BPF calculation

[yankees-chick]

Hello I'm looking for the full explanation/equation for how bill james and the like calculate their ballpark index...

if someone knows, that would be great

[digglahhh]

http://www.baseball-reference.com/about/parkadjust.shtml

This is the formula given on baseball reference.

Just a couple of warnings though. First players who hit in great parks lose out on park adjustments b/c they don't get the to play road games in their home park, so a guy who plays at Coors doesn't get Coors games counted in his road comparison.

Second, the park factor is rather general and parks effect different types of hitters differently. The park factor is only a thumbnail sketch if you don't actually know the nuances of the park and the type of hitter the guy you are looking at was.

Third good hitters make good parks. Jacobs Field is not particularly good for hitters, but the PF was over 100 for most of the late 90s because the team was such a potent offensive force. In other words the conclusion and those for which the conculsion attempts to conclude overlap. Every park is a great hitters park when you are Manny Ramirez...