Nate Silver (and others) Dance with the Green Knight

Since almost no people have the relevant expertise to build political forecasting models (it takes tons of work and even then is easy to get wrong), political betting markets are basically just a competition over what types of people suffer more from the Dunning–Kruger effect.

— Nate Silver (@NateSilver538) October 29, 2020

Nate has been dismissive of the election markets this cycle. He’s noted his own model is much more confident in Biden. Fair enough. Let’s let them battle. However, this isn’t simple Full Kelly wagering. That’s easy mode. Nate’s claim is quite bold, so let’s give him a chance to prove it.

Credit Kai Carpenter, “Sir Gawain and the Green Knight”

Nate shall get a half-Kelly bet into the markets and the markets shall in turn get a half-Kelly wager into Nate’s numbers. Each side shall have identical vig on each wager. All of this was recorded on the final Saturday before the election. Let’s start with the main event:

Biden-President

133.44%

29.62%

0.00%

To explain how this works, let me break that down into the two individual bets:

Nate into the market	Biden-President	34.70%	16.84%	0.00%
The market into Nate	Trump-President	12.77%	98.74%	0.00%

The market was offering Biden -206, Trump +181. Nate was offering Biden -1070, Trump +773. Identical vigs, two half-Kelly wagers.

That’s a lot of confidence in the Biden. Let’s break it down state-by-state:

Biden-AK	2.56%	16.96%	0.00%
Biden-AZ	29.49%	16.96%	0.00%
Biden-FL	49.21%	42.10%	0.00%
Biden-GA	29.71%	29.50%	0.00%
Biden-IA	9.94%	14.03%	0.00%
Biden-ME	3.17%	0.39%	0.00%
Biden-MI	205.84%	23.45%	0.00%
Biden-MN	200.16%	20.03%	0.00%
Biden-MT	7.66%	65.51%	0.00%
Biden-NC	31.58%	20.90%	0.00%
Biden-NH	68.99%	12.32%	0.00%
Biden-NM	128.52%	10.28%	0.00%
Biden-NV	83.15%	15.63%	0.00%
Biden-OH	20.71%	34.64%	0.00%
Biden-PA	107.33%	31.84%	0.00%
Biden-TX	15.14%	33.84%	0.00%
Biden-WI	168.20%	22.70%	0.00%

Michigan and Minnesota are of special interest here as Nate has gone HAM (as have the markets, betting into Nate). Florida is worth noting as well given how strongly Nate has Biden favored. Wisconsin, Pennsylvania, and Georgia are all key states where Nate has shown significant confidence in Biden.

There will be a lot of eyes on Senate control as well:

Dem-Senate Control

54.15%

22.89%

0.00%

There are a number of competitive races to watch:

AK-Dem Senate	5.34%	20.59%	0.00%
AL-Dem Senate	6.03%	36.75%	0.00%
AZ-Dem Senate	4.84%	1.21%	0.00%
CO-GOP Senate	0.93%	5.79%	0.00%
GA-Dem Special	40.85%	35.97%	0.00%
IA-Dem Senate	3.86%	3.58%	0.00%
KS-Dem Senate	2.60%	9.54%	0.00%
ME-GOP Senate	8.76%	15.45%	0.00%
MI-Dem Senate	42.78%	13.43%	0.00%
MN-Dem Senate	82.02%	11.01%	0.00%
MS-Dem Senate	2.49%	17.67%	0.00%
MT-Dem Senate	1.73%	3.44%	0.00%
NC-Dem Senate	9.30%	5.50%	0.00%
TX-GOP Senate	0.44%	0.05%	0.00%

Michigan and Minnesota are fairly strong opinions, but I’m most fascinated by the GA Dem Special. Nate is predicting a Dem pickup there. The markets are skeptical.

As for the House I must confess there is significant less liquidity in these markets (save for House control), but for science I’ve recorded them:

Dem-House Control

141.97%

9.63%

0.00%

That seems like an easy pickup. As for the individual races:

