Posts filed under Sports statistics (244)

May 20, 2015

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
Roosters 9.18 9.09 0.10
Cowboys 7.37 9.52 -2.20
Rabbitohs 6.05 13.06 -7.00
Storm 5.13 4.36 0.80
Broncos 3.81 4.03 -0.20
Dragons 2.04 -1.74 3.80
Panthers 1.01 3.69 -2.70
Warriors 0.85 3.07 -2.20
Knights -1.67 -0.28 -1.40
Raiders -1.82 -7.09 5.30
Sea Eagles -2.10 2.68 -4.80
Bulldogs -2.14 0.21 -2.30
Sharks -5.61 -10.76 5.10
Eels -6.88 -7.19 0.30
Wests Tigers -6.90 -13.13 6.20
Titans -6.97 -8.20 1.20

 

Performance So Far

So far there have been 80 matches played, 44 of which were correctly predicted, a success rate of 55%.

Here are the predictions for last week’s games.

Game Date Score Prediction Correct
1 Bulldogs vs. Roosters May 15 10 – 24 -7.30 TRUE
2 Cowboys vs. Broncos May 15 31 – 20 5.80 TRUE
3 Eels vs. Warriors May 16 13 – 17 -3.70 TRUE
4 Storm vs. Rabbitohs May 16 16 – 12 1.70 TRUE
5 Titans vs. Sharks May 16 22 – 23 2.10 FALSE
6 Dragons vs. Raiders May 17 32 – 18 5.70 TRUE
7 Knights vs. Wests Tigers May 17 22 – 12 7.90 TRUE
8 Sea Eagles vs. Panthers May 18 10 – 11 0.10 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 Rabbitohs vs. Eels May 22 Rabbitohs 15.90
2 Wests Tigers vs. Cowboys May 23 Cowboys -11.30
3 Raiders vs. Bulldogs May 24 Raiders 3.30
4 Knights vs. Broncos May 25 Broncos -2.50

 

Super 15 Predictions for Round 15

Team Ratings for Round 15

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 6.20 10.00 -3.80
Hurricanes 5.54 2.89 2.60
Chiefs 4.44 2.23 2.20
Brumbies 4.16 2.20 2.00
Highlanders 2.77 -2.54 5.30
Bulls 2.73 2.88 -0.10
Stormers 2.35 1.68 0.70
Blues -0.44 1.44 -1.90
Sharks -1.94 3.91 -5.90
Lions -3.00 -3.39 0.40
Rebels -4.59 -9.53 4.90
Force -4.80 -4.67 -0.10
Cheetahs -6.69 -5.55 -1.10
Reds -8.61 -4.98 -3.60

 

Performance So Far

So far there have been 92 matches played, 60 of which were correctly predicted, a success rate of 65.2%.

Here are the predictions for last week’s games.

Game Date Score Prediction Correct
1 Blues vs. Bulls May 15 23 – 18 0.70 TRUE
2 Reds vs. Rebels May 15 46 – 29 -2.20 FALSE
3 Hurricanes vs. Chiefs May 16 22 – 18 5.30 TRUE
4 Waratahs vs. Sharks May 16 33 – 18 12.10 TRUE
5 Lions vs. Brumbies May 16 20 – 30 -1.60 TRUE
6 Cheetahs vs. Highlanders May 16 24 – 45 -2.90 TRUE

 

Predictions for Round 15

Here are the predictions for Round 15. 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 Chiefs vs. Bulls May 22 Chiefs 6.20
2 Reds vs. Sharks May 22 Sharks -2.20
3 Blues vs. Hurricanes May 23 Hurricanes -2.00
4 Waratahs vs. Crusaders May 23 Waratahs 1.80
5 Force vs. Highlanders May 23 Highlanders -3.10
6 Cheetahs vs. Lions May 23 Cheetahs 0.30
7 Stormers vs. Rebels May 23 Stormers 11.40

 

May 13, 2015

NRL Predictions for Round 10

Team Ratings for Round 10

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
Roosters 8.69 9.09 -0.40
Cowboys 6.99 9.52 -2.50
Rabbitohs 6.22 13.06 -6.80
Storm 4.95 4.36 0.60
Broncos 4.20 4.03 0.20
Dragons 1.44 -1.74 3.20
Panthers 0.93 3.69 -2.80
Warriors 0.82 3.07 -2.30
Raiders -1.22 -7.09 5.90
Bulldogs -1.66 0.21 -1.90
Knights -1.83 -0.28 -1.60
Sea Eagles -2.02 2.68 -4.70
Sharks -5.85 -10.76 4.90
Titans -6.74 -8.20 1.50
Wests Tigers -6.74 -13.13 6.40
Eels -6.85 -7.19 0.30

 

Performance So Far

So far there have been 72 matches played, 38 of which were correctly predicted, a success rate of 52.8%.

