Well: Winning Streaks in Sports

Phys Ed

Gretchen Reynolds on the science of fitness.

Winning streaks in sports may be more than just magical thinking, several new studies suggest.

Whether you call them winning streaks, "hot hands" or being "in the zone," most sports fans believe that players, and teams, tend to go on tears. Case in point: Nate Robinson's almost single-handed evisceration of the Miami Heat on Monday night. (Yes, I am a Bulls fan.)

But our faith in hot hands is challenged by a rich and well-regarded body of science over the past 30 years, much of it focused on basketball, that tells us our belief is mostly fallacious. In one of the first and best-known of these studies, published in 1985, scientists parsed records from the Philadelphia 76ers, the Boston Celtics and the Cornell University varsity squad and concluded that players statistically were not more likely to hit a second basket after sinking a first. But players and fans believed that they were, so a player who had hit one shot would be likely to take the team's next, and teammates would feed this "hot" player the ball.

Other studies showed that fans supported and bet on teams that they thought were on a hot streak, even though these bets rarely paid off. Our belief in them revealed how strongly humans want to impose order and meaning on utterly random sequences of events.

Now, however, some new studies that use huge, previously unavailable data sets are suggesting that, in some instances, hands can ignite, and the success of one play can indeed affect the outcome of the next.

In the most wide-ranging of the new studies, Gur Yaari, a computational biologist at Yale, and his colleagues gathered enormous amounts of data about an entire season's worth of free throw shooting in the N.B.A. and 50,000 games bowled in the Professional Bowlers Association. Subjecting these numbers to extensive (and, to the layperson, inscrutable) statistical analysis, they tried to determine whether the success or failure of a free throw or a bowling frame depended on what had just happened in the competitor's last attempt. In other words, if someone had just sunk a free throw or rolled a strike, was the person more likely to succeed immediately afterward? Or were the odds about the same as tossing a coin and seeing how it landed?

In these big sets of data, which were far larger than those used in, for instance, the 1985 basketball study, success did slightly increase the chances of subsequent success — though generally over a longer time frame than the next shot. Basketball players experienced statistically significant and recognizable hot periods over an entire game or two, during which they would hit more free throws than random chance would suggest. But they would not necessarily hit one free throw immediately after the last.
Similarly, bowlers who completed a high-scoring game were more likely to roll strikes in the next game. But a strike in one frame of each game was not statistically likely to lead to a strike in the next frame.

Hot streaks have some relevance in volleyball as well, as a 2012 study helpfully titled "The Hot Hand Exists in Volleyball" explores. Researchers at the German Sport University in Cologne examined match results for 26 elite volleyball players and identified statistically meaningful scoring streaks among half of them. The researchers also found that when a players got hot, teammates and coaches responded almost immediately in ways that moved the ball to the streaking player, increasing the team's likelihood of winning.

But if winning streaks have some rational basis, then by inference so would losing streaks, which makes the latest of the new studies, of basketball game play, particularly noteworthy. In that analysis, published last month in the journal Psychological Science, Yigal Attali, who holds a doctorate in cognitive psychology, scrutinized all available shooting statistics from the 2010-11 N.B.A. season.

He found that a player who drained one shot was more likely than chance would suggest to take the team's next shot — and also more likely than chance would suggest to miss it.

Essentially, he found that in real games, players developed anti-hot hands. A momentary success bred immediate subsequent failure.

The reason for this phenomenon might be both psychological and practical, Dr. Attali wrote; players seemed to take their second shots from farther out than their first ones, perhaps because they felt buoyed by that last success. They also were likely to be defended more vigorously after a successful shot, since defenders are as influenced by a belief in hot hands as anyone else.

But what the findings underscore, more subtly, is that patterns do exist within the results. The players were more likely to miss after a successful shot. And this anti-hot hand phenomenon, said Dr. Yaari, who is familiar with the study, was itself a pattern. "It is not completely random and independent" of past results, he said.

These new studies do not undermine the validity of the magisterial past research on hot hands, but expand and augment it, Dr. Yaari and the other authors say, adding even more human complexity. Yes, we probably imagine and desire patterns where they do not exist. But it may be that we also are capable of sensing and responding to some cues within games and activities that are almost too subtle for most collections of numbers to capture.

"I think that our minds evolved to be sensitive to these kinds of patterns," Dr. Yaari said, "since they occur frequently in nature."

And that is enough encouragement for me to believe that, against all rational expectations, the Bulls will carry the series against Miami. They're hot.

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