How are the ratings calculated?

    Each team's rating can be thought of as that team's average performance throughout 
the year in all games for which a score is listed on this site.  A team's performance in a 
game is defined as the rating of the opponent plus or minus the goal differential in that 
game.   Therefore, the fewer the game scores that go into a teams rating, the less likely 
that team's rating is to truly reflect the season average performance of that team.

    That sounds simple enough,  the only catch is that by this definition all teams' ratings 
are dependent on all their opponents ratings.   The solution is found through the use of 
a recursive algorithm that performs hundreds of iterations until the solution is found for 
which the smallest possible cumulative error is obtained when comparing actual goal 
differentials to predicted goal differentials.

   For 2001-2002, a cap on goal differential considered for the rankings from any HS game has
been set at 4.  This will result in a higher past "predictive" accuracy and a higher weight on
strength of schedule.  Hopefully, playoff predictive accuracy will not be negatively affected.
Experimentation has shown that a cap of a 7 goal spread works better for the college rankings
so that is what is used there.

How accurate are the rankings?

   The past predictive accuracy, the ability of the ratings to explain winners of games that 
have already taken place, is usually in the 80-90% range (excluding ties).  In 2000-01 
for example, the past predictive values for Minnesota and Wisconsin (two of the states 
for which the scores were the most complete) were  84.1% and 89.4% respectively.  The 
future predictive accuracy, the ability of the ratings to predict the outcome of future games, 
is generally about the same to a couple of percentage points lower.

   But perhaps the best indication of how accurate the ratings actually are is not expressed 
in prediction percentages but in the direct comparison between the ratings predictions and 
the coaches' playoff seedings. In all cases (except 1999-2000 in Wisconsin) over the last 
four seasons in comparison with the coaches seedings in Minnesota and Wisconsin these 
ratings (frozen before the start of the playoffs) have beaten the coaches seedings (usually 
by a comfortable margin) in predicting playoff game winners despite the inherent 
disadvantage of having home ice assigned based on the coaches' seedings.

   In 2000-01 the higher ranked team won 61 of 70 games in Wisconsin (4 more than the 
seedings) and 108 of 142 games in Minnesota (two more than the seedings).

What do the numerical values mean?

   The GmPerf value is simply the average goal differential for that team in all games for 
which a score is listed on this site.   

   The Sched value is the weighted (by games played against) average value of all of a 
team's opponents Total values.   

   The Total value is the sum of GmPerf and Sched values.  

   It should be noted that all of these values are in goal units but the Sched and Total 
values only have meaning within each particular ranking (i.e. you cannot compare these 
numbers between two different state rankings or between state and national rankings) and 
only the difference in values between two listed teams is meaningful.  The difference between 
two teams Total values is the difference in average game performance and is in goal units.
Note that when two teams are more than three goals apart in the HS rankings, the spread
becomes somewhat understated due to goal differential caps used in creating the rankings.