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making probabilistic predictions

Fivethirtyeight.com has an online prediction game for the 2017 NFL season: https://projects.fivethirtyeight.com/nfl-predictions-game/ . Participants make a probabilistic prediction for each game (e.g., Cincinnati has a 59 percent chance of winning against Indianapolis), and after the game has been played, the prediction is scored using Brier scores that are adapted to a -75 to +25 scale. (So that 59 percent prediction yielded +8.2 points when Cincinnati won.) As preparation for learning about probabilities in chapter 6, and just to develop a working familiarity with thinking in terms of probabilities, I’m having my students make predictions each week. (As of right now, they’ve been doing it for five weeks.)

When I gave them the assignment, I emphasized that if they’re not too into football–and some of them are not–then they shouldn’t spend much time on this. It’s not a big part of what we’re doing, but I think just a little bit of time every week making the predictions has to help them understand probabilities better. Of course, the prediction game won’t get them all the way to knowing the probability rules that are in chapter 6, but hopefully it’s a step in the right direction.

These are the directions that I posted for the assignment: NFL predictions game instructions. I gave them the assignment just as we were finishing up chapter 3, and so they did it for several weeks before we got to chapter 6. I’ll have them stop a couple of weeks before the semester ends.

One difficulty with this assignment is that I don’t have an easy way of checking that students have done their predictions each week. But the website works pretty well on phones, so, after three weeks, I had all of the students show me their predictions during my office hours or before or after class (on their phones or on the computer in my office). I used that for the first of two grades that I’ll give them for this. (100 percent just for making predictions each week, and a little bit of extra credit for the students who’s scores were in the top half of the class.)

I emailed Fivethirtyeight and asked about adding a “share my results” feature, which would make the grading much simpler. This was part of the response that I got: “We’d like to add more social features, and maybe private groups so people can create their own leaderboards, but it probably won’t happen this season. We’ll keep it in mind for next year.”