A few things to watch this Tuesday

EDIT: See also, FiveThirtyEight’s article on the same topic.

Off-year elections will be happening across the US this Tuesday, November 5th. Here are some races I’ll be keeping an eye on:

• Probably the most important election is in Virginia, where control of the legislative branch (both the Senate and House of Delegates) is up for grabs. The state legislature draws the legislative and Congressional district boundaries, so this election cycle is particularly important. Currently Republicans control 51 of 100 House of Delegates seats and 21 of 40 Senate seats (the governor, Ralph Northam, is a Democrat). I haven’t looked into this a bunch, but it looks to me like Democrats are favored to gain a few seats in the House of Delegates due to some district borders having been redrawn. I’d also guess that they’ll gain a couple seats in the Senate, because more close districts are currently held by Republicans than by Democrats. I would guess that at a 60/10/30 chance of a Democratic/tied/Republican House of Delegates and a 50/25/25 chance of a Democratic/tied/Republican Senate, but I don’t know much. (If an expert gives you a different impression, trust them, not me.) EDIT: These numbers are indeed bad — they underestimate Democrats’ chances. See below for further comment and here for the Washington Post’s ratings of individual seats (which imply that Democrats are essentially guaranteed to take the Senate and are very likely to take the House as well).
• The Mississippi gubernatorial election will likely be close, and it is pretty important because a medicaid expansion is much more likely to happen under a Democratic governor. There has been one high-quality poll of the race, showing Republican Tate Reeves up 3% over Democrat Jim Hood; this is also roughly the average of all the polls (most of which are partisan or low-quality). I’d say Reeves (R) has a 75% chance of winning the popular vote. But under Mississippi law, to be elected governor a candidate must win both the popular vote and the vote in a majority of Mississippi’s state House districts — otherwise the race goes to the (Republican-controlled) Mississippi House. This law is being challenged in court, however. I’d guess there’s an 85% chance that Reeves prevails, considering all this, but this might be pretty wrong.
• The Kentucky gubernatorial election will also likely be close. Democrat Andy Beshear is challenging Republican incumbent Matt Bevin, profiled by FiveThirtyEight as perhaps the most Trump-ish high-profile American politician besides Trump himself. Here too, medicaid expansion may rest on the outcome of the election. Beshear is up in an average of polls, but there have been only two recent polls and of these, the only high-quality poll showed a tie. I’d give Beshear (D) a 75% chance of winning, though I expect to have a more informed number closer to the election.
• New York City Question 1, if passed, would instantiate instant runoff voting in primary and special elections for local offices. By itself this isn’t super important, but I see this as the start of a movement toward a saner voting system (though for sure not my preferred one — that would be approval voting).
• This isn’t particularly important, but I want to see what percent of the vote Democrat James Mueller will get in the South Bend, Indiana mayoral election. Pete Buttigieg got 74% of the vote in 2011 and 80% in 2015. If Mueller gets something similar, I will view that as a small update against Buttigieg’s electability; if Mueller does substantially worse, that’ll mean that Buttigieg did better than one would naïvely have expected.

Also, coming up on Saturday, November 16th:

• The Louisiana gubernatorial election will be close as well. Democratic incumbent John Bel Edwards is running against Republican Ed Rispone. No high-quality polls have been conducted since the Republican primary on October 12th, but Edwards is up 6 points in the average of the (low-quality) polls. I’d give Edwards (D) a 75% chance of victory as well.

If any elections should have made this list but didn’t, let me know!

Update (11/4): When I wrote the probabilities above, I hadn’t looked at prediction markets. Here are my probabilities of Democrats winning each race, as compared with those of prediction markets:

I defer entirely to PredictIt on the first two of these, because I was guessing based on very little information, and mostly on the Mississippi Governor race where there’s a factor (see above) that I don’t have a good handle on. As for the last two, I don’t defer — I certainly update, perhaps 60% of the way toward PredictIt’s numbers, but I feel like PredictIt’s numbers aren’t totally reasonable. I’ve invested $50 into the Kentucky race: if the Republican wins, I’ll lose my $50; if the Democrat wins, I’ll gain $140.¹ It will be interesting to see how the Governor races go down. If the Republican wins all three races, that’ll make me (1) believe PredictIt more in general and (2) make me weight the fundamentals of the race (i.e. how liberal or conservative the state is) more relative to the polls than what I currently think is right.

^{1. My winnings would be lower than you’d have guessed based on the 1:9 odds I implied in the table primarily because of a 10% exchange fee.↩}