Tracking Live Win Expectancy

I’ve been working on a win expectancy tracker for IndyCar similar to the one FanGraphs uses for baseball. Based on the driver’s current position and how much of the race is completed, it calculates the percent chance he will win the race — using historical data from the 2013-2016 seasons.

It works by finding the win percentage of drivers who were in similar situations in the past. For example, if a driver is running in second place with 60 percent of the race completed, he has a 13.9 percent chance of winning the race. That’s based on five drivers in the database (36 races as of writing) being in second place with 60 percent of the race completed going on to win the race.

If a driver has a 23 percent chance of winning, that means 23 percent of drivers in the same situation went on to win the race.

Besides telling how likely each driver is to win the race, it’s also beneficial to see which drivers need to make big strategy moves to have a shot at winning. If a driver only has a 13 percent chance of winning, maybe he’ll want to go off strategy and hope to get lucky with a caution. Win expectancy is also interesting to look back at after the race to see when the big moments of the race were.

It’s important to note that win expectancy doesn’t care about who the drivers are, the prevalence of cautions at certain tracks, or anything else of that nature. So it’s a bit of an oversimplification, but a useful one nonetheless. It reports the long term averages for running position and the amount of the race completed.

Road/street course results are separate from oval results, but so far only the former is done.

I’ll be tweeting out live win probabilities during races and also including them on the site.

by Drew

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s