I don't know if this belongs here or not, if it doesn't I apologize ahead of time and please move it to the appropriate place.
From ESPN: Park factor:
Park Factor compares the rate of stats at home vs. the rate of stats on the road.
A rate higher than 1.000 favors the hitter. Below 1.000 favors the pitcher.
PF = ((homeRS + homeRA)/(homeG)) / ((roadRS + roadRA)/(roadG))
* Teams with home games in multiple stadiums list aggregate Park Factors.
Here's the link. It also shows all of the different park factors around baseball.
http://sports.espn.go.com/mlb/stats/parkfactor