Scorecasting is a non-fiction book by Tobias Moskowitz and L. Jon Wertheim. Moskowitz is an economist at the University of Chicago, and Wertheim is a regular contributor to Sports Illustrated.
The book examines a number of well-accepted “truisms” from the sporting world, and uses data to examine their veracity and try to figure out why they are happening. Things like, what really causes the home field advantage in sports (the answer may surprise you)? Why are some football coaches more willing than others to “go for it” on fourth down rather than punt the ball, even though the math says they all should do it more? Why are some ethnic groups far more likely to use illegal steroids than others? What kind of logical fallacy does Tiger Woods fall for, the same as everyday golfers? The answers presented are well-presented and convincing. If you’re a “thinking” sports fan, there are lots of subjects in this book to interest you. This book is in many ways similar to Levitt and Dubner’s Freakonomics. I don’t think I’ve ever written about that book, but I also recommend it highly.
The chapter that most interested me was called, “The Myth of the Hot Hand.” All sports fans know that in basketball, sometimes players get “into the zone,” and their teammates keep feeding them the ball so they can score when they are “on fire.” Fans know this. Players know this. Sport commentators know this. Except it isn’t true.
Streaks definitely happen, but at any point in the streak (say after a player has made three shots in a row), that player is neither more nor less likely to make it four in a row than he normally is. They checked data from years of games in all kinds of ways (i.e. two in a row, three in a row, four in a row, etc.), and they could find no evidence that the presence of a streak was a good predictor over what’s going to happen next.
The book suggests that it can be a smart bet to bet against the streak. Although the book doesn’t go into details about this, I want to amplify on it because most of my readers are video poker players rather than sports bettors, and some of the concepts aren’t clear. Suppose the New England Patriots have won five games in a row, and they are scheduled to play the Denver Broncos, who have lost four games in a row. Suppose the “fair” odds are that the Pats should win 60% of the time and the Broncs should win 40% of the time.
The money line in Vegas for this fair bet should be 150 — meaning that Patriot bettors need to put up $150 to win $100 and Bronco bettors put up $100 to win $150. The way the sports books make money is to set the line at +140 (betting on Denver) and -160 (betting on New England), so no matter which team you like, you’re taking slightly the worst of it.
The book points out that in this situation, bettors tend to bet more on New England because of the streaks. The line may well move to +210/-180 as the sports book try to get similar amounts of money on both sides of the bet. In this case, the smart money should be on Denver. While a fair $100 bet would give you $150 when you win, under the circumstance described here you’ll be paid $180, rather than $150. This doesn’t at all affect your odds of winning. You’re still a 60-40 underdog. It merely affects the amount you’re paid when you win. Since most of us aren’t capable of exactly determining the “fair” odds, if we always bet against this kind of streaks, we are likely getting a better bet than if we bet with the streak.
In addition to the sports betting application, the reason this interested me is that I’ve been struggling for years to explain this concept to video poker players. Many players keep insisting that the way to gambling success is to “ride the hot streak” or to “bet more when you’re winning.” These are totally nonsensical, of course, but a large number of players believe them. Another way this fallacy appears is that players change games or machines when they are losing. They believe that if they’ve lost over the previous fifteen minutes that they will continue to lose unless they change something. This is also a totally nonsensical, yet very common, way of thinking.
The book describes this as, “Why do we attribute so much importance to ‘sports momentum’ when it’s mostly fiction? Psychology offers an explanation. People tend to ascribe patterns to events. We don’t like mystery. We want to be able to explain what we’re seeing. Randomness and luck resist explanation. We’re uneasy concluding that ‘stuff happens’ even when it might be the best explanation. What’s more, many of us don’t have a firm grasp of the laws of chance.”
I couldn’t have said it better myself. So I won’t even try.