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.
PDO (named after an anonymous hockey blogger's screen name) is the simplest and most powerful luck indicator in hockey analytics. It is calculated by adding a team's or player's on-ice shooting percentage (goals scored / shots on goal) to their on-ice save percentage (1 - goals allowed / shots on goal against). The result centers around 100 (or 1.000 when expressed as a decimal).
The key insight behind PDO is that both shooting percentage and save percentage regress heavily toward league averages over time. A team with a PDO of 103 is likely benefiting from a combination of hot shooting and strong goaltending that will not fully sustain. Conversely, a team with a PDO of 97 is probably due for positive regression. PDO is sometimes called the "luck metric" because it captures the variance in outcomes that is not explained by shot quantity or quality.
PDO is most useful as a flag for unsustainable performance. If a team is winning despite poor possession numbers, a high PDO explains why -- and suggests regression is coming. If a team is losing despite dominating possession, a low PDO suggests better results are ahead. It is not a perfect luck measure (some elite goalies and shooters can sustain above-average rates), but it is an excellent starting point.
Formula
PDO = On-Ice Shooting% + On-Ice Save% Shooting% = Goals For / Shots on Goal For Save% = 1 - (Goals Against / Shots on Goal Against) League average PDO = 100 (or 1.000)
Frequently Asked Questions
What does PDO stand for?
PDO does not actually stand for anything. It was the screen name of a blogger on the HFBoards hockey forum who popularized the concept. The name stuck and has become standard hockey analytics terminology.
What is a "normal" PDO?
League-average PDO is 100.0 (or 1.000). Most teams finish the season between 98 and 102. Anything above 102 or below 98 is a strong signal of unsustainable performance. At the individual player level, PDO can vary more due to smaller sample sizes.
Can a team sustain a high PDO?
To a limited extent. Teams with elite goalies or unusually talented shooters can sustain PDO slightly above 100. However, extreme PDO values (above 103 or below 97) almost always regress significantly. Very few teams in NHL history have sustained a PDO above 102 for a full season.
How should I use PDO in analysis?
Use PDO as a sanity check. If a team or player has great results but poor underlying numbers (Corsi, xG), check their PDO -- it likely explains the discrepancy and suggests regression. PDO is also useful for identifying buy-low/sell-high opportunities in fantasy hockey and trade analysis.