A new look at home ice advantage in the WCHA

It started with a good article in the Grand Forks Herald on UND’s home attendance that suggested a link to UND’s (thereby jinxed) home winning streak. A big home ice advantage did mention a home advantage, but only included home winning percentages as supporting evidence. That’s fine, you don’t expect in-depth statistical analysis in a newspaper article that: is trying to make a different point, has a limited word count, and is targeted toward a non-statistical audience.

However, USCHO then ran with the idea of a piece on home advantage, but used home winning percentage to compare “home ice advantage” across teams. Given that, This Week in the WCHA unsurprisingly found that the best teams of the past decade had the largest “advantage” and the worst teams the smallest. They were interesting statistics, but I would argue that they compared teams’ home success, not home advantage.

The problem (for those who missed my Forum post on the topic) is that home winning percentage isn’t really the same thing as home ice advantage. The advantage of home ice is not how well you do at home, but how much BETTER you do at home.

Sticking with winning as the measure for now, here’s how each WCHA team did in WCHA play at home and on the road from the 2001-02 season through the 2008-09 season.

home
win%
road
win%
increased
likelihood
of winning
at home

home

road
wins
losses
ties
wins
losses
ties
CC 74 32 6 52 42 18 0.688 0.545 0.143 26.23%
AA 30 63 19 20 79 13 0.353 0.237 0.116 49.06%
UW 59 40 13 44 50 18 0.585 0.473 0.112 23.58%
Mankato 48 46 18 37 60 15 0.509 0.397 0.112 28.09%
SCSU 56 42 14 47 52 13 0.563 0.478 0.085 17.76%
Mtech 28 64 20 24 76 12 0.339 0.268 0.071 26.67%
UND 62 34 16 60 43 9 0.625 0.576 0.049 8.53%
UMD 45 53 14 38 56 18 0.464 0.420 0.045 10.64%
Denver 65 35 12 61 37 14 0.634 0.607 0.027 4.41%
UMN 62 36 14 62 34 16 0.616 0.625 -0.009 -1.43%

That’s still not quite a perfect measure of home advantage, but as a comparison between performance at home vs. on the road, it’s quite a bit closer.

Anyone who wants to keep the ball rolling by writing a followup critical of this post should start with these caveats:

  • To read this table as measure of home ice advantage would be to pretend that away games are neutral, whereas they instead actually include some home advantage for the opponent
  • It doesn’t correct for strength-of-schedule (e.g. the measure would be distorted if a team scheduled tough opponents at home and cupcakes on the road)
  • It compares only WCHA games
    • This is useful because it actually corrects a little bit for the above two. The WCHA schedule over 8 seasons is somewhat round-robin (though not perfectly so, due to the “rivals” system)
    • However, home advantage could be different when hosting non-conference foes less familiar with a team and its venue
  • I’ve never actually seen anyone try to measure home advantage using win%, it’s usually measured in points scored or scoring differential. So, there may be more problems with this measure that I’m not thinking of right now.

Here’s a quick look, for UND only, at how things would change with different sets of games counted.

home
win%
road
win%
increased
likelihood
of winning
at home

home

road
wins
losses
ties
wins
losses
ties
WCHA games only 62 34 16 60 43 9 0.625 0.576 .049 8.53%
All games (incl. exhibition) 126 54 17 87 57 12 0.683 0.596 .087 14.52%
Exclude tournament games 104 43 17 79 50 12 0.686 0.603 .083 13.79%

This seems to support one of my criticisms above of only including WCHA games — UND’s home advantage is a bit higher hosting non-conference opponents.

One additional point about this table — I was never able to come up with selection criteria that precisely matched the records cited by the USCHO and Herald articles. Focusing on ties, for example, I count 17 total home ties since 2001-02 (18 if you include the tie vs. Minnesota in 2009-10), whereas USCHO and the Herald cite 21 home ties. I compared the schedules at SiouxSports.com, FightingSioux.com, and CollegeHockeyStats.net (see useful summaries at bottom), but couldn’t figure it out. If anyone has any theories or explanations, I’d love to hear them and will cheerfully make any necessary corrections.

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