In part one yesterday, we looked at stats of the Boston Red Sox bullpen, a typical example of baseball’s tendency to find special cause in just about anything. The Boston Globe article on which these two columns are based has been a gold mine for teaching many useful, basic concepts about variation. Today we’ll continue the analysis with a closer focus on common cause.

Once again, for those of you who aren’t interested in the statistical mechanics but want to be aware of how this type of analysis can drastically change one’s thinking, just skip to the bottom-line conclusions where indicated. For my non-U.S. readers, I hope you’ll be able to follow the analysis philosophy and see parallels to your favorite sports and news articles.

Any italics in direct quotes are mine, and if I make comments within a quote, I show that by inserting [DB:...].

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