I used my Even Strength Save Data to look at the effect of Teams. There is not much there.
Using the dense data, I constructed the logits (ln(p/(1-p)) myself. I first corrected the observed save percentages for year.
> LinearModel.2 <- lm(CalcLogit ~ Team, data=Dataset, weights=ESA)
> anova(LinearModel.2)
Analysis of Variance Table
Response: CalcLogit
Df Sum Sq Mean Sq F value Pr(>F)
Team 29 1871.2 64.524 3.8031 1.240e-10 ***
Residuals 895 15184.5 16.966
At a first glance, that looks promising. However, the sum of squares is less than 1/3 the sum of squares we saw for goalies. And we know that teams and individual goalies are highly confounded.
Looking at teams and goalies (with no interaction term)
> LinearModel.4 <- lm(CalcLogit ~ last.first+Team, data=Dataset, weights=ESA)
> anova(LinearModel.4)
Analysis of Variance Table
Response: CalcLogit
Df Sum Sq Mean Sq F value Pr(>F)
last.first 231 6041.3 26.153 1.6677 4.121e-07 ***
Team 29 601.9 20.755 1.3236 0.1209
Residuals 664 10412.6 15.682
Adding in goalies, the significance of the team effect goes away.
Looking at teams and goalies (with interaction)
> LinearModel.4 <- lm(CalcLogit ~ last.first*Team, data=Dataset, weights=ESA)
> anova(LinearModel.3)
Analysis of Variance Table
Response: CalcLogit
Df Sum Sq Mean Sq F value Pr(>F)
last.first 231 6041.3 26.153 1.6835 9.678e-07 ***
Team 29 601.9 20.755 1.3361 0.1156
last.first:Team 168 2707.5 16.116 1.0375 0.3772
Residuals 496 7705.0 15.534
So the effect of goaltenders remains highly significant. The team effect is not significant, and in magnitude is only about 1/10 that of the goaltenders. Finally, we can compare the models directly, to see if adding in team and the team*goalie interaction adds significance to the model.
> anova (LinearModel.1, LinearModel.3, test=”F”)
Analysis of Variance Table
Model 1: CalcLogit ~ last.first
Model 2: CalcLogit ~ last.first * Team
Res.Df RSS Df Sum of Sq F Pr(>F)
1 693 11014
2 496 7705 197 3309.5 1.0814 0.249
And it does not.
Conclusion
Using weighted logistic regression, there is not a statistically significant differences between NHL teams in even strength save percentages over the period 1997-2010 if you control for the effect of individual goaltenders.