Golf Analytics

How Golfers Win

Predicting Performance based on the Previous Weekend is Hard

Possibly the most overused idea among those involved in predicting golf is that a player’s performance the previous week’s tournament holds a lot of predictive power over their performance in the current tournament. Golfers who win are said to be “in form”, while those who struggle and miss the cut are said to be struggling with their game. However, there’s never been any evidence provided by anyone that the prior week should be factored into a prediction about the following week.

To examine whether this is actually a thing I gathered performance data from the last ten weeks of PGA tournaments (AT&T to Deutsche Bank) from a sample of over 300 golfers. If a golfer played in consecutive weeks, I added his rounds to the sample. In the end I had 497 pairs of prior week->following week data.

The results weren’t exactly promising for “in-from” advocates. The correlation between week 1 and week 2 was only R=0.19. This means if you only knew the performance of a golfer in the prior week, you would predict the following week by regressing that performance over 80% towards the mean (which was -0.07 for the sample).

Now, perhaps there is a prior week effect, but it only appears when you factor underlying skill into the regression. To test this, I took each golfer’s weighted two year Z-Score from the week following the Travelers Championship and added that variable to the prior week variable to predict the following week. The results follow:

R=0.32, y=(0.94*SKILL)+(.10*PRIOR)+0.16, both variables were statistically significant at the 95% level

However, this indicates that underlying skill is over nine times more important than the prior week in predicting the following week. In other words, to predict how a golfer will perform the following week, look at how he’s performed in the last two years rather than just how he played the week earlier.

One response to “Predicting Performance based on the Previous Weekend is Hard

  1. Pingback: Bayesian Prediction of Golfer Performance (Individual Tournament) | Golf Analytics

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