Some of this analysis is preliminary and subject to change if any states flip from what they look like now due to recounts or court cases. This assumes Biden will win the EC 306 - 232
538 correctly predicted 53 of the 56 electoral vote awarding entities (~95%). He only missed Florida, Maine CD-02, and North Carolina. He had Biden’s probability of winning each of those at less than 51%.
All of that is pretty good. What’s making him look bad is that all his misses were in the same direction so his modal EC outcome 351 - 187 looks pretty far off. But the actual outcome was right in the fat part of his projected distribution of all outcomes.
All that said, PredictIt ate 538’s lunch.
PredictIt was right in 54 of 56 EC awarding races. It only missed Georgia and North Carolina, missing one in each direction. The modal EC outcome per PredictIt was 305 - 233.
Here’s a slope chart of PredictIt probabilities (debiased for favorite/longshot bias) compared to 538 on election for races where either gave any party a 10% or greater chance to win. There were 18 such races and surprises outside these 18.
538 was more Biden leaning than PredictIt pretty much across the board.
Here’s that same info in table form with a column for results.
| Race | EV | PredictIt | 538 | Result |
|---|---|---|---|---|
| SC | 9 | 0.004 | 0.100 | 0 |
| AK | 3 | 0.015 | 0.149 | 0 |
| MT | 3 | 0.027 | 0.180 | 0 |
| IA | 6 | 0.140 | 0.399 | 0 |
| OH | 18 | 0.162 | 0.453 | 0 |
| TX | 38 | 0.238 | 0.382 | 0 |
| GA | 16 | 0.383 | 0.582 | 1 |
| FL | 29 | 0.417 | 0.691 | 0 |
| ME-02 | 1 | 0.520 | 0.573 | 0 |
| NC | 15 | 0.561 | 0.639 | 0 |
| AZ | 11 | 0.645 | 0.680 | 1 |
| PA | 20 | 0.749 | 0.843 | 1 |
| NE-02 | 1 | 0.837 | 0.717 | 1 |
| MI | 16 | 0.849 | 0.947 | 1 |
| NV | 6 | 0.876 | 0.878 | 1 |
| WI | 10 | 0.887 | 0.944 | 1 |
| MN | 10 | 0.897 | 0.958 | 1 |
| NH | 5 | 0.910 | 0.891 | 1 |
If you calculate Mean Squared Error across these 18 races, you get:
PredictIt → 0.0849
538 → 0.1225
Lower is better.
If you plot MSE error of both over time across al races you see that while both improved as the election drew closer, 538 was always worse. In fact, 538 in November was worse than PredictIt at any point going back to mid-April.
