They're here for 2018: Boys and girls hockey RPI and ratings


 

The calendar has flipped pages to 2018, the Patriots are getting ready for another run to a Super Bowl, and the weather finally has turned cold and snowy. (Or is it balmy and monsoon-like? … No, wait, it’s going to be chilly and icy again. Anyway …)

We’ve reached January, and it’s hard to believe we’re already a full month into the high school hockey season. That means we’ve got enough data at our disposal in the official In the Slot supercomputer to roll out the Herald’s version of the Ratings Percentage Index (RPI) and various other computer ratings for 2017-18.

As a refresher, we remind everyone that these ratings are “for entertainment purposes only” and that we have no affiliation with the MIAA, the Mass. State Hockey Coaches Association or any other group. But in the past decade that we have been doing this, officials and Super Eight voters have, to varying degrees, put some stock in our numbers as a way to “take the temperature” of the high school hockey landscape in an unbiased, analytical way.

The ratings on the spreadsheets posted below work as follows:

RPI: The actual Ratings Percentage Index used by the NCAA to help select and seed tournaments in most team sports. The basic formula is a.) 25 percent  of a team’s winning percentage; + (b.) 24 percent of a team’s opponents’ combined winning percentage; + c.) 51 percent of those opponents’ opponents’ combined winning percentage. (Some adjustments are made in the overall math.)

WALKER: The system used by Western Mass. in all team sports, and now for some sports in Central Mass., to “power seed” the tournament brackets. Its formula consists of a.) winning percentage; + b.) strength of schedule; + c.) record against tournament-qualified opponents. Should the MIAA ever decide to go ahead with power seeding in Eastern Mass., this is a system that could be used. (We also produce a “statewide” Walker rating, but we remain skeptical at this point how well it works with such a large and varied pool of teams.)

KRACH and KRAtio: KRACH is a formula popular in college hockey that ranks each team on an odds scale (i.e. Team A rated 750 would be considered three times more likely to win a game against a Team B rated 250). … Whereas KRACH only considers whether a game is a win, loss or tie, “KRAtio” uses the same formula but inputs the actual game score to give each team a percentage of a win and loss for every game played.

SCORE and WIN: SCORE is based…



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