May 13, 2015

Super 15 Predictions for Round 14

By

Team Ratings for Round 14

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 8.89 10.42 -1.50
Waratahs 5.94 10.00 -4.10
Hurricanes 5.66 2.89 2.80
Chiefs 4.32 2.23 2.10
Brumbies 3.60 2.20 1.40
Bulls 3.04 2.88 0.20
Stormers 2.35 1.68 0.70
Highlanders 1.72 -2.54 4.30
Blues -0.75 1.44 -2.20
Sharks -1.68 3.91 -5.60
Lions -2.45 -3.39 0.90
Rebels -3.48 -9.53 6.00
Force -4.80 -4.67 -0.10
Cheetahs -5.64 -5.55 -0.10
Reds -9.72 -4.98 -4.70

 

Performance So Far

So far there have been 86 matches played, 55 of which were correctly predicted, a success rate of 64%.

Here are the predictions for last week’s games.

Game Date Score Prediction Correct
1 Crusaders vs. Reds May 08 58 – 17 20.80 TRUE
2 Rebels vs. Blues May 08 42 – 22 -0.60 FALSE
3 Hurricanes vs. Sharks May 09 32 – 24 12.50 TRUE
4 Force vs. Waratahs May 09 18 – 11 -8.60 FALSE
5 Lions vs. Highlanders May 09 28 – 23 -0.40 FALSE
6 Stormers vs. Brumbies May 09 25 – 24 3.70 TRUE

 

Predictions for Round 14

Here are the predictions for Round 14. 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 Blues vs. Bulls May 15 Blues 0.70
2 Reds vs. Rebels May 15 Rebels -2.20
3 Hurricanes vs. Chiefs May 16 Hurricanes 5.30
4 Waratahs vs. Sharks May 16 Waratahs 12.10
5 Lions vs. Brumbies May 16 Brumbies -1.60
6 Cheetahs vs. Highlanders May 16 Highlanders -2.90

 

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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 »

Comments

  • avatar
    Kenneth Mant Nath

    Why not start 2016 rankings and predictions at zero, especially for rugby league? The current season (one-third over) is a disaster for predictions with 72 matches played : 38 True, 34 False (52%). NRL teams playing at home have fared no better: the home team has won 38, away team won 34.

    Off-season attrition and salary cap adjustment can play havoc with
    last season performance going forward. Moral hazard aside, bookies and sports journalists thrive on rear-view mirror driving.

    9 years ago

    • avatar
      David Scott

      My code does include a shrinkage factor between seasons, so that all ratings are shrunk towards zero. My investigation to find the best values for the parameters did not give anything like the 100% shrinkage factor as you are suggesting.

      This year has been particularly challenging for predicting the NRL. Last time I looked a number of the Sydney Morning Herald’s Expert Tipsters had percentages under 50%.

      9 years ago

  • avatar
    Kenneth Mant Nath

    I support your code and off-season shrinkage factor to make statistically informed predictions in Super 15 Rugby Union and the NRL.

    NRL performance may revert to its norm in the long run, or new norm, since one-third into the 2015 season has been particularly challenging for NRL predictions, and home teams (both 52% true, and below par).

    My comment is NRL management decisions taken at all levels can have unintended consequences for NRL code and statistics.

    9 years ago