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10-10-2012, 02:36 PM
Czech Your Math
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Originally Posted by Hockey Outsider View Post
I've had this idea for several years (I don't remember if I've ever written about it here). This would be the most objective and rigorous way of quantifying the importance of players' offensive contributions.

The problem is that, in addition to the score, there are two other essential variables: the time remaining in the game, and league scoring context.

For example, a goal that gives a team a 1-0 lead at 1:00 of the first period might be worth 0.15 (hypothethically increasing the win probability from 50% to 65%). However, a goal that gives a team a 1-0 lead at 19:00 of the third period might be worth 0.45 (hypothethically increasing the win probability from 50% to 95%). This method would require a rigorous analysis of the win probability added based on the score in the game and the time remaining.

A more subtle (but equally important) consideration is the scoring context. A 2-1 goal at 15:00 of the second period might would be worth a lot more in, say, 2002, compared to 1982, given that the former season had far fewer goals per game, thus making each goal more important to a team's chance of winning. (Another way of thinking about it: given that there was so little offense in 2002, it's far more likely for a team to hang on to a 2-1 lead with 5 minutes left in the second period, compared to the wide-open 1982).

I spent some time working on this perhaps 7-8 years ago but gave up quickly after realizing how much work was required (also, the relevant data was much harder to find than it likely is today).
I agree that this would be the best approach in assigning importance to players' goals/points. If the data is readily available in proper format, it seems very possible. I would guess there exists the proper formula to calculate win% based on score and time remaining, given the avg. scoring rate for the league. IIRC there was at least one link to a logarithmic formula in the "do teams pull their goalie soon enough?" thread and/or the "ideas for future studies" sticky thread (both in this forum), although I didn't delve into those links, so I am not certain of their applicability to this question.

One complication since the lockout is the shootout, and there was an extra point for OT games for a while even before the SO existed. This would seem to give greater importance to a tying goal than a goal which puts a team in the lead, an unfortunate side effect of a poorly designed team point structure by the NHL.

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