Goaltending Statistics - Glossary of Terms

I use some non-standard terminology on this site (and some standard terminology). This page attempts to catalogue the various metrics presented here.

AGE

 For each season, I define the age of the player as their age as of January 1 of that season. This is roughly the midpoint of most regular seasons, and has a certain calculation advantage.

GP

 This is the number of games played by the goaltender during the season. I only count games where a goaltender appears in net (and not games on the bench as the dressed backup). Many European leagues differentiate between games dressed and games played in; on this site, GP reflects the latter.

MIN

 This is the number of minutes played by the goaltender during the season. Where available, I keep this information at the minutes/seconds level in my database, and report only the (rounded) minutes here.

W, L, T, OTL

 These are the number of wins, losses, ties, and overtime/shootout losses recorded by the goaltender during the season.

For every league that I can think of, the current definition of these are the goaltenders in net at the time of the game-winning goal (the N+1th goal, when the losing team scores N goals).

At some levels of leagues, the published statistics do not allow easily to see whether a goaltender won or lost in overtime - recent KHL statistics have this feature. Here, I've included both into the "T" column.

Some leagues separate OTL and SOL - I combine these here. If I have separate shootout statistics, I keep them separately (in another column).

WPCT

 This is the winning percentage of the goaltender during the season, although it's better expressed as points percentage:

(2*W + T + OTL) / (W + L + T + OTL)

Note that for seasons with "loser points", this will result in the "average" goaltender having a points percentage of greater than 50%.

GA

 The number of goals allowed by the goaltender during the season.

GAA

 The goals-against average for the goaltender during the season:

GAA = (GA)*(60)/(MIN)

The intent of the goals-against average is to put seasons of different length on an even footing, reporting the number of goals the goaltender gives up (on average) in a sixty-minute game.

SA

 The number of shots faced by the goaltender during the season. Only "shots on goal" are counted here - shots that would have gone into the net had the goaltender not stopped them (posts do not count as shots, for instance).

Pre-1982 NHL shot (and save percentage) information comes from a second-hand Excel workbook done by Roger Brewer, using data from the Hockey Summary Project (a tremendous endeavor by both). It is not considered official National Hockey League dogma.

SVPCT

 The fraction of shots faced by the goaltender that were prevented from becoming goals, expressed as a decimal.

SVPCT = (SA - GA)/(SA)

S/60

 The number of shots the goaltender faced in an average sixty-minute game during the season.

S/60 = (SA)*(60)/(Min)

ShO

 The number of shutouts accumulated by the goaltender during the season. To record a shutout, a goaltender has to be the only goaltender on the ice for a team allowing zero goals (there are also "team shutouts" where two goaltenders share a shutout).

G, A, PiM

 The number of goals, assists, and penalty minutes accumulated by the goaltender during the season. These are traditionally "skater statistics", but can be interesting or revealing for goaltenders.

UNI#

 The sweater (uniform) number(s) worn by the goaltender during the season. I'm working to get more of these into the database.

SOUT

 The goaltender's performance in tiebreaking shootouts during the season. Four numbers are presented here: shootouts won, shootouts lost, shootout saves made, and shootout shots faced.

Note that I vary the definition of a "save" here to include any attempt that does not result in a goal (including shots that go wide). If you prefer, think of this as shootout goals prevented.

Z-SCORE

 This is the first of several save percentage translations on the site. Many times, differences in save percentage between goaltenders can be the result of random fluctuation. This statistic asks the question "if this goaltender were truly a league average goaltender, facing the number of shots that they faced, how remarkable would their actual performance have been?".

For instance, suppose that a league-average goaltender had a save percentage of 90%, and faced 100 shots on goal. The truly league average goaltender would allow 10 goals on these 100 shots. Suppose that our goaltender instead allowed 8 goals. Assuming a binomial distribution (I note that this may not be fair), we can calculate how many standard deviations above (or below) average this goaltender's performance was:

ZSCORE = ((Saves) - (Shots * League Average SV%)) / SQRT (Shots * League Average SV% * (1 - League Average SV%))

Or, in this case:

ZSCORE = (92 - 90) / SQRT (100 * 0.9 * 0.1) = 0.67, indicating that the goaltender was above average but not in a statistically significant fashion.

Truly remarkable performances (good and bad) start at about 2 standard deviations away from average, and the larger the number, the more significant.

(In the calculation of league-average save percentage, I remove the goaltender in question from the totals.)

GD

 This statistic, Goal Differential, measures how many goals the goaltender prevented above a league-average goaltender. I would have preferred "goals above average" here, but the abbrevation presents its own problems.

A league-average goaltender would allow (1 - League Average SV%) * (Shots Faced) goals, and so:

GD = ((1 - League Average SV%) * (Shots Faced)) - (Goals Against)

GAR

 This statistic measures how many goals the goaltender prevented above a replacement-level goaltender. One problem with the statistic above (Goal Differential), is that it suggests the notion that an "average" goaltender has no value. To the contrary, playing at the league average generally earns NHL goaltenders millions of dollars each year.

This statistics, Goals Above Replacement, attempts to quantify that value by comparing how many goals a goaltender prevented above a replacement-level goaltender. On this site, "replacement level" represents the best goaltender that a team could find on short notice with small resource expenditure (either the top goaltender on their minor league team, or the top free agent available). I need to analyze this more rigorously at some point, but here, replacement level is defined as 1.5% below league average (so if the league average goaltender is at 90%, then replacement level is defined as 88.5%). And thus:

GAR = ((1 - (League Average SV% - 0.015)) * (Shots Faced)) - (Goals Against)

SNW%

 This statistic, Support-Neutral Winning Percentage, asks the following question - if a goaltender played for a team that allowed as many shots against as shots for, and was playing against a league average goaltender, what would their winning percentage be? On this site, the calculation is done using the "basic" Pythagorean formula to predict winning percentage

SNW% = (Goals Scored^2) / ((Goals Scored^2) + (Goals Allowed^2))

Or in this case:

SNW% = ((1 - League Average SV%) * Shots Allowed)^2 / (Goals Against^2 + ((1 - League Average SV%) * Shots Allowed)^2)

Note that, unlike the goaltender's winning percentage, this metric is guaranteed to be such where a league average goaltender scores out with a 50% winning percentage.

SNW, SNL

 Support-Neutral Wins (and Support-Neutral Losses) take a goaltender's support-neutral winning percentage (calculated above) and partitions their actual number of decisions by that percentage.

For instance, suppose that a goaltender had an (actual) record of 7-3-0, with a support-neutral winning percentage of 60%. They had ten decisions, and so their support-neutral wins would be 6 (and support-neutral losses would be 4).

On some level, this suggests that things not measurable by save percentage (either team offense, or team defense, or biases in save percentage) gave the goaltender an "extra" win.

Lastly, I should note here that, while save percentages are considered a decent statistic for evaluation of a goaltender's individual performance (certainly better than goals-against average or wins and losses), it is by no means a perfect statistic. I will write more to this at a later date, but for now, please keep that in mind.

To The Goaltender Home Page