Swept at the GLI — how harmful to PWR?

People who follow the PWR (PairWise Rankings) now know intuitively that getting swept at the GLI was particularly harmful to UND’s PWR (and NCAA tournament) chances, but for the first time ever anywhere, we can try to quantify how harmful.

The surprising bottom line — UND’s chances of getting a top 15 ranking in the PWR are now only about 1/3 to 1/4 what they would have been if UND had instead swept this tournament.

Without further ado, as simulated by the new PairWise Ranking Predictor, here are the distributions of UNDs PWR chances with the actual outcome of the Great Lakes Invitational vs if UND had swept.


Using KRACH to predict the outcomes of unfinished games, UND now stands under a 5% chance of ending the regular season in the top 15 of the PWR.  Had UND swept the GLI, the Sioux would have instead stood over a 20% chance.

A few words about the chart — the horizontal axis is the desired PWR ranking (1 good, 25 bad), the vertical axis is the cumulative probability of achieving the corresponding PWR ranking, the green line represents UND’s actual chances as of today, the blue line what UND’s chances would have been with a sweep.  Note that the KRACH probabilities used to predict the outcomes of remaining games are the same for both — the current KRACH ratings that incorporate being swept.

But wait, Jim, you say… using KRACH to predict the probabilities just extends how teams have performed to date through the end of the season.  The mid-season KRACH last year would have also predicted doom and gloom for the Sioux.  While that’s true, I’m using these predictions to point out how much the differential, how much the sweep hurt, not the actual levels (e.g. 5% chance of finishing top 15).  Nonetheless, another interesting way to look at it is what proportion of the possible remaining outcomes land the Sioux in each PWR ranking.  That can be somewhat answered with a similar simulation that makes the outcomes of each game random (50% win, 50% lose) rather than with probabilities determined by KRACH.


Though a random draw looks better for the Sioux than the KRACH predictions, UND’s chances of a top 15 PWR were harmed even more from comprising 50% of possible remaining scenarios to 15%.  Note further that the number of potential outcomes that even land the Sioux as a TUC fell from nearly 80% to 50%.

A few extra notes for the geeks — the simulations were Monte Carlos with 1,000,000 trials per scenario.  While I didn’t do formal sensitivity analysis, a few runs of one demonstrated that results for each potential ranking were generally within .001%, so I’m pretty happy with 1,000,000 trials.

5 thoughts on “Swept at the GLI — how harmful to PWR?”

  1. Hey Jim,
    Is there a way to back over the last 4 seasons to determine where the Sioux were in the PWR at this point(Jan 1) in the season and where they ended up?

  2. It is somewhat difficult to use the charts to predict the future. Keep in mind that with two games’ actual outcomes decided each weekend, each weekend wipes out 75% of the total remaining possible outcomes. Each time those two games are a sweep, that wipes out 75% of the worst possible outcomes. So, that 1/6 of remaining outcomes that land UND in the top 15 could quickly become 1/2 of remaining outcomes, and so forth.

    What’s the point, then, you say? The point in this post was just to show how severe the impact of the non-conference loss was (something we’ve all suspected but never been able to quantify).

    Going forward, the KRACH-based chart will be a much better predictor, but only when supplemented with unexpected results (e.g. if every game goes as expected EXCEPT UND wins 75% of their remaining games, does that get them in?) This is just a first taste of what this new technology will allow me to do going forward, I’m sure we’ll all dream up all sorts of crazy simulations and ways to interpret the results.

  3. siouxweet-

    I actually did exactly that on Dec 09 here. Check out the table to see PWR/RPI/WIN%/KRACH as of Dec. 9-12 each of the past 4 years.

    Though it’s not explicitly available via drop down menus, you should actually be able to fetch the new data yourself from the ranking trend charts. Just append a season to the request URL, e.g.:

    I haven’t touched those historical charts in about 3 years, so definitely need to update them to make them more accessible and user-friendly. I’ll add it to the list 😉

  4. Tried to post this on the “more on the PWR” but wasn’t able to.

    Not to say that the Sioux don’t need to play with some desperation, but I really don’t know how much trouble they’re in when it comes to the PWR. I just remember how volatile the PWR gets at the end of the season. I remember teams jumping up or down 5, 6,7 spots on the PWR (when it was updated as games came in). Admittedly I have a terrible memory, but, weren’t the Sioux on the bubble in late January, and by the end of the season, they were looming around as a 1 seed? I think they got some help in the F5, and couldn’t help themselves in the end, otherwise would have wound up with a 1 seed?

    I guess what I’m trying to say is that we’ll see the Sioux in the big tournie, even if they don’t get 25 of the still available 32 points. A sweep this weekend could put the Sioux in a tie for 2nd. I know, I’m rambling…I just don’t see the tourny committee snubbing the 2nd, or 3rd place teams in the WCHA, no matter what the PWR says. The 4th place team might be out of luck. With the F4 being in DC this year, and trying to keep costs down, and the $$$ rolling in, there might be 2,3, or 4 teams from the east coast that usually wouldn’t be invited.

    Oh yeah, GO SIOUX!

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