Hockey Analytics Glossary
Plain-English definitions for advanced hockey analytics: expected goals (xG), Corsi, Fenwick, Goals Above Replacement (GAR), RAPM, GSAx, Elo, and more. Each entry includes the formula, an FAQ, and the related metrics it connects to.
Advanced
Goals Above Replacement
A comprehensive metric that estimates how many goals a player contributes above what a replacement-level player would provide in the same playing time.
Wins Above Replacement
A metric that converts a player's total goal contribution (GAR) into wins, representing how many additional wins the player adds compared to a replacement-level player.
Regularized Adjusted Plus-Minus
A regression-based metric that isolates a player's individual impact on team goal or expected goal rates by controlling for teammates, opponents, score state, zone starts, and venue using ridge regression.
PDO
The sum of a team's on-ice shooting percentage and on-ice save percentage at 5v5. PDO regresses heavily toward 100 (or 1.000) and is used to identify teams or players benefiting from unsustainable luck.
Replacement Level
The performance baseline representing a freely available player -- typically a waiver claim or AHL call-up. All "above replacement" metrics (GAR, WAR) measure value relative to this baseline.
Elo Rating
A rating system that summarizes each team's strength as a single number, updated after every game based on how the actual result compared to the expected result. Higher Elo means a stronger team.
Expected
Expected Goals
A model-derived probability that a given shot will result in a goal, based on factors like shot distance, angle, type, game situation, and whether the shot is a rebound or rush chance.
Possession
Corsi
A shot attempt metric that counts all shots directed at the net -- shots on goal, missed shots, and blocked shots -- as a proxy for puck possession and territorial control.
Fenwick
A shot attempt metric that counts unblocked shots (shots on goal plus missed shots), excluding blocked shots. Considered slightly more predictive of future outcomes than Corsi.
Situational
Even Strength
Play when both teams have the same number of skaters on the ice, most commonly five versus five (5v5). Even-strength play accounts for roughly 75-80% of NHL game time.
Power Play Percentage
The percentage of power-play opportunities on which a team scores at least one goal. A fundamental measure of man-advantage efficiency.
Penalty Kill Percentage
The percentage of times a team successfully kills a penalty without allowing a goal. The inverse of the opposing team's power play percentage against.
Goaltending
Goals Saved Above Expected
A goaltending metric that measures how many goals a goalie has saved compared to the expected goals total of the shots they faced. Positive GSAx means the goalie saved more than expected.