Tyler Cowen and Kevin Grier mention a curious fact:

Economists Andrew Healy, Neil Malhotra, and Cecilia Mo make this argument in afascinating article in the Proceedings of the National Academy of Science. They examined whether the outcomes of college football games on the eve of elections for presidents, senators, and governors affected the choices voters made. They found that a win by the local team, in the week before an election, raises the vote going to the incumbent by around 1.5 percentage points. When it comes to the 20 highest attendance teams—big athletic programs like the University of Michigan, Oklahoma, and Southern Cal—a victory on the eve of an election pushes the vote for the incumbent up by 3 percentage points. That’s a lot of votes, certainly more than the margin of victory in a tight race. And these results aren’t based on just a handful of games or political seasons; the data were taken from 62 big-time college teams from 1964 to 2008.

And Andrew Gelman signs off on it.

I took a look at the study (I felt obliged to, as it combined two of my interests) and it seemed reasonable to me. There certainly could be some big selection bias going on that the authors (and I) didn’t think of, but I saw no obvious problems. So for now I’ll take their result at face value and will assume a 2 percentage-point effect. I’ll assume that this would be +1% for the incumbent party and -1% for the other party, I assume.

Let’s try this:

  1. Incumbents have an advantage on average.
  2. Higher overall turnout therefore implies a bigger margin for the incumbent, again on average.
  3. In sports, the home team has an advantage on average.
  4. Conditions that increase overall scoring amplify the advantage of the home team.
  5. Good weather increases overall turnout in an election and overall scoring in a football game.

So what looks like football causes elections could really be just good weather causes both.  Note well, I have not actually read the paper but I did search for the word weather and it appears nowhere.