Dem-CA 26	32.67%	10.92%	0.00%
Dem-CO 3	3.07%	4.85%	0.00%
Dem-IA 1	26.19%	4.91%	0.00%
Dem-IA 2	55.86%	11.67%	0.00%
Dem-IA 3	35.03%	8.81%	0.00%
Dem-IL 13	3.35%	5.88%	0.00%
Dem-MI 3	21.68%	36.12%	0.00%
Dem-MI 6	1.65%	4.27%	0.00%
Dem-NC 11	5.91%	19.44%	0.00%
Dem-NC 8	2.33%	4.50%	0.00%
Dem-NJ 3	72.32%	10.56%	0.00%
Dem-NY 2	5.46%	8.96%	0.00%
Dem-OH 1	7.07%	12.64%	0.00%
Dem-PA 10	12.96%	18.90%	0.00%
Dem-VA 2	23.22%	4.27%	0.00%
Dem-VA 5	29.26%	33.09%	0.00%
GOP-AZ 6	7.45%	6.09%	0.00%
GOP-CA 21	8.83%	13.88%	0.00%
GOP-CA 25	4.74%	7.33%	0.00%
GOP-CA 48	1.02%	2.62%	0.00%
GOP-GA 7	33.02%	44.37%	0.00%
GOP-KS 2	11.58%	1.62%	0.00%
GOP-MO 2	18.75%	12.46%	0.00%
GOP-NJ 2	1.90%	1.97%	0.00%
GOP-NM 2	3.35%	5.88%	0.00%
GOP-NY 11	9.95%	16.00%	0.00%
GOP-NY 24	7.84%	5.90%	0.00%
GOP-PA 18	48.30%	16.44%	0.00%
GOP-TX 21	9.61%	6.38%	0.00%
GOP-TX 22	40.88%	39.56%	0.00%
GOP-TX 24	21.87%	24.93%	0.00%
GOP-UT 4	10.36%	17.72%	0.00%
GOP-WI 3	1.38%	9.78%	0.00%

G. Elliot Morris of the Economist has been equally dismissive of markets, even while sparring with Nate over modeling choices. In fact, Morris has been much more confident in Biden than Nate for the bulk of this cycle:

Biden-President

306.25%

36.44%

0.00%

This shows up on the state level as well:

Trump-AK	39.76%	3.72%	0.00%
Trump-MT	101.88%	4.09%	0.00%
Biden-AZ	61.40%	28.25%	0.00%
Biden-FL	99.57%	61.18%	0.00%
Biden-GA	27.31%	27.69%	0.00%
Biden-IA	11.76%	16.27%	0.00%
Biden-ME	138.75%	9.51%	0.00%
Biden-MI	317.59%	25.59%	0.00%
Biden-MN	858.99%	24.26%	0.00%
Biden-NC	39.61%	24.69%	0.00%
Biden-NH	438.80%	22.12%	0.00%
Biden-NM	167.43%	11.85%	0.00%
Biden-NV	176.92%	21.20%	0.00%
Biden-OH	9.62%	18.34%	0.00%
Biden-PA	260.58%	41.33%	0.00%
Biden-TX	0.48%	1.36%	0.00%
Biden-WI	302.27%	25.95%	0.00%

Minnesota or bust, eh? Wisconsin, Pennsylvania, New Hampshire, and Michigan are all fairly huge as well. As with Nate, we see Florida as a fairly strong play.

There’s confidence in the Dems in the Senate as well.

Senate-Dem Control

90.59%

30.60%

0.00%

We see that show up in the individual races:

AK-Dem Senate	10.66%	36.86%	0.00%
AL-GOP Senate	63.37%	4.59%	0.00%
AZ-Dem Senate	50.29%	9.57%	0.00%
CO-GOP Senate	75.04%	6.83%	0.00%
GA-Dem Senate	31.66%	28.48%	0.00%
GA-Dem Special	35.45%	32.59%	0.00%
IA-Dem Senate	10.43%	9.10%	0.00%
ME-Dem Senate	7.40%	3.20%	0.00%
MI-Dem Senate	188.80%	28.55%	0.00%
MN-Dem Senate	139.53%	14.74%	0.00%
MT-Dem Senate	1.73%	3.44%	0.00%
NC-Dem Senate	35.44%	17.24%	0.00%
SC-Dem Senate	16.22%	40.07%	0.00%

Plenty of headliners here, but it’s Georgia that is holding my attention. Both races will be fascinating.

There’s a similar tale in the House:

House-Dem Control

146.47%

10.19%

0.00%

As for the individual races:

