August 13, 2014

NRL Predictions for Round 23

Team Ratings for Round 23

The basic method is described on my Department home page. I have made some changes to the methodology this year, including shrinking the ratings between seasons.

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 11.06 5.82 5.20
Cowboys 8.75 6.01 2.70
Sea Eagles 7.80 9.10 -1.30
Roosters 5.65 12.35 -6.70
Warriors 5.40 -0.72 6.10
Storm 3.89 7.64 -3.70
Broncos 3.00 -4.69 7.70
Panthers 2.18 -2.48 4.70
Knights -3.05 5.23 -8.30
Dragons -3.11 -7.57 4.50
Bulldogs -3.78 2.46 -6.20
Titans -4.79 1.45 -6.20
Eels -6.28 -18.45 12.20
Sharks -7.97 2.32 -10.30
Raiders -8.92 -8.99 0.10
Wests Tigers -11.62 -11.26 -0.40

 

Performance So Far

So far there have been 160 matches played, 91 of which were correctly predicted, a success rate of 56.9%.

Here are the predictions for last week’s games.

Game Date Score Prediction Correct
1 Rabbitohs vs. Sea Eagles Aug 08 23 – 4 5.20 TRUE
2 Broncos vs. Bulldogs Aug 08 41 – 10 7.10 TRUE
3 Cowboys vs. Wests Tigers Aug 09 64 – 6 18.30 TRUE
4 Knights vs. Storm Aug 09 32 – 30 -3.60 FALSE
5 Eels vs. Raiders Aug 09 18 – 10 6.90 TRUE
6 Warriors vs. Sharks Aug 10 16 – 12 20.90 TRUE
7 Dragons vs. Panthers Aug 10 4 – 16 1.80 FALSE
8 Roosters vs. Titans Aug 11 26 – 18 16.60 TRUE

 

Predictions for Round 23

Here are the predictions for Round 23. 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 Rabbitohs vs. Broncos Aug 14 Rabbitohs 12.60
2 Eels vs. Bulldogs Aug 15 Eels 2.00
3 Raiders vs. Dragons Aug 16 Dragons -1.30
4 Storm vs. Sharks Aug 16 Storm 16.40
5 Wests Tigers vs. Roosters Aug 16 Roosters -12.80
6 Knights vs. Warriors Aug 17 Warriors -4.00
7 Titans vs. Sea Eagles Aug 17 Sea Eagles -8.10
8 Panthers vs. Cowboys Aug 18 Cowboys -2.10

 

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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

    Hi – this is v interesting, glad you developed it. Seems to me that over the past few weeks the predictions have generally been right when the margin is over a lowish threshold (somewhere around the 5-7 points mark?) but mixed/wrong when the predicted margin is small. I wonder if you’ve ever looked back at the track record for predicted margins say >= 5?

    1 month ago Reply

    • avatar

      Well that is what you would expect, to correctly predict the ones where the odds are strongly in your favour as indicated by the predicted points difference being large. So I haven’t investigated that. What I do find surprising is how often a team wins totally against the odds. Week 20 was an extreme case: the Sharks shouldn’t have beaten the Panthers and the Eels shouldn’t have beaten the Titans, but they did. The Storm away to the Broncos were very unlikely to win, but thrashed the home team.

      1 month ago Reply

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