It Turns Out The Hot Hand Effect Is Real In Basketball, And Stat Geeks Have Been Wrong For Decades
Stat geeks love to point out how the concept of getting hot is meaningless in sports. Just because Carmelo Anthony hit his last five shots, they argue, does not mean he is any more likely to hit his next shot, no more than a coin that landed heads five times in a row is more likely to land on heads again. The so-called hot hand fallacy was not only debunked by a 1985 paper that found no positive correlation between successive shots by players on the Philadelphia 76ers, as well as several subsequent studies, but also supported by established psychological tendencies of people to see patterns in random data.
They repeated this argument despite the insistence of athletes, commentators, fans, and coaches that the hot hand effect was real.
Considering this history, it was surprising when new research, presented last week at the MIT Sloan Sports Analytics Conference, showed that the hot hand effect was real.
Harvard researchers Andrew Bocskocsky, John Ezekowitz and Carolyn Stein theorized that we could only truly understand shooting trends by considering shot difficulty, and they were able to do this using advanced play-tracking data from the NBA's new SportVu camera system.
What they found is that players who have made an unusually high number of their last four shots will have a 1.2 to 2.4% greater likelihood of making their next shot than normal when accounting for shot difficulty.
At the same time, they provided evidence for another effect that often counteracts and obscures the hot hand effect. Players who are feeling hot are more likely to attempt unnecessarily difficult shots, pushing down their field goal percentage to normal levels or even lower.
It's not a huge statistical breakthrough as far as strategy, though ESPN's Beckley Mason points out that players and coaches may benefit from being more aware of their own decision making.
It is a big deal as far as putting overzealous stat geeks in their place.
As the paper concludes:
For thirty years, the empirical consensus that the "Hot Hand" in basketball is a fallacy of the human mind has been confirmed time and again. In the same way that evolutionary biologists might regard creationists as completely misguided, economists, psychologists and statisticians have viewed the persistent belief in the Hot Hand as entirely fallacious. Amos Tversky, co-author of the canonical paper on the subject, typifies this view when he says, "I've been in a thousand arguments over thi s topic, won them all, but convinced no one" (Bar - Eli, Avugos and Raab, 2006). ... At the very least, our findings cast doubt on the overwhelming consensus that the Hot Hand is a fallacy.
In fact, the hot hand fallacy wasn't the only cherished statistical concept challenged at Sloan.
Radical high school football coach David Kelley also presented data showing that drives after turnovers are almost twice as likely to produce points - in other words, that the much-maligned concept of momentum (which is very similar to the hot hand effect) could actually be true.