Wednesday, December 19, 2007

Milwaukee newspaper article on steroids and performance

This article, from the Milwaukee Journal-Sentinel, professes to be "the first statistical analysis of player performance for those named in the 409-page [Mitchell] report." But it's really just a bunch of anecdotes; there's little useful analysis there at all.

The authors start by telling us that of the ninety players named in the report, 33 "immediately improved in the first season [after starting to juice] compared with their career averages." So, what does that mean? Wouldn't you expect that, even without steroids, 45 of the 90 would improve, and the other 45 wouldn't? Are they trying to tell us that steroids actually *hurt* performance? Probably not, but we don't know for sure, because, having given us this statistic in the second paragraph, they never mention it again.

Then, they immediately tell us that 27 hitters and 19 pitchers "raised their statistical performances." That's 46 players, not 33. Why the difference? They don't say, but, based on an
accompanying chart, it looks like the extra 13 players are those who improved in the second season, but not the first. And that 46 out of 90 is again very low. If seasons were random, then you'd expect 75-80% of subsequent two-year records to show at least one improvement, wouldn’t you?

Perhaps the difference in both cases is due to mostly *older* players turning to performance-enhancing drugs; older players tend to be on the decline. But without a control group, how do we know whether these numbers are actually different from the norm?

The authors go on to tell us that "thirty players used performance-enhancing drugs only in their last year or two in the big leagues or after they had slipped back to the minor leagues." I'd have phrased it a different way: that thirty players dropped out of the major-leagues within two years after first starting to take PEDs. That would suggest that maybe the steroids didn’t work, wouldn’t it? The article says that "many of these players tried to hang on to the tail end of their careers," but, again, we don't have a control group. (And perhaps some of these players didn't know it was "the tail end of their careers" when they started on the drugs; it's not like baseball players have a best-before date tattooed on their body.)

Then, the article says that "eight of the 33 all-stars named in the report were selected only in seasons after they reportedly began using performance-enhancing drugs." Is that significant? Again, how many were selected only in seasons after they changed teams or got married? Maybe honeymoons are also performance-enhancing.

And, finally, the authors note that some players signed huge contracts after starting to use PEDs. They didn't mention that some players also signed huge contracts after NOT starting to use PEDs.

A real statistical analysis would take an unbiased prediction of the players' next season – Marcels, or PECOTAs – and see if those players outperformed. It would be interesting to find out if that was actually the case, and to what extent.

UPDATE: J.C. Bradbury links to a similar comment today.

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At Thursday, December 20, 2007 11:59:00 AM, Anonymous Anonymous said...

It would be interesting, and would lead us to what we expect to find, meaning that no newspaper will carry the article.


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