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08-23-2011, 07:02 PM
  #190
plusandminus
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Quote:
Originally Posted by overpass View Post
Glossary of Terms:

SFrac: Season Fraction. 1.00 is a full season. I prefer it to games played because it gives a 48 game season, a 74 game season, an 80 game season or an 82 game season the same weight.
$ESGF: Even-strength goals for, normalized to a 200 ESG scoring environment and with estimated SH goals removed.
$ESGA: Even-strength goals against, normalized to a 200 ESG scoring environment and with estimated SH goals removed.
R-ON: Even strength GF/GA ratio when the player is on the ice.
R-OFF: Even-strength GF/GA ratio when the player is off the ice.
XEV+/-: Expected even-strength plus-minus, which is an estimate of the plus-minus that an average player would post with the same teammates. The calculation is described above.
EV+/-: Even –strength plus-minus, which is simply plus-minus with estimated shorthanded goals removed and normalized to a 200 ESG environment.
AdjEV+/-: Adjusted even-strength plus-minus, which is even-strength plus-minus minus expected even-strength plus-minus. This is the final number.
The following three stats evaluate special teams play and are not related to adjusted plus-minus. I’m including them in the table for a quick reference to the player’s contributions outside of even-strength play.
PP% : The % of the team’s power play goals for that the player was on the ice for.
SH%: The % of the team’s power play goals against that the player was on the ice for.
$PPP/G: Power play points per game, normalized to a 70 PPG environment and with pre-1988 PP assists estimated.

Results
Here are the top 60 in career adjusted even-strength plus-minus, as well as the players in the HOH Top 100 and several others who were strongly considered for voting.

Rk Player SFrac $ESGF/G $ESGA/G R-ON R-OFF XEV+/- EV+/- AdjEV+/- /Season PP% $PPP/G SH%
1 Ray Bourque 20.30 1.17 0.85 1.37 0.96 -62 524 586 29 88% 0.45 58%
Sorry, but I'm still a bit confused.
The text says $ESGF and $ESGA are adjusted to 200 ESG scoring environment.
The $ prefix makes me think "adjusted to 200 ESG scoring environment".
The text says EV+/- is also adjusted to 200 ESG scoring environment. ?

If it had been named "$EV+/-", I would have been pretty sure it's $ESGF-$ESGA, because $ tells me that it's "adjusted to 200 ESG scoring environment".
My question is... Is EV+/- = $ESGF-$ESGA ?

The text also says:
Quote:
To calculate the adjusted plus-minus, I take the player’s on-ice total goals for and against as given. I calculate an expected plus-minus for the player, based on his team’s off-ice performance.
"As given", does that mean they are not "adjusted to 200 ESG scoring environment"?


Example, using made up seasonal stats for one player and his team.

Everything is ES only.
"without" or "w" means when player was off the ice.
GD (goal difference) = GF-GA.

Lge aver ESGF per team teamGD teamGF teamGA playerGD playerGF playerGA withoutGD withoutGF withoutGA pGF/pGA wGF/wGA  
100 +20 60 40 +10 24 14 +10 36 26 1.714 1.385 

Lge aver ESGF per team $teamGD $teamGF $teamGA $playerGD $playerGF $playerGA $withoutGD $withoutGF $withoutGA pGF/pGA wGF/wGA  
200 +40 120 80 +20 48 28 +20 72 52 1.714 1.385 

Are the $ values above true? Is that how the ""adjusted to 200 ESG scoring environment" values are calculated?

If the above is correct, then how do we use the different variables to calculate the missing columns?
R-On? R-Off?


Can someone write down the formula's for calculating the values, using the variables of the tables above?

And can we write "rOn" and "rOff" instead of "R-On" and "R-Off", to make it easier to understand the formulas? ("-" can otherwise be interpreted as a minus sign. But we don't take R minus On, and R minus Off, right? If, I'm even more confused.)





Quote:
The expected plus-minus is calculated using the off-ice performance regressed partially to even, as a player should be expected to play somewhat better than a set of bad teammates or worse than a set of good teammates.
I understand the regression thing. But I'm confused about other things, including what exactly to regress (I guess it's "wGF/wGA"). ? Is rOff = "wGF/wGA" regressed to even?

Quote:
I then calculate an actual plus-minus, which differs from official NHL plus-minus in that it is normalized to a scoring environment of 200 even-strength goal per season and does not include shorthanded goals. I subtract the “expected plus-minus” from the “actual plus-minus” to generate an adjusted plus-minus number.
I think I need an example to understand.

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