Power Ratings are a computerized ranking system based on a team's performance against other teams in the league.

The IHSLA does not use power ratings to determine conference champions, state champions, or playoff seeding positions. They are provided purely for informational purposes for the coaches, players and fans.

There are dozens, perhaps hundreds, of power rating schemes employed in sports. The power rating method utilized on this site is similar to the "Margin of Victory" method used by LaxPower.com. However, it only considers play within the IHSLA and ignores games played outside of Illinois. The IHSLA method employs two "adjustments" to the standard power rating scheme.

The "10-Goal Limit" factor (TGL)

The TGL adjusts the ratings in such a way that a winning team will not gain additional power points if they win by more than ten goals. Similarly, the defeated team will not lose power points if they lose by more than ten goals. The IHSLA recognizes that a ten-goal differential in a game results in many unusual situations such as a running clock, more substitutions, etc. that may not represent the true performance of either team. In addition, the TGL removes any incentive for a coach to "run up the score" merely to improve the team's power rating.

The "Top Team" factor

The scores from various games are not all weighted equally. Games in which the opponent is highly rated are weighted more heavily than games in which the opponent is rated lower. This factor provides more power points to the teams with difficult schedules and reduces the power points for teams with easier schedules. It rewards teams who win against strong opponents, and it diminishes the rewards for teams who win against weaker opponents.

Strength of Schedule (SOS)

The SOS rating (not displayed) is a reference to the strength of a team's opponents. It is calculated from the average power rating for a team's opponents in games played. The SOS rating does not reflect the strength of opponents for unplayed games, exhibition games, or tournament games. The SOS Ranking (displayed) is a team's rank relative to the other teams based on its SOS rating. The higher the SOS rating, the lower the SOS rank. The SOS ratings and rankings are not used directly in any other calculations because the power ratings are already weighted in favor of strong opponents using the Top Team factor.

But what does it all mean?

The power rating system is a computerized method of predicting the difference in scores between two teams. Theoretically, a team with a power rating of 95 is expected to defeat a team with a power rating of 92 by three goals on a neutral field. Of course, the actual outcome of such a game may be different depending on many circumstances, but, on average, the power ratings tend to properly rank teams based on how they performed against one another. The more games that are played within the league, the more accurate the power ratings reflect the true performance of the teams and the stronger the prediction mechanism becomes.

How accurate is it?

A study was conducted on the IHSLA data (May 19, 2009) after about two thirds of the season's games were played. The study compared the actual game results to the predicted goal difference between the two teams based on the power ratings. The statistical analysis suggested the power rating prediction has a standard deviation of about +/- 3 goals. To put it another way, roughly 70% of the games played had actual results within 3 goals of the predicted goal difference.