Barry Bonds and the Placebo Effect
Why Bonds won't break the homer record and the placebo effect might be bunk.
One question still needs to be answered: How many home runs will Barry Bonds hit this year? That is, how strong is regression to the mean? If our discussion above is correct, then hitters who lead the major leagues in home runs at the All-Star break should tend to decline in the second half of the season. Thanks to David Vincent of the Society for American Baseball Research, we have those numbers in hand for every non-strike season since 1933. (Click
Jordan Ellenberg is a professor of mathematics at the University of Wisconsin. His book How Not To Be Wrong is forthcoming. He blogs at Quomodocumque.