Republicans Need A Systematic Polling Error To Win The House

[RandySF]

How hard is that? Because of the possibility of a systematic polling error, it isn’t really that hard at all. If there’s a typical polling error of 2 to 3 percentage points and it works in Republicans’ favor, the House would be a toss-up. We might not even know the winner for several days as everyone waits for additional mail ballots to be returned from California. Thus, the Lite forecast gives Republicans a 2 in 9, or 22 percent, chance of keeping the House based on the possibility of a systematic polling error. Their chances are 18 percent in Deluxe and 15 percent in our Classic version, meanwhile.

That isn’t a great position, but those are real, tangible chances.

Without the possibility of a systematic polling error, however, the GOP’s position is nearly hopeless. If all races were independent from one another and GOP chances in the most competitive races were approximately 50-50, the Republicans would have to do the equivalent of have a coin come up heads at least 24 times in 34 attempts. That’s really hard. The probability of ending up with at least 24 heads in 34 tries is only about 1 in 80.

We can also come up with a more sophisticated version of this coin-flip calculation. Instead of putting the races into different buckets and treating them as 50-50, we can just use the probabilities listed by the Deluxe model in each of the 435 districts — that Republicans have an 83 percent chance of winning New York 24, for example. We can run a Monte Carlo simulation to see how often Republicans wind up with at least 218 seats. The answer is that, assuming that races are independent — again, a bad assumption, but what you get in a world in which there isn’t systematic polling error — Republican chances of holding the House are only about 1 in 1,000.

What if we use the Lite version of our calculations instead? Lite is essentially a “polls-only” forecast; it uses district-level polls in districts where it has enough of them and national (generic congressional ballot) polls and polls of similar districts to make inferences in districts where it doesn’t. If you run a Monte Carlo simulation with our Lite forecast — assuming that each district is independent — Republican chances aren’t much better, about 1 in 700.

But why is it so hard for Republicans to win the House without a systematic polling miss? The short answer is because they’re defending too much territory: The House playing field is exceptionally broad this year, because of Republican retirements, an influx of Democratic cash and other factors. The decisive race won’t necessarily be in a toss-up district; it could very easily be in a “likely Republican” district where a GOP incumbent is caught sleeping at the wheel (perhaps a district where there hasn’t been much polling).

To help illustrate the breadth of the playing field, I’ve sorted every House district based on the projected margin of victory or defeat for the Democratic candidate, according to the Deluxe model, and ordered them from No. 1 (the easiest seat for Democrats to win) to No. 435. Except, I’m only going to show you the districts in the middle of the spectrum; everything from district No. 190 (if Democrats won only 190 districts, they’d lose a net of five House seats) to No. 295 (a net gain of 100 seats).2


https://fivethirtyeight.com/features/republicans-need-a-systematic-polling-error-to-win-the-house/

[YessirAtsaFact]

1. I think there is a systemic polling error in our favor

And we take both House and Senate

[Kurt V.]

2. Ignore polls.

vote.

[YessirAtsaFact]

3. I can look at polls and vote too

And I think that there is a deluge of new voters that are underrepresented.

I look forward to Tuesday, with my first time voter wife, second time voter step-son and me getting to the polls early.

[Kurt V.]

4. true. and way to go, getting the family out to vote!