Technical Info on PageStat
This FAQ (Frequently Asked Questions) pertains to the version I use to rank Minnesota Boys' High School Hockey teams. It is the result of questions which have been asked about PageStat during the past several years. Hopefully, if you have questions about how the system works and the results, you'll find the answers there and save the necessity for you to email me about your questions and concerns.
Before emailing me with questions about the ratings, read this information first! Questions which are covered here won't be responded to in email.
Q: How often are the ratings updated?
A: Current ratings are generally updated each Monday.
Q: A team hasn't done very well early in the season. How could they be rated so high?
A: PageStat not only looks at how each team has done this season, but also looks at their results from the previous season. As a team plays more games, last season's results are gradually phased out. This is done because you can't, in many cases, derive much from how a team does in their first few games. Eventually, teams' results from last season are completely phased out.
Q: We have a better W/L record than another team in our conference, section or division. Why are we rated lower?
A: A team's W/L record is meaningful only when also taken into account along with the strength of the teams they have played. If you play weak teams, and don't do as well against those teams as other teams do, your rating won't be as high.
Q: But we beat a team handily which is rated above us. What gives?
A: The obvious answer to this is that one game does not a season make. You can't rate one team ahead of another team simply because they beat them in head-to-head competition. There are 25 regular season games, and up to seven more in section and State tournament games. No single game is given more weight than any other game played.
Also, by using the "our team beat your team" argument, it can lead to a "circular logic" of sorts. Team A beats Team B which beats Team C which beats Team A. See how that works?
Q: We should be rated higher, but we've had a player or players injured. Isn't that taken into account?
A: No. How could this possibly be programmed into a system? Different players have a different impact on a team's results. Assigning a value to a player who is injured is nearly impossible. It could be done, but it would be a logistical nightmare. I'd have to know, at any given time, every player who was injured in Minnesota, and what their stats were prior to being injured.
Q: Lately our team has been doing very well. We just started slowly. Isn't that taken into account?
A: It is taken into account. The system give a heavier weight to recent games played than to games played earlier in the season.
There have been a number of issues raised by people which have led to changes in how PageStat works. Appreciation is expressed to those whom have raised such issues!
PageStat has its roots in the 70's, when it was developed as a means of rating NFL teams. There were never any real objective studies to see how well it worked; my memory was that it had some success in predicting winner of upcoming games. You wouldn't get rich in Las Vegas using it, however.
I imported it in 1997 to Minnesota high school hockey. It was in reponse to a basic question I had of how all teams in Minnesota stacked up against each other. Tom Hawley's ratings, which used to be posted weekly in the Duluth News-Tribune, really piqued my interest. And so the project was started.
The system has undergone a number of revisions, and two huge overhauls. By overhaul I mean that the system was torn completely down and redone from scratch. The basic information which goes into these ratings from hasn't changed, however; results of games, and strength of schedule.
PageStat was eventually expanded to also cover NFL football and NCAA D-1 Mens' Hockey. At some point it will also be extended to NHL hockey.
After a lot of experimentation, I've come to an obvious conclusion; it's impossible to develop a system that's perfect or is even 100% objective. After all, the weight given to each data piece is really determined by the person creating the system. What I believe to be important may be considered more or less so by someone else using the same data.
The goal has always been to come up with some kind of ranking system for teams that looks reasonable. In reality, however, even that is open to all kinds of debate. Accuracy is in the eye of the beholder. I recognize this along with the implication that some will think this system isn't worth the web page it's posted to. Some will like it. Hey, I crunch numbers for a living and this project has been a fun one to work on. It it wasn't fun, or was a lot of work, I wouldn't do it.
Nuts and Bolts
The following things are taken into account when determining a team's PageStat ratings:
The goal differential in each of their games
The PageStat rating of each opponent a team has faced.
When the game was played. Remember, from before, games played more recently carry more weight (Note that the "momentum factor" is not curently applied to NFL football).
The following things are not taken into account:
Injuries a team has suffered. This would be nearly impossible to program into the system, so it is ignored.
Tradition. How can you put a numerical value on the fact that a team is the defending state champion in either class? Even if you could, what value would you place on that?
How the pollsters and other so-called experts would rate a team. Humans are subject to bias and are limited to only the games they've seen. Unless you are able to see every game which every team in Minnesota has played, your expertise is limited. Even if it were humanly possible to see every game, you still have bias. Count on it.
How good a team is "supposed" to be this season. PageStat doesn't account for how many players you have returning, how you are expected to compete for your Conference or Section title. The results on-ice are all that matters, not how things are supposed to be.
Each team starts the season with a pre-determined number. An average is assigned to teams who didn't have a previous PageStat rating, and for other teams, their previous PageStat rating is used. Then the process begins of assigning a "point value" to each game every team has played, using their rating, their opponent's rating, and the goal differential. There is a "cap" beyond which a larger differential no longer brings a higher game rating. Games between teams with a PageStat rating difference higher than this cap are ignored. This is done to prevent a team's rating being lowered because they beat up on a very weak opponent.
Once this is completed, the ratings are run until they have been run enough times to no longer significantly affect any team's rating.
last updated december 9, 2016