THE BOOK--Playing The Percentages In Baseball

Monday, September 20, 2010

Fans Scouting Report: Another Update

Yes, I’d still like more Marlins fans.  For the fans of other teams, feel free to do the “new” players, like Cody Ross with the Gigantes.

Anyway, this is a small note to say I made a small adjustment to the calculations.  As a way to regress toward the mean, I added two ballots of all average ratings to every player.  Basically, you are not going to notice the difference to anyone, other than guys with just a handful of ballots.  A good example is Brett Carroll of the Marlins.  He had a high rating (81 or something) before the adjustment, but that was based on 6 ballots.  If I add in 2 ballots of all 50s, then that becomes 73.

IMDB also does that for their top 250 movies of all time:

weighted rating (WR) = (v ÷ (v+m)) × R + (m ÷ (v+m)) × C

What they do is add 3000 votes of average rating (6.9).  With top movies getting 500,000 votes, obviously this is not going to matter.  You have Toy Story 3 with only 68,000 votes at a rating of 8.9.  After doing the regression (adding 3000 votes at 6.9), the new weighted score is 8.8.  (Due to rounding, they are showing it as 8.7).

http://www.tangotiger.net/scout/