The DH Redux: Japan June 7, 2010
Posted by tomflesher in Baseball.Tags: Baseball, baseballguru.com, designated hitter, Japan, NPB, OBP, regression, replication
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In an earlier post, I analyzed team-level data from Major League Baseball to determine the size of the effect that the Designated Hitter rule has on on-base percentage. The conclusion I came to was that, if the model is properly specified, the effect of the designated hitter rule is about .008 in on-base percentage. If the reasoning was correct, then when there are no other confounding variables, the effect should be similar in size for any other professional league.
Of course, the other major professional league is Nippon Professional Baseball, the major leagues of Japan. Since it produces players at a level similar to MLB, and the other factors are similar – the DH rule was adopted in 1975 by one, but not both, of the two major leagues – NPB is an ideal place to try to test the model I specified in this post.