Here are the predictions for last week’s games.

Game Date Score Prediction Correct
1 Broncos vs. Panthers May 08 8 – 5 6.80 TRUE
2 Roosters vs. Wests Tigers May 08 36 – 4 16.20 TRUE
3 Cowboys vs. Bulldogs May 09 23 – 16 12.40 TRUE
4 Raiders vs. Titans May 09 56 – 16 3.70 TRUE
5 Sharks vs. Warriors May 09 16 – 20 -2.40 TRUE
6 Eels vs. Storm May 10 10 – 28 -7.30 TRUE
7 Sea Eagles vs. Knights May 10 30 – 28 3.00 TRUE
8 Rabbitohs vs. Dragons May 11 16 – 10 8.10 TRUE

 

Predictions for Round 10

Here are the predictions for Round 10. 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 Bulldogs vs. Roosters May 15 Roosters -7.30
2 Cowboys vs. Broncos May 15 Cowboys 5.80
3 Eels vs. Warriors May 16 Warriors -3.70
4 Storm vs. Rabbitohs May 16 Storm 1.70
5 Titans vs. Sharks May 16 Titans 2.10
6 Dragons vs. Raiders May 17 Dragons 5.70
7 Knights vs. Wests Tigers May 17 Knights 7.90
8 Sea Eagles vs. Panthers May 18 Sea Eagles 0.10

 

Super 15 Predictions for Round 14

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

 

May 6, 2015

Super 15 Predictions for Round 13

Team Ratings for Round 13

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 7.73 10.42 -2.70
Waratahs 6.87 10.00 -3.10
Hurricanes 5.98 2.89 3.10
Chiefs 4.32 2.23 2.10
Brumbies 3.36 2.20 1.20
Bulls 3.04 2.88 0.20
Stormers 2.60 1.68 0.90
Highlanders 2.09 -2.54 4.60
Blues 0.43 1.44 -1.00
Sharks -2.00 3.91 -5.90
Lions -2.83 -3.39 0.60
Rebels -4.66 -9.53 4.90
Cheetahs -5.64 -5.55 -0.10
Force -5.74 -4.67 -1.10
Reds -8.56 -4.98 -3.60

 

Performance So Far

So far there have been 80 matches played, 52 of which were correctly predicted, a success rate of 65%.

Here are the predictions for last week’s games.

Game Date Score Prediction Correct
1 Highlanders vs. Sharks May 01 48 – 15 5.60 TRUE
2 Brumbies vs. Waratahs May 01 10 – 13 1.10 FALSE
3 Blues vs. Force May 02 41 – 24 9.70 TRUE
4 Hurricanes vs. Crusaders May 02 29 – 23 1.60 TRUE
5 Rebels vs. Chiefs May 02 16 – 15 -5.30 FALSE
6 Cheetahs vs. Stormers May 02 25 – 17 -5.90 FALSE
7 Bulls vs. Lions May 02 35 – 33 11.00 TRUE

 

Predictions for Round 13

Here are the predictions for Round 13. 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 Crusaders vs. Reds May 08 Crusaders 20.80
2 Rebels vs. Blues May 08 Blues -0.60
3 Hurricanes vs. Sharks May 09 Hurricanes 12.50
4 Force vs. Waratahs May 09 Waratahs -8.60
5 Lions vs. Highlanders May 09 Highlanders -0.40
6 Stormers vs. Brumbies May 09 Stormers 3.70

 

All-Blacks birth month

This graphic and the accompanying story in the Herald produced a certain amount of skeptical discussion on Twitter today.

AB2

It looks a bit as though there is an effect of birth month, and the Herald backs this up with citations to Malcolm Gladwell on ice hockey.

