Reasonable bounds on presidential election outcomes

How can we know how wide the tails should be?

FiveThirtyEight launched their 2020 election model this week. It’s much less certain than the alternative available, such as that from The Economist or a lesser-known forecaster named Jack Kersting. 538 gives Biden a 72% chance of winning, and the others are in the mid-to-high 80s.

Nate Silver has offered up a ton of justification for why his model is th…