Two Graphs and 665 words that will convince you on Shooting %

Last week Tyler Dellow had a post titled “Two Graphs and 480 Words That Will Convince You On Corsi%” in which, you can say, I was less than convinced (read the comments). This post is my rebuttal that will attempt to convince you on the importance of Sh% in player evaluation. The problem with shooting percentage is that it suffers from small sample size issues. Over small sample sizes it often gets dominated by randomness (I prefer the term randomness to luck) but the question I have always had is, if we remove randomness from the equation, how important of

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Measuring persistence, randomness, and true talent

In Rob Vollman’s Hockey Abstract book he talks about the persistence and its importance when it comes to a particular statistics having value in hockey analytics. For something to qualify as the key to winning, two things are required: (1) a close statistical correlation with winning percentage and (2) statistical persistence from one season to another. More generally, persistence is a prerequisite for being able to call something a talent or a skill and how close it correlates with winning or some other positive outcome (such as scoring goals) tells us how much value that skill has. Let’s look at persistence first. The

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Estimating actual randomness in goal data

If you have been following the discussion between Eric T and I you will know that there has been a rigorous discussion/debate over where hockey analytics is at, where it is going, the benefits of applying “regression to the mean” to shooting percentages when evaluating players. For those who haven’t and want to read the whole debate you can start here, then read this, followed by this and then this. The original reason for my first post on the subject is that I rejected Eric T’s notion that we should “steer” people researching hockey analytics towards “modern hockey thought” in

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Washington’s 2009-10 Shooting Percentage…

Yesterday there was a post on the Behind the Net Blog which discussed the Washington Capital’s 2009-10 even strength shooting percentage of 11.0% and the conclusion was that it must be mostly luck which resulted in a shooting percentage that high.  But was it?  It was noted in the article that in 2007-08 the Capitals shot at 8.1%, in 2008-09 they shot at 8.2% and this season they are shooting at 8.2% again.  So clearly 2009-10 appears to be an anomaly, but was it a luck driven anomaly or something else? Most people in the hockey analysis world have been using

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Do good teams Create Good Luck? (Updated)

(Updated to include 3 seasons of data as I now realize that more luck data was available) The other day there was a post on the Behind the Net Blog which used betting odds to estimate how lucky a team was during the 2009-10 season.  In many ways it is quite an ingenious way to evaluate a teams luck and I recommend those who have not read it go take a look.  Last night I was watching, sadly, the Leafs-Oilers game and thinking about luck in a hockey game and whether a team has any control over the luck they

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