Comments on: Saber-Terms Series: wOBA http://marlinmaniac.com/2009/11/13/saber-terms-series-woba/ A Florida Marlins Blog Fri, 12 Mar 2010 14:31:00 +0000 http://wordpress.org/?v=2.9.1 hourly 1 By: Michael Jong http://marlinmaniac.com/2009/11/13/saber-terms-series-woba/comment-page-1/#comment-446 Michael Jong Sun, 15 Nov 2009 00:09:34 +0000 http://marlinmaniac.com/?p=1166#comment-446 Colin, Thanks for the explanation. I was a bit confused about that. Colin,

Thanks for the explanation. I was a bit confused about that.

]]> By: Colin Wyers http://marlinmaniac.com/2009/11/13/saber-terms-series-woba/comment-page-1/#comment-445 Colin Wyers Sat, 14 Nov 2009 22:15:23 +0000 http://marlinmaniac.com/?p=1166#comment-445 I am going to explain this poorly, but here goes. Park factors are typically expressed in terms of runs per out, and can be used for anything that is in those terms (like ERA, RC27 and so on). Another way of putting it is, a ten percent increase in the measure means a ten percent increase in runs - the linear relationship has a 1:1 slope. That is not true of measures like wOBA, OPS, etc. They all tend to have a relationship closer to 2:1. So you need to adjust the park factor accordingly. Taking the square root is an approximation of the "correct" adjustment. I am going to explain this poorly, but here goes.

Park factors are typically expressed in terms of runs per out, and can be used for anything that is in those terms (like ERA, RC27 and so on). Another way of putting it is, a ten percent increase in the measure means a ten percent increase in runs – the linear relationship has a 1:1 slope.

That is not true of measures like wOBA, OPS, etc. They all tend to have a relationship closer to 2:1. So you need to adjust the park factor accordingly. Taking the square root is an approximation of the “correct” adjustment.

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