Monday, January 28, 2019

The So-Called Sports Illustrated Jinx

The Sports Illustrated Jinx is the notion that being featured on the cover of SI leads to bad-luck that negatively affects future performance.

Examples of the Sports Illustrated Jinx (Wikipedia excerpts):
“May 26, 1958: Race car driver Pat O’Connor appears on the cover of the magazine. He dies four days later on the first lap of the Indianapolis 500.

August 7, 1978: Pete Rose appears on the cover the same week that his 44-game hitting streak ended.

May 8, 1989: Jon Peters, of Brenham High School in Texas, sets the national high school record for games won by a pitcher, with a 51-0 record. The next game after his cover appearance, he loses for the first (and only) time of his high school career.

In November 2007, Kerry Meier of the Kansas Jayhawks appeared on the cover with the caption “Dream Season (So Far)” at the time when the Jayhawks’s record was 11-0. In their next game they lost to their arch rivals, the Missouri Tigers, 36-28, ending the Jayhawks’s perfect season.

November 9, 2009: Iowa’s Derell Johnson Koulianos appears on the front cover with the words “Still Perfect.” The Hawkeyes lost to Northwestern two days before the issue date, ending the longest winning streak in school history.”

Can the SI Jinx be explained by a statistical concept? Statistical regression to the mean indicates poor performance is typically followed by better performance, while exceptionally good performance is typically followed by decreased performance. How does this apply to the SI Jinx?

"It does not take much statistical sophistication to see how regression effects may be responsible for the belief in the Sports Illustrated jinx. Athletes’ performances at different times are imperfectly correlated. Thus, due to regression alone, we can expect an extraordinary good performance to be followed, on the average, by a somewhat less extraordinary performance. Athletes appear on the cover of Sports Illustrated when they are newsworthy- i.e., when their performance is extraordinary. Thus, an athlete’s superior performance in the weeks preceding a cover story is very likely to be followed by somewhat poorer performance in the weeks after. Those who believe in the jinx, like those who believe in the hot hand, are mistaken, not in what they observe, but in how they interpret what they see. Many athletes do suffer deterioration in their performance after being pictured on the cover of Sports Illustrated, and the mistake lies in citing a jinx, rather than citing regression as the proper interpretation of this phenomenon." Gilovich, 1991, p.26

The term regression to the mean was discovered and coined by Francis Galton in the late nineteenth century (Kahneman, 2011).  The term might be hard to understand, as causal reasoning often overrides this type of statistical thinking. It might be a hard concept to understand for those without training in stats. Kahneman reports this sort of thinking doesn't come naturally and often leads to confusing outcomes. "The statistician David Freedman used to say that if the topic of regression comes up in a criminal or civil trial, the side that musty explain regression to the jury will lose the case. Why is it so hard? The main reason for the difficulty is a recurrent theme of this book: our mind is strongly biased toward causal explanations and does not deal well with 'mere statistics" (Kahneman, 2011, p.182).

References available upon request.