Saturday, June 20, 2009
Outthinking ourselvesPosted by Colin Wyers
One of the miracles of the Internet is that so much is preserved for posterity that otherwise would just get washed away. Here's an oldie but goodie from Ron Shandler, talking about the way he adjusts his projections:
As an example, let's look at Pujols. After hitting 37, 34, 43, and 46 HRs, his baseline projection called for 42, which represented a normal regression to the mean. However, our flags pointed out consistent upward trends in contact rate, fly ball ratio, batting eye and a second half surge in his power index. Add in his alleged age (25) and a reliability rating of 94, and all signs pointed north for his power trend to continue. Our projection now calls for 50 HRs.
Why 50? I believe it is reasonable to expect Pujols to maintain his second half PX level for a full six months, given the trends in his skills. For some people, it might take a moment to accept 50, but the more you look at it, the more it passes the eyeball test. This is a player with no true comparables in history. All we have is our eyeballs and a general idea of what makes sense. Fifty makes sense to me.
That's all well and good, except Albert Pujols hit 41 home runs that year. For those of you keeping score at home, that's Regression To The Mean 1, Shandler 0.
Colin Wyers knows exactly how much of a nerd he is. He is very interested in hearing about any other concerns you may have; you can reach him by e-mail, and he will try his best to respond in a timely fashion. He also blogs at Statistically Speaking.