March 4, 2015

NRL Predictions for Round 1

Team Ratings for Round 1

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 13.06 13.06 -0.00
Cowboys 9.52 9.52 -0.00
Roosters 9.09 9.09 -0.00
Storm 4.36 4.36 0.00
Broncos 4.03 4.03 -0.00
Panthers 3.69 3.69 -0.00
Warriors 3.07 3.07 -0.00
Sea Eagles 2.68 2.68 0.00
Bulldogs 0.21 0.21 0.00
Knights -0.28 -0.28 -0.00
Dragons -1.74 -1.74 -0.00
Raiders -7.09 -7.09 -0.00
Eels -7.19 -7.19 -0.00
Titans -8.20 -8.20 0.00
Sharks -10.76 -10.76 -0.00
Wests Tigers -13.13 -13.13 -0.00

 

Predictions for Round 1

Here are the predictions for Round 1. 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 Broncos vs. Rabbitohs Mar 05 Rabbitohs -6.00
2 Eels vs. Sea Eagles Mar 06 Sea Eagles -6.90
3 Cowboys vs. Roosters Mar 07 Cowboys 3.40
4 Knights vs. Warriors Mar 07 Knights 0.70
5 Titans vs. Wests Tigers Mar 07 Titans 7.90
6 Panthers vs. Bulldogs Mar 08 Panthers 6.50
7 Sharks vs. Raiders Mar 08 Raiders -0.70
8 Dragons vs. Storm Mar 09 Storm -3.10

 

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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
    Ken Mant Nath

    Hi David, I don’t get Game 4: Knights – 0.28, Warriors 3.07 = Prediction Knights 0.70. Could you help me by spelling out the maths in English (rather than algebra)? Kind regards, Ken

    9 years ago

  • avatar

    The difference is due to the home ground advantage, which for this match was 4 points:
    – 0.23 – 3.07 + 4 = 0.65. I actually keep more decimal places when I do this sum though so the value given in the post is slightly different, that is 0.70 rather than the value 0.65 calculated above.

    9 years ago

    • avatar
      Ken Mant Nath

      The other games I assumed a Home Advantage (HA) of 3 points for. This worked for all but Knights-Warriors match. I was obviously wrong with assumption because the math wouldn’t work using HA 3. You say HA ‘for this match was 4 points’. Therefore, David, I ask why was HA for this match 4 points? Why did HA value vary for this match? Will HA value vary match to match (3,4 or 5 or so) depending on value you assign?

      9 years ago

      • avatar

        There are two different values, one for games involving two teams from the same country, another if the two teams are from different countries. For the NRL, that means games involving the Warriors have a different value to other games.

        9 years ago

  • avatar
    Ken Mant Nath

    Thank you kindly.

    9 years ago