What did we learn today?

1. It is tough to show a youtube streaming video when the wireless connection is slow. We watched part of a Ken Burns documentary segment about the 1927 Yankees. This team featured two of the greatest sluggers in history, Babe Ruth and Lou Gehrig.

2. We talked about the important hitting statistics that you should know how to compute from the basic counting stats (H, 2B, 3B, HR, AB, BB): AVG (batting average), OBP (on-base percentage, and SLG (slugging percentage).

3. We compared two great modern pitchers Greg Maddux and Roger Clemens. We focused on the season WHIP values for the two pitchers. (WHIP is the average number of hits and walks allowed per inning.)

Here is our method:

-- we constructed back-to-back stemplots of the WHIP values for the two pitchers

-- we summarized each collection of WHIPS by a five-number summary. This summary gives us a measure of average (the median) and a measure of spread (the IQR)

-- we compared the spreads of the two batches -- the spread of Maddux's WHIPs is about the same as the spreads of Clemens' WHIPs

-- IF the spreads of the two batches are roughly equal (as they are here), we can compare batches by comparing the medians.

What did we learn in this comparison?

-- Maddux, on average, had a slightly smaller WHIP than Clemens.

-- If we look more closely, I think we would see that Maddux was a better pitcher than Clemens.

at his peak -- Maddux had several outstanding pitching seasons when he was 28 or 29.

-- But overall both pitchers were strong over long periods of time.

## Monday, July 7, 2008

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