Wednesday, September 4, 2013

Why Dale Jr should have a 100% Chance of Making the Chase (and Keselowski 0%)

With one race to go before the Chase starts, only 6 spots in the top 10 have been clinched. That leaves 4 more spots still to be filled, with these 10 drivers mathematically eligible for them:

In today’s post, we look at these 10 eligible drivers, and using a simple forecasting method, we predict the chance each driver has of making the top 10.

For those of you who are too eager to wait, here is the final answer:

How did we arrive at these percentages?

One way to forecast how these drivers will perform this weekend is to consider their performance in the first 25 races this year.  This is a large enough sample size to suggest the full range of each driver’s results, based on their circumstances, equipment, and team quality this season. The table below shows the number of points scored by each driver in each race this season. For example, Dale Earnhardt, Jr. scored 42 points in the first race this season, 40 points in the second race, and 37 points in the third race, a sizzling start to the season.

Let’s assume this weekend’s Richmond race will have a similar profile to one of the previous 25 races this season.  In that case, we have 25 possible outcomes for what the points standings will be following the race, by adding the current points of each driver to the 25 theoretical results. The "T" in front implies the theoretical outcomes that could occur, so "T9" is how many points each driver would have if the results from the ninth race this season are repeated this weekend.

With these 25 possible outcomes, we can now rank the points standings for these 10 drivers.  Remember that only the best 4 drivers from this group will make the top 10. The "R" implies what the rankings would be based on our theoretical results, so "R9" is the ranking that would happen if the results from the ninth race this year are duplicated.

Based on these rankings, we can count how many times each driver finishes in the top 4 of this group, and divide by 25 to get his percentage chance of making the Chase:

So there you have it: based on the previous races this season, Dale Earnhardt Jr. would qualify for the Chase every time.  On the other hand, Brad Keselowski and Jamie McMurray would not qualify, given how they've performed in their previous 25 races.

Notice one interesting observation that emerges from the data: even the narrowest of points leads can translate into a significant edge in making the top 10. For example, Kurt Busch has a small 6 point lead over Jeff Gordon, but that’s worth an additional 16% chance of making the top 10.

The method we've seen here is just one approach to calculating the odds of making the top 10.  This approach is intuitive because it's based on real performance data from the season, and gives you a quick sense for what we should expect from each driver.

All this is good news for drivers like Earnhardt and Joey Logano, who should feel very confident about making the cut.  In contrast, drivers like Keselowski and McMurray will have to pull off their best performances of the year to have any chance of qualifying.  And for the viewing audience, the most interesting battle for the top 10 should be among the three drivers with chances closest to 50%: Kurt Busch, Jeff Gordon, and Kasey Kahne.

And yes, there is one fact we all know is true: anything is possible this weekend.  That's why they run the races while we sit and watch them.

By the way, in case you were wondering, the Richmond race from this spring is race #9. If history repeats itself this weekend, Jeff Gordon would knock Greg Biffle out.