New Algorithm Game Predictions – 1/27/2006
It is a very quiet day on the hockey schedule today so I figured it would be a perfect time to unveil version 2 of my prediction and power ranking algorithms which I have spent the last day or two tweaking.
The new algorithms are much more robust and have allowed me to improve my success rates by a couple percent as well as allow me to make predictions on all games. That means no more pick-em games. Here are my (would be) success rates under the old and new systems.
Strong: 94 of 129 – 72.9%
Good: 144 of 222 – 64.9%
Some: 93 of 177 – 52.5%
163 games unpredicted
Strong: 87 of 109 – 79.8%
Good: 129 of 201 – 64.2%
Some: 208 of 372 – 55.9%
Overall I am fairly pleased with the improvements and I am especially pleased that I can now make predictions on all games and get reasonable success rates which are in fact better than the old ‘some’ confidence success rates.
Before I get on to the changes in the power ranking system, here are the predictions for tonights games using the new prediction algorithm.
|Home Team||Road Team||Predicted Winner||Confidence|
I have completely revamped the power ranking system too and because the predictions are based on the same theory used in this power ranking system, I am confident that it is a good indicator how good a team is. Here are the new power rankings as of this morning using this new algorithm.
|Rank||Last Week||Team||AdjWinP||SchedStr||Power Rank|
AdjWinP is a teams winning percentage when shootouts are considered ties and there are no points awarded for overtime losses
SchedStr is an indication of a teams relative difficult of schedule
Power Rank is the teams expected winning percentage if team played all .500 teams
(Note: Last week rank is the rank as of Wed. morning)
The big changes I have made are mentioned in the notes immediately above. Because shootouts are kind of a gimmick and that shootouts aren’t necessarily reflective of how good a team is from top to bottom I have considered shootouts to be a tie game. Also, because overtime losses are reflective of a teams ability to win games (or lose games) I have not considered any points for overtime losses (this is the same as the old algorithm). But the most significant difference is how I account for strength of schedule. I have made significant changes in this regard and because of this significant, and somewhat surprising, results have popped up.
Generally western conference teams have improved their rankings (western conference teams had very good records against eastern conference teams in interconference games) as well as any teams playing in particularly difficult divisions. Teams playing in weak divisions saw their rankings drop. Some of the surprising results are:
Philadelphia being ranked 16th in the NHL and being only slightly above .500 if they had a perfectly average strength of schedule. Montreal is ranked 17th so I guess Montreal beating the Flyers the other day might not have been that much of an upset.
Nashville has also dropped dramatically, partly due to their weak schedule but partly because of the number of shootouts and overtime losses they have played in (same for Philly for that matter).
The NY Rangers are another team that has benefitted dramatically from an easy schedule and ovetime loss points and shootouts as they are ranked 21st in the NHL under my power ranking system. Division rivals Islanders and New Jersey also drop significantly in the rankings.
Calgary, Vancouver, Colorado, Edmonton and Minnesota make up the toughest division in the NHL and as a result all saw their rankings improve dramatically and all are ranked in the top 13 in the NHL.
Some of these results may be quite surprising but I do have confidence in them. I do because my prediction algorithm seems relatively good at predicting games. An example is Montreal defeating Philadelphis mentioned above. Other examples are Minnesota defeating Nashville last night. Just looking at the standings you wouldn’t think Montreal or Minnesota would have a chance but if you look at the power ranks above you’ll see they aren’t that far apart. Upsets will always happen (like Chicago defeating Calgary last night) but some upset aren’t as big of upsets as one might initially think.