Clemens-ometrics

Are you sick of the Roger Clemens-Brian McNamee flap? I am, but the infusion of some new statistical analysis has renewed my interest in the issue. A group of statisticians and an economist at the University of Pennsylvania have used some pretty simple analysis to address (and refute) Clemens' lawyers' claims that the statistical record exonerates Roger from allegations of taking performance enhancing drugs.

The take home point of the whole exercise is simple. The statisticians allege that the analysis in the "Clemens Report" is highly prone to selection bias: the "control group" for Roger Clemens is comprised of freaks of nature like Nolan Ryan. This new analysis looks at a different control group (all pitchers who make a given number of appearances over a reasonably long career) and finds that Clemens is certainly an outlier. Obviously, this does not suggest that Clemens used performance enhancers anymore than it implicates Nolan Ryan, but it does suggest that Clemens statistical record does not hold him above suspicions in these investigations, which is what the pitchers' lawyers are arguing.

For more information, see here. The Freakonomics blog has a guest post by economist Justin Wolfers, one of the analysts on the study, talking about the whole exercise. Also, I heard sometime before that statistical methods were used to analyze steroid use among hitters, as well. I have not been able to find any reliable links on that. If you have one, please post it.