Simply stated, each team's rating can be thought of as the average rating of
all of their opponents plus their average goal differential in those games.
The reality is a bit more complex as the goal differential considered for any one
game is limited to four, the average opponent rating is a weighted (by games played
against) average, and, since every team's rating is therefore dependent on all of their
opponents' ratings, a recursive algorithm is used which adjusts ratings based on
scores until a minimum difference between expected goal differentials and actual
goal differentials is reached.
The program starts all teams with an equal arbitrary value and then
adjusts them all recursively based on game scores until the lowest cumulative
error between expected goal differentials and actual goal differentials is
reached (convergence). One effect often noticed is that a team's rating can
change slightly without playing due to previous opponents playing which affects
their rating and their opponents rating, etc.
The Rank column simply lists each team's rank, ranks are determined by
by which team has the highest Total. The Total column is actually a
better indicator of where a team stands than the Rank column. For example,
at the time of this writing it can be determined the team that is ranked 5th is actually
as close in Total to 16th than they are to 3rd and therefore would find it easier
to slip down several spots than to move up two spots.
The Total column is in goal units and the difference in this value between
any two teams is the predicted goal differential for a game played at a
neutral site between those two teams. It should be noted that due to goal
differential limits set in the ranking program these predicted goal differentials
are only accurate when comparing teams ranked within two goals of each other.
The differential between teams ranked farther apart becomes more and more
understated as the chosen teams become farther apart in the rankings.
The GmPerf column shows the average goal differential for the team,
calculated using a maximum of +/- 4 for any one game and listed to the nearest
.1 goals.
The Sched column is the weighted (by # games played against) average Total
rating for all of that team's opponents and listed to the nearest .1 goals.
The Total column is the sum of GmPerf and Sched,
listed to the nearest .01 goals.
A teams listed W-L-T record reflects only those games that have been
reported and are in the scores database. Apologies in advance for not being
able to accept scores that are not reported in the proper format.
It should be noted that these rankings are an average performance value
for each team for the entire season, all games are equally weighted, so a team's
latest game may make up only 1/70th of a teams rating at the end of the season.
The Last10 column shows the average performance in the team's last ten games
(for teams that have at least 20 reported scores).
Games that go to shootouts for decision are considered ties for ratings purposes.
