Super 15 Prediction for the Final
Team Ratings for the Final
The basic method is described on my Department home page.
Here are the team ratings prior to this week’s games, along with the ratings at the start of the season.
| Current Rating | Rating at Season Start | Difference | |
|---|---|---|---|
| Crusaders | 10.77 | 10.42 | 0.40 |
| Hurricanes | 9.06 | 2.89 | 6.20 |
| Highlanders | 6.98 | -2.54 | 9.50 |
| Waratahs | 6.13 | 10.00 | -3.90 |
| Brumbies | 4.27 | 2.20 | 2.10 |
| Chiefs | 3.58 | 2.23 | 1.40 |
| Stormers | 0.47 | 1.68 | -1.20 |
| Bulls | 0.39 | 2.88 | -2.50 |
| Lions | -0.55 | -3.39 | 2.80 |
| Sharks | -0.65 | 3.91 | -4.60 |
| Blues | -4.49 | 1.44 | -5.90 |
| Rebels | -4.89 | -9.53 | 4.60 |
| Force | -7.16 | -4.67 | -2.50 |
| Cheetahs | -8.22 | -5.55 | -2.70 |
| Reds | -8.70 | -4.98 | -3.70 |
Performance So Far
So far there have been 124 matches played, 81 of which were correctly predicted, a success rate of 65.3%.
Here are the predictions for last week’s games.
| Game | Date | Score | Prediction | Correct | |
|---|---|---|---|---|---|
| 1 | Hurricanes vs. Brumbies | Jun 27 | 29 – 9 | 7.80 | TRUE |
| 2 | Waratahs vs. Highlanders | Jun 27 | 17 – 35 | 6.40 | FALSE |
Prediction for the Final
Here is the prediction for the final. The prediction is my estimated expected points difference with a positive margin being a win to the home team, and a negative margin a win to the away team.
| Game | Date | Winner | Prediction | |
|---|---|---|---|---|
| 1 | Hurricanes vs. Highlanders | Jul 04 | Hurricanes | 6.10 |
David Scott obtained a BA and PhD from the Australian National University and then commenced his university teaching career at La Trobe University in 1972. He has taught at La Trobe University, the University of Sheffield, Bond University and Colorado State University, joining the University of Auckland, based at Tamaki Campus, in mid-1995. He has been Head of Department at La Trobe University, Acting Dean and Associate Dean (Academic) at Bond University, and Associate Director of the Centre for Quality Management and Data Analysis at Bond University with responsibility for Short Courses. He was Head of the Department of Statistics in 2000, and is a past President of the New Zealand Statistical Assocation. See all posts by David Scott »
Dear Dave, I struggle to understand the logic of your prediction system. The Crusader remains the highest ranking even after ending 6th on the log. I would expect that there should be a high correlation between final log point (excluding bonus points) and rating points or points difference and rating points. I also noticed that the total rating point decreased from 12.77 to 11.93. How was this points lost. . How are older results diminished in the ratings or do all results have the same value irrespective when the game was played.
9 years ago
The Crusaders anomaly has been pointed out to me by my colleagues a number of times. While the other teams ratings seem generally consistent with final finishing position, the Crusaders manage to be quite different. This is due to their habit of not losing by much and winning by a lot, and their consistently strong performance over a number of years. They did well towards the end of the season also compared to the beginning of the season. I am contemplating adjusting their rating for the start of the next season, but I am reluctant to make ad hoc changes. The point of my ratings is to use a totally algorithmic data-driven method. I have investigated a different approach using a method which just considers win or loss rather than the score difference, which is another possible approach to dealing with this anomaly.
As for total rating point decrease, that is possibly due to the presence of a shrinkage factor for the difference in scores when the difference is over a certain threshold.
Regarding the way older results affect the ratings, the effect of older results reduces exponentially over time—the basic method being exponential smoothing. The smoothing constant is such though that the decline is not particularly rapid, which is why the Crusaders’ past performance helps boost their rating.
9 years ago
Hi David,
Are you planning to do the Currie cup again this year
9 years ago
Yes. When does the premier division start? I see there are some qualifying matches first, so presumably until they are sorted there is no full fixture list.
9 years ago
Yes it will start +- the weekend 7th of Aug 2015
thanks
9 years ago