Personal Goals Against Average

Personal Goals Against Average is an NHL statistic invented by Alan Ryder of hockeyanalytics.com, designed to estimate a player's defensive ability. It is similar to hockey's existing Plus/Minus system, except that it only deals with the "minuses", leaving out plusses because it focuses only on defense. The idea is to find a statistic similar to goaltenders' Goals Against Average that applies to skaters, with the implication being that players whose teams give up fewer goals while they are on the ice must be better defenders than players whose teams give up more goals. The formula is simply:

uPGAA = (60 x Minuses) / Minutes on Ice

This is the raw (unadjusted) PGAA, which is reasonably effective for evaluating defenders across the league, and works especially well when comparing players on the same team. However, the raw numbers can be distorted by the defensive quality of each player's teammates, so a final adjustment must be made to account for this:

aPGAA = (uPGAA / (Team Minuses/Min)) * (League Minuses/Min)

The resulting figure can be more readily compared across teams.