Dem-CA 21	11.53%	5.27%	0.00%
Dem-CA 39	8.71%	2.25%	0.00%
Dem-FL 26	198.22%	30.68%	0.00%
Dem-GA 7	20.57%	7.57%	0.00%
Dem-GA 7	124.86%	16.33%	0.00%
Dem-IA 2	111.28%	17.29%	0.00%
Dem-IL 13	18.91%	27.46%	0.00%
Dem-MI 3	13.01%	23.97%	0.00%
Dem-MI 6	20.11%	39.58%	0.00%
Dem-MT at Large	11.02%	24.92%	0.00%
Dem-NC 8	8.70%	15.21%	0.00%
Dem-NJ 2	3.12%	2.43%	0.00%
Dem-NJ 3	72.32%	10.56%	0.00%
Dem-NJ 7	70.57%	11.30%	0.00%
Dem-NV 4	190.12%	22.31%	0.00%
Dem-NY 2	14.11%	20.86%	0.00%
Dem-NY 22	84.59%	21.19%	0.00%
Dem-NY 24	16.97%	15.05%	0.00%
Dem-OK 5	5.18%	4.31%	0.00%
Dem-OR 4	139.53%	14.74%	0.00%
Dem-PA 10	33.16%	39.63%	0.00%
Dem-SC 1	10.33%	4.50%	0.00%
Dem-TX 21	1.00%	1.21%	0.00%
Dem-TX 24	21.22%	11.03%	0.00%
Dem-TX 7	68.06%	11.93%	0.00%
Dem-UT 4	24.78%	8.88%	0.00%
Dem-VA 2	68.95%	9.92%	0.00%
GOP-CA 25	23.33%	29.45%	0.00%
GOP-CO 3	21.48%	9.98%	0.00%
GOP-FL 15	30.67%	5.43%	0.00%
GOP-KS 2	40.22%	4.97%	0.00%
GOP-MO 2	56.06%	28.55%	0.00%
GOP-NE 2	5.71%	5.40%	0.00%
GOP-NY 11	6.59%	11.06%	0.00%
GOP-PA 1	29.40%	11.29%	0.00%
GOP-TX 22	6.23%	8.35%	0.00%

Finally, there’s the Epstein-Bitecofer model. You might remember them from the Biden 99.5% projection:

Re: Bitecofer-Epstein Model, 99.5% Chance of Biden Victory
To address some of the questions about our model, I'm going to keep this thread 🧵🧵🧵 going to talk about the final result we got: 99.5% chance of victory for Biden. One of the reasons that we have such a high prob.

— 🦇🎃👻 Sam Epstein 👻🎃🦇 (@sam_epstein) September 17, 2020

Yo, I like that you’re making use of standard error now! But can you tell me how much error these simulations are generating? 99.5% D seems far too high, but I don’t see enough information in the methodology to figure out why. We can email if you’d like. Cc @sam_epstein

— G. Elliott Morris (@gelliottmorris) September 16, 2020

That was… something. They’ve come a bit closer to reality and were at 93.4% at the time of my tracking. That’s leads to a Presidential wager that almost seems reasonable in comparison:

Biden-President

201.43%

33.52%

0.00%

Different model. Same confidence in Biden in Minnesota:

Biden-AK	24.85%	105.92%
Biden-AZ	98.43%	36.15%
Biden-FL	93.92%	59.65%
Biden-GA	24.98%	25.85%
Biden-ME	105.38%	7.98%
Biden-MI	66.48%	14.53%
Biden-MN	200.16%	20.03%
Biden-NC	80.72%	38.19%
Biden-NH	154.29%	17.86%
Biden-NM	167.43%	11.85%
Biden-NV	214.25%	22.28%
Biden-OH	2.65%	5.58%
Biden-PA	142.71%	35.47%
Biden-TX	40.92%	70.06%
Biden-WI	21.15%	6.30%

Pennsylvania is also worthy of note. As for the Senate:

Senate-Dem Control

65.65%

25.77%

0.00%

There’s more excitement in some of the individual races:

AK-Dem Senate	14.86%	47.89%	0.00%
AL-GOP Senate	27.12%	1.90%	0.00%
AZ-Dem Senate	21.52%	4.88%	0.00%
CO-Dem Senate	75.04%	6.83%	0.00%
GA-GOP Senate	4.25%	3.08%	0.00%
IA-Dem Senate	1.76%	1.67%	0.00%
ME-Dem Senate	94.67%	23.70%	0.00%
MI-Dem Senate	115.28%	24.09%	0.00%
MN-Dem Senate	68.95%	9.92%	0.00%
MT-GOP Senate	35.53%	12.63%	0.00%
NC-Dem Senate	74.28%	27.94%	0.00%
SC-Dem Senate	7.36%	20.79%	0.00%
TX-Dem Senate	5.34%	20.59%	0.00%

We’ll see how all of this goes. They have House ratings, but not quantifiable projections, so my job is done. Again, all of this was recorded on the final Saturday before the election.

Good luck to everyone involved and may all your votes count!

hmmmmmm are people anxious about “the polls” or anxious that the votes won’t matter?

— Patrick Sullivan (@BasicMountain) November 1, 2020