Wednesday, July 30, 2008

The Pre-Game Show

Today we were getting ready for tonight's Mud Hens game. I passed out scoresheets and we talked about how to keep score. I'll be sitting in section 115 with a Phillies cap -- I can help you if you need help scoring particular plays.

In Chapter 7, we are talking about statistical inference. Specifically, how can we learn about a player's ability given his performance.

We did a silly exercise to illustrate the distinction between ability and performance. Suppose the manager Casey has seven types of hitters in his dugout -- a couple of hitters are great in getting on-base and their ability is p=.5; two other players have p=.45; two other players have p=.4, ..., and two crummy players are weak in getting on-base and p=.2. Suppose Casy chooses a player at random and has that player bats 20 times and records X = number of times on base.

We repeat this exercise 10,000 times and we categorize all hitters by their ability (value of p) and their performance (value of X). I passed out the table of counts. Given a particular batting performance, say 8 out of 20 on-base, I showed how you can compute the probabilities of the player having different batting abilities.

Tonight we'll keep score, compute a couple of OBPs and SLGs and be on the lookout for lucky plays.

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