Curious about the effect of certain individual games, I decided to change Maine's 4-2 loss to Mass Amherst to a win and see how it affected the RPI rating (Rating Percentage Index). (note: I have also written a program to calculate the RPI...I only plan to use it for analysis here and there. I added in the rankings of teams in the various factors. Also, I decided to multiply the floats by 100 because I could not get rid of the leading '0' in C++, as in '0.5992', and so my numbers are in a slightly different format from Erik's RPICH although they are actually the same.) Here are the top 5 before and after the change. WITH UMA BEATING MAINE (no change) RPI Opp OppOpp RK G W L T Win% RK Win% RK Win% RK RPI 1 Boston University 25 17- 5- 3 74.00 4 57.45 1 50.26 13 59.79 2 Michigan 23 18- 4- 1 80.43 2 52.92 8 50.04 17 59.08 3 Maine 29 21- 2- 6 82.76 1 49.67 22 51.59 6 58.42 4 Colorado College 28 21- 7- 0 75.00 3 50.15 16 52.17 2 56.87 5 New Hampshire 25 16- 6- 3 70.00 6 52.75 9 49.70 23 56.30 WITH MAINE BEATING UMA (only change Sat Maine-UMA score) RPI Opp OppOpp RK G W L T Win% RK Win% RK Win% RK RPI 1 Boston University 25 17- 5- 3 74.00 4 57.70 1 50.27 14 59.92 2 Maine 29 22- 1- 6 86.21 1 49.67 22 51.73 5 59.32 3 Michigan 23 18- 4- 1 80.43 2 52.92 8 50.03 17 59.08 4 Colorado College 28 21- 7- 0 75.00 3 50.15 16 52.21 2 56.88 5 New Hampshire 25 16- 6- 3 70.00 6 52.66 9 49.66 25 56.25 WHAT HAPPENS Maine effectively lost a spot in the RPI simply by losing the game to UMA, as they fell from 2 to 3 and Michigan moved up. Maine's rating fell from 59.32 to 58.42, a difference of -0.90. Where this is important is in Maine's race with BU for the #1 seed in the East. The loss makes the difference between BU and Maine 1.37 as opposed to 0.60. Since the threshold below which more detailed comparisons can occur (including head to head record) is 1.00 (0.01 in RPICH), a difference of 1.37 means that Maine's +2 head to head advantage (2-0-2) over BU would not come into play if the season ended today. BU would be the top seed in the East. BTW, note that by switching the Maine loss to a win, BU gained in the RPI because of OppWin% (they played Maine 4x and UMA 2x, and Maine would have been a little bit better with a win while UMA would have been a little worse with a loss). On the other hand, UNH lost ground in the RPI with the change because UNH has played UMA 3x and Maine only 2x thus far - but there will still be 2 more regular season meetings between UNH and Maine. It might be interesting after the season is over and all games have been played, to then switch the results of individual games to see how much effect a switch would have had in the end. I am inclined to think that as more games are played, we would see a devaluation in the importance of UMA's win over Maine. The difference of -0.90 in Maine's RPI would likely become smaller, but right now, I don't know by how much. --- --- Mike Machnik [log in to unmask] Cabletron Systems, Inc. *HMM* 11/13/93