THE BOOK--Playing The Percentages In Baseball

Monday, February 08, 2010

Publication bias

This appeared on Baseball Prospectus:

For 2003: Jan, 2004:

But for the time being at least, it looks like PECOTA walks the walk.

For 2006: Dec 2006:

Although we’d like to confirm these results independently, Chone Smith, a poster at Baseball Think Factory, has run a comparison of projection systems in 2006 and PECOTA has come out on top, with a huge lead in position player projections and a very narrow second place in pitcher projections.

For 2007 and here: Oct 2007:

{hitters} So, another good year from PECOTA, certainly a good year from ZiPS — Dan does excellent work. I think we can call those two co-champs, but several of the other systems weren’t far behind.
...
{pitchers} The best you could have done last year is to bundle PECOTA and CHONE in about a 4:3 ratio.

***

This did not appear at Baseball Prospectus:

For 2007-08, and written by CURRENT BPro author Matt Swartz in Apr 2009:

--CHONE was the best at projecting most things.
--PECOTA was very close behind but had some systematic biases, specifically for speedy players’ BABIPs, which ZIPS struggled with as well.

Can the Bpro editors approach and pledge to not fire Matt Swartz if he repeats his study for the 2009 season?