NRL Predictions for Round 11
Team Ratings for Round 11
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 | |
|---|---|---|---|
| Rabbitohs | 12.18 | 9.35 | 2.80 |
| Panthers | 11.03 | 12.99 | -2.00 |
| Storm | 5.97 | 11.21 | -5.20 |
| Eels | 3.42 | 6.78 | -3.40 |
| Roosters | 3.31 | 7.64 | -4.30 |
| Sharks | 2.86 | 4.50 | -1.60 |
| Raiders | 1.01 | 1.98 | -1.00 |
| Broncos | 0.46 | -5.92 | 6.40 |
| Cowboys | -0.19 | 6.23 | -6.40 |
| Dragons | -2.20 | -2.73 | 0.50 |
| Dolphins | -4.58 | -10.00 | 5.40 |
| Titans | -4.79 | -6.32 | 1.50 |
| Sea Eagles | -5.74 | -5.26 | -0.50 |
| Warriors | -6.50 | -11.12 | 4.60 |
| Bulldogs | -8.07 | -8.29 | 0.20 |
| Knights | -10.04 | -9.53 | -0.50 |
| Wests Tigers | -10.12 | -13.52 | 3.40 |
Performance So Far
So far there have been 80 matches played, 45 of which were correctly predicted, a success rate of 56.2%.
Here are the predictions for last week’s games.
| Game | Date | Score | Prediction | Correct | |
|---|---|---|---|---|---|
| 1 | Bulldogs vs. Raiders | May 05 | 30 – 34 | -10.00 | TRUE |
| 2 | Sea Eagles vs. Broncos | May 05 | 6 – 32 | -6.90 | TRUE |
| 3 | Warriors vs. Panthers | May 06 | 6 – 18 | -18.50 | TRUE |
| 4 | Sharks vs. Dolphins | May 06 | 16 – 36 | 7.60 | FALSE |
| 5 | Storm vs. Rabbitohs | May 06 | 12 – 28 | -4.70 | TRUE |
| 6 | Wests Tigers vs. Dragons | May 07 | 18 – 16 | -9.50 | FALSE |
| 7 | Roosters vs. Cowboys | May 07 | 6 – 20 | 5.90 | FALSE |
| 8 | Titans vs. Eels | May 07 | 26 – 24 | -9.80 | FALSE |
Predictions for Round 11
Here are the predictions for Round 11. 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 | Storm vs. Broncos | May 11 | Storm | 8.50 |
| 2 | Bulldogs vs. Warriors | May 12 | Bulldogs | 4.40 |
| 3 | Panthers vs. Roosters | May 12 | Panthers | 10.70 |
| 4 | Rabbitohs vs. Wests Tigers | May 13 | Rabbitohs | 25.30 |
| 5 | Cowboys vs. Dragons | May 13 | Cowboys | 5.00 |
| 6 | Raiders vs. Eels | May 13 | Raiders | 0.60 |
| 7 | Knights vs. Titans | May 14 | Titans | -2.20 |
| 8 | Sea Eagles vs. Sharks | May 14 | Sharks | -5.60 |
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 »
Do you have any ideas why the accuracy of the technique is so much lower for the NRL than the various Rugby Union competitions.
There is only one Rugby League competition so it is hard to tell whether the NRL teams are closer in ability or whether there is some underlying aspect of the rules of the game that makes union games more predictable than league.
The rating spread for the NRL looks similar to that of other competitions though.
2 years ago
Good question. I have some thoughts about this.
Over a number of years I have typically been able to predict Rugby results with over 70% accuracy but Rugby League only with accuracy less than 70%.
I also have often seen really surprising results in Rugby League, ones which I would never predict.
The possibilities I see for this are:
Rugby League has a salary cap which may even out the competition. The spread of ratings is perhaps evidence against that.
Set piece is much more important in Rugby (scrums are a ridiculous joke in Rugby League) and teams which are skilled at set piece will have more reliable performance week to week (Brumbies rolling maul springs to mind).
Lower scores and more easy for a penalty to make a difference: tackler holds on too long, defending team has an extra 6 tackles to defend.
Rugby League is corrupt. There is evidence for this in the past. It is fairly easy for an individual to manipulate the result by drawing a penalty in a crucial location. There are players with gambling problems in all sports and in Rugby League there have been publicised links of players with shady characters. I am not saying Rugby League is corrupt, but it is a possibility.
2 years ago