Thursday, September 19, 2013

Predicting the Chase Champion: These Numbers Still Say Jimmie Johnson is Leading the Chase

Predicting the Chase Champion: These Numbers Still Say Jimmie Johnson is Leading the Chase

Only one question matters now: “Who will win the Chase?”

We can accurately predict the likelihood of each driver winning the title, based on two factors:
(1) The current points standings
(2) Each driver’s full set of finishes this season.

We can also predict how many points the eventual champion will have.

More interestingly, we can update these predictions after each Chase race, based on the latest results and updated standings. This will show us exactly how much a driver’s title hopes changed, in percentage terms, from race to race.

Here were the chances for each driver to win the title, before the Chase started:

Jimmie Johnson, entering the Chase, was the model's favorite driver, due to the strength of so many upfront finishes in 2013. Remember, the percentage likelihood of winning the title may not match up exactly with the points standings. That’s because this model combines the points standings with the expectation of each driver’s performance.

Ryan Newman and Jeff Gordon, the two drivers who were added to the Chase after the fact, have very low odds of winning a title – notice them near the bottom of the chart. NASCAR did not significantly reduce the odds of the main contenders by including these two in the Chase.

Using the same prediction model as above, we can now shift our focus from the winning driver to the number of points needed to win.  It’s all calculated as part of the same process, simulating thousands of possible race results. Here is the expectation, prior to the Chase starting, of how many points the champion will have:

As the chart shows, we should expect the champion to end with a points total around 2360-2380. Compare that with what happened in the past two seasons: Tony Stewart finished with 2403 points in 2011 and Brad Keselowksi had 2400 points in 2012. If somebody gets on a hot streak during the Chase, you will see this chart shift to the upside.

We will be updating both charts weekly so you can see how the field fares race by race.

Now that the Chase has begun, here are the updated title chances after Chicago:

The winner, on the race track and in the model, is Matt Kenseth. His title chances leaped to 25% from 14% due to his win and increased points lead. Jimmie Johnson, at 26%, still has a slight edge over Kenseth though. Remember, despite Kenseth's points lead, the model currently prefers Johnson due to Kenseth's high number of poor finishes this year. Kenseth can change this prediction by consistently finishing up front, breaking the pattern of his early-season troubles.
Joey Logano and Dale Earnhardt, Jr. hold down the bottom of the chart, because of DNFs at Chicago. Their equipment failures and mediocre 2013 performance may have already sealed their fates: their title chances are currently below 0.1%.

Finally, our expected championship point total predicts the winner to be near 2360-2400 points.

Check in after this weekend’s race to see updated numbers.