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ESPN Magazine recently had a "conspiracy theories" issue, in which it explored (among other things) the long-held, popular theory that basketball is fixed. Coll

ESPN Magazine recently had a "conspiracy theories" issue, in which it explored (among other things) the long-held, popular theory that basketball is fixed. College basketball, in particular. IIRC, the preconditions for a fixed game tended to be: - Non-tournament, regular season play (b/c not as many bettors and media would be paying attention) - The favorite team is favored by 11 or more points - The favorite team is dominated by one or two very strong players If one player controls his team's play, and he's favored by 11+ points, he has the incentive, the ability, and the margin to shave points without risking losing the game. With a smaller point spread, on the other hand, it's too risky. For reasons I can't recall, an 11-point spread was the magic number. It provided just enough cushion to cover shaving, without jeopardizing the nominal win. When analysts looked at the history of games that met these criteria, they found consistently abnormal distributions of outcomes in favor of the winning team, but just south of the spread. They estimated that about 3-4% of games in the study sample are quite likely to have been fixed. At any rate, it would be interesting to see bigger data sets plied for this sort of thing.

untouchable 13y ago
This article? http://espn.go.com/nba/story/_/id/10545306/nba-most-conspiracy-theories-sports-espn-magazine http://espn.go.com/nba/story/_/id/10545306/nba-most-conspira...
- jonnathanson 13y ago
  It was that issue, but a different article, about an alleged point-shaving operation involving the University of San Diego. EDIT: Correction noted.
  - jasondemeuse 13y ago
    Small correction, but it was actually University of San Diego. The article about Brandon Johnson and the point shaving is here: http://espn.go.com/mens-college-basketball/story/_/id/10545391/former-assistant-tj-brown-brandon-johnson-center-university-san-diego-point-shaving-scandal-espn-magazine http://espn.go.com/mens-college-basketball/story/_/id/105453...
T-hawk 13y ago
An alternative explanation is simply that a lead of 11 points tends to dwindle because the good players relax at less than maximum effort while on the court when the win is in hand. That would be statistically indistinguishable from intentional point shaving. (In fact, it IS emergent point shaving, just without any sinister motive.) This also explains the postseason discrepancy, that players wouldn't let up in a tournament game. The correct resolution would be for the pregame betting line to account for that tendency, taking into account the favorite's likelihood to coast during garbage time.
- dhimes 13y ago
  Definitely good points. Down by 11 points with little time left a losing team takes risks- such as fouling in shooting situations- that the winning team doesn't take. The winning team tends to stall. Of course, it may also just be hard to pick an 11 point spread. I wonder how many won by more than the spread?
- jonnathanson 13y ago
  It's certainly plausible, but in theory, the point spread is supposed to account for that effect (among all other natural factors involved in play). As you suggest in your second paragraph. Intellectually, of course, I tend to assume the Occam's Razor solution (i.e., natural variance and other effects over deliberate fixing) in most cases. I'm not one for conspiracy theories as a first line of thinking. And I think a bigger sample size is needed to begin with. Another thing to keep in mind is that -- at least in theory -- players aren't supposed to be cognizant of a point spread when playing. If we wanted to detect deliberate point shaving, we'd need to look at instances where the player behaved as if he was very aware of the spread and was actively trying to manage it. For example, he actively takes possession of the ball and runs out the clock, misses easy shots, passes into heavy coverage, and then reverses course to correct when/if he goes too far. Basically, the behavior of someone who's trying hard in either direction, as opposed to someone who just tries hard to secure the win and then lets up.
im3w1l 13y ago
I wonder if such a small effect size is really statistically significant, especially if you correct for the multiple hypotheses that are implicit in that specific a choice of subgroup...

untouchable 13y ago

This article? http://espn.go.com/nba/story/_/id/10545306/nba-most-conspiracy-theories-sports-espn-magazine http://espn.go.com/nba/story/_/id/10545306/nba-most-conspira...

jonnathanson 13y ago
It was that issue, but a different article, about an alleged point-shaving operation involving the University of San Diego. EDIT: Correction noted.
- jasondemeuse 13y ago
  Small correction, but it was actually University of San Diego. The article about Brandon Johnson and the point shaving is here: http://espn.go.com/mens-college-basketball/story/_/id/10545391/former-assistant-tj-brown-brandon-johnson-center-university-san-diego-point-shaving-scandal-espn-magazine http://espn.go.com/mens-college-basketball/story/_/id/105453...

T-hawk 13y ago

An alternative explanation is simply that a lead of 11 points tends to dwindle because the good players relax at less than maximum effort while on the court when the win is in hand. That would be statistically indistinguishable from intentional point shaving. (In fact, it IS emergent point shaving, just without any sinister motive.) This also explains the postseason discrepancy, that players wouldn't let up in a tournament game. The correct resolution would be for the pregame betting line to account for that tendency, taking into account the favorite's likelihood to coast during garbage time.

dhimes 13y ago
Definitely good points. Down by 11 points with little time left a losing team takes risks- such as fouling in shooting situations- that the winning team doesn't take. The winning team tends to stall. Of course, it may also just be hard to pick an 11 point spread. I wonder how many won by more than the spread?
jonnathanson 13y ago
It's certainly plausible, but in theory, the point spread is supposed to account for that effect (among all other natural factors involved in play). As you suggest in your second paragraph. Intellectually, of course, I tend to assume the Occam's Razor solution (i.e., natural variance and other effects over deliberate fixing) in most cases. I'm not one for conspiracy theories as a first line of thinking. And I think a bigger sample size is needed to begin with. Another thing to keep in mind is that -- at least in theory -- players aren't supposed to be cognizant of a point spread when playing. If we wanted to detect deliberate point shaving, we'd need to look at instances where the player behaved as if he was very aware of the spread and was actively trying to manage it. For example, he actively takes possession of the ball and runs out the clock, misses easy shots, passes into heavy coverage, and then reverses course to correct when/if he goes too far. Basically, the behavior of someone who's trying hard in either direction, as opposed to someone who just tries hard to secure the win and then lets up.

im3w1l 13y ago

I wonder if such a small effect size is really statistically significant, especially if you correct for the multiple hypotheses that are implicit in that specific a choice of subgroup...