STATism: An Alternative to Democracy

I want to feel young again, so I designed a wildly unrealistic form of government that will likely never be implemented. Democracies and democratic republics (“democracies”) have been around for thousands of years. Counting the votes for each side isn’t a bad way to decide who should have power, but with the latest advances in math and machine learning, we should be able to do better. To make things confusing for libertarians, I’m going to call my system “STATism.”

I encourage you to read this as political science fiction rather than as a serious proposal. Continue reading →

Predicting NFL Scores: A Bayesian Approach

With the 2013 football season behind us, I’ve been spending my weekends developing a Bayesian model of the NFL with my college friend and UT math phd candidate Chris White.

To generate a Bayesian model, one first comes up with a parametric model that could generate the observed data. For simple problems, one uses Bayes rule to calculate the probability of parameters equaling certain values given the observed data. For complicated models, this is an extremely complicated task, but there are some monte carlo methods, such as Gibbs Sampling, which produce satisfactory approximations of the actual distributions. There are R packages available that make Gibbs Sampling fun.

I want to touch on many of these topics later in more in-depth posts, but first, here’s some results.

As of the end of the 2013 regular season, this is how our model ranked the NFL teams.

NFL Fig 1

These are the mean estimates of our Bayesian model trained on the 2013 NFL regular season. Our model predicts that, on a neutral playing field, each team will score their oPower less their opponent’s dPower. The former is the mean of a poisson process and the latter is the mean of a normal distribution. Homefield advantage is worth an additional 3.5 net points, most of which comes from decreasing the visitor’s score.

So we predict the Rams would beat the Lions by a score of 27.4 to 25.8 on a neutral field. Since we know the underlying distributions, we can also calculate prediction intervals.

Here’s the same model trained on both the regular season and the post-season. The final column shows the change in total power.

NFL Fig 2

I have a list of ways I want to improve the model, but here’s where it stands now. Before next season, I want to have a handful of models whose predictions are weighted using a Bayesian factor.

I’m very excited about this project, and I’ll continue working on it for a while.