gain is 34 seats. This hasn’t changed too much since we launched the forecast last Thursday, when Democrats’ average gain was 35 seats. However, there have been some changes under the surface as we’ve made improvements to the model. You can find an overview of those here, and we’ll be updating our “how the forecast works” page soon with more detail.
But since this is our first Election Update, today I want to focus on the bigger picture. Our model joins the political discourse as only one of many predictors of the fall’s elections, and three of the most respected election handicappers are our friends over at the Cook Political Report, Inside Elections and Sabato’s Crystal Ball. Historically, their race ratings have a strong record of accuracy — so much so that we have a whole iteration of our forecast, the “Deluxe” version, that exists solely to incorporate their ratings. So, while we remain devoted to hard data above all, it’s always good to see how our bloodless, but systematic, approach matches up with more subjective, but expert, opinions.
And, generally, they do. As of Tuesday, Cook, Inside Elections, Crystal Ball and FiveThirtyEight’s Classic forecast all had the same race rating for 322 out of the 435 House races.1 FiveThirtyEight agreed with or was only one category removed from Cook in 424 races, Crystal Ball in 423 races and Inside Elections in 410 races. Our mileage may vary in whether to call a GOP-favored race “lean Republican” or “likely Republican,” but, generally, our different techniques are leading mostly to the same results.
But there are also some differences. For example, FiveThirtyEight’s forecast is a tad more bullish on Democrats’ chances overall than the three major handicappers. If you assign probabilities to their race ratings,2 Cook’s and Sabato’s ratings both imply a Democratic gain of 29 seats, while Inside Elections’s compute out to a Democratic gain of 23. (Our forecast, remember, currently projects an average Democratic gain of 34 seats.)3
The Democratic tail is also longer in our Classic forecast — that is, the model gives a greater chance than the experts do that a blue wave turns into a tsunami and Democrats pick up a ton of seats, like 60 or 70. That’s because the model rates fewer seats as truly safe for Republicans — or “solid” in FiveThirtyEight parlance — than the experts do.
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By a small margin, our forecast also places more seats in the “solid Democratic” category and all the competitive categories combined (between “likely Republican” and “likely Democratic”).
Who will be right? We honestly don’t know! We’re still 11 weeks out from the election, and things are still subject to a lot of change. The long tails in our forecast reflect that, but it’s worth noting that there’s no real way for the qualitative ratings to communicate uncertainty. The bottom line is that, in the big picture, and in terms of average seat gain, all the major forecasters agree: Democrats are mild favorites to take back the House.
Check out all the polls we’ve been collecting ahead of the 2018 midterms.