This document is intended to answer frequently asked questions about GUPA's Leaguerunner implementation.
Please note that this document is a work in progress. As such, if there are questions you'd like answered, please don't hesitate to contact the webmasters
The SBF is the "Spence Balance Factor". It was suggested during discussions about Thursday Indoor 2003 as a way to see how balanced a particular tier was.
The Leaguerunner implementation of the SBF is a straight average of the point differentials (as a positive number) of all games played. In the case of the League SBF, this is all games in the league. For the Team SBF, this is all games played by that team.
Assuming that this measurement has actual statistical validity (something that has not yet been proven), these numbers can be used to measure the 'closeness' of game scores for a tier/division or a team. Tiers with lower SBF values generally have closer games, and thus are more balanced. Teams whose SBF is much higher than the SBF for the tier they're in may be good candidates for moving up or down (depending on their win record) to another tier.
The rating, as shown on the team view page and on the standings, is a measure of the team's past performance. Higher ratings indicate that a team has done well against its previous opponents and should probably do well against opponents with lower ratings in the future.
The rating system used by Leaguerunner is based on the Elo system which was originally designed for ranking chess players. The system was adapted for team sports in 1997 by The World Football Elo Ratings site, and further modified to be more applicable for Ultimate by the author of Leaguerunner.
Here's how it works. Each team starts at 1500, and moves up or down from there based on game performance. Each game is worth a base value, adjusted for strength of schedule (based on your rating as compared to your opponent's rating) with bonuses given for higher point-differentials (games won by a difference of more than 1/3 the winning score). The winning team gets the value for that game added to their rating, and the losing team gets it subtracted. In this manner, "upset" wins are worth more than "expected" wins for rating purposes, so if a team with a 1500 rating beats one with a 1600 rating, it's a higher-value game than if the 1600-rated team beat the 1500-rated one.
Further details, as well as the mathematical formulas used to calculate the rating, will be posted here later.