The first question is whether there is any real evidence of a pattern. There is, though it’s not overwhelming. If you did this for random sets of 173 people, about 1 in 80 times there would be 60 or more in the same quarter (and yes, I did use actual birth frequencies rather than just treating all quarters as equal). The story also looks at the Black Caps, where evidence is a lot weaker because the numbers are smaller.

On the other hand, we are comparing to a pre-existing hypothesis here. If you asked whether the data were a better fit to equal distribution over quarters or to Gladwell’s ice-hockey statistic of a majority in the first quarter, they are a much better fit to equal distribution over quarters.

The next step is to go slightly further than Gladwell, who is not (to put it mildly) a primary source. The fact that he says there is a study showing X is good evidence that there is a study showing X, but it isn’t terribly good evidence that X is true. His books are written to communicate an idea, not to provide balanced reporting or scientific reference.  The hockey analysis he quotes was the first study of the topic, not the last word.

It turns out that even for ice-hockey things are more complicated

Using publically available data of hockey players from 2000–2009, we find that the relative age effect, as described by Nolan and Howell (2010) and Gladwell (2008), is moderate for the average Canadian National Hockey League player and reverses when examining the most elite professional players (i.e. All-Star and Olympic Team rosters).

So, if you expect the ice-hockey phenomenon to show up in New Zealand, the ‘most elite professional players’, the All Blacks might be the wrong place to look.

On the other hand Rugby League in the UK does show very strong relative age effects even into the national teams — more like the 50% in first quarter that Gladwell quotes for ice hockey. Further evidence that things are more complicated comes from soccer. A paper (PDF) looking at junior and professional soccer found imbalances in date of birth, again getting weaker at higher levels. They also had an interesting natural experiment when the eligibility date changed in Australia, from January 1 to August 1.

soccer

As the graph shows, the change in eligibility date was followed by a change in birth-date distribution, but not how you might expect. An August 1 cutoff saw a stronger first-quarter peak than the January 1 cutoff.

Overall, it really does seem to be true that relative age effects have an impact on junior sports participation, and possibly even high-level professional acheivement. You still might not expect the ‘majority born in the first quarter’ effect to translate from the NHL as a whole to the All Blacks, and the data suggest it doesn’t.

Rather more important, however, are relative age effects in education. After all, there’s a roughly 99.9% chance that your child isn’t going to be an All Black, but education is pretty much inevitable. There’s similar evidence that the school-age cutoff has an effect on educational attainment, which is weaker than the sports effects, but impacts a lot more people. In Britain, where the school cutoff is September 1:

Analysis shows that approximately 6% fewer August-born children reached the expected level of attainment in the 3 core subjects at GCSE (English, mathematics and science) relative to September-born children (August born girls 55%; boys 44%; September born girls 61% boys 50%)

In New Zealand, with a March 1 cutoff, you’d expect worse average school performance for kids born on the dates the Herald story is recommending.

As with future All Blacks, the real issue here isn’t when to conceive. The real issue is that the system isn’t working as well for some people. The All Blacks (or more likely the Blues) might play better if they weren’t missing key players born in the wrong month. The education system, at least in the UK, would work better if it taught all children as well as it teaches those born in autumn.  One of these matters.

 

 

April 29, 2015

NRL Predictions for Round 9

Team Ratings for Round 9

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
Roosters 7.59 9.09 -1.50
Cowboys 7.39 9.52 -2.10
Rabbitohs 6.39 13.06 -6.70
Broncos 4.48 4.03 0.40
Storm 4.19 4.36 -0.20
Dragons 1.27 -1.74 3.00
Warriors 0.70 3.07 -2.40
Panthers 0.64 3.69 -3.10
Knights -1.91 -0.28 -1.60
Sea Eagles -1.94 2.68 -4.60
Bulldogs -2.06 0.21 -2.30
Raiders -3.64 -7.09 3.40
Titans -4.31 -8.20 3.90
Wests Tigers -5.64 -13.13 7.50
Sharks -5.72 -10.76 5.00
Eels -6.09 -7.19 1.10

 

Performance So Far

So far there have been 64 matches played, 30 of which were correctly predicted, a success rate of 46.9%.

Here are the predictions for last week’s games.

Game Date Score Prediction Correct
1 Bulldogs vs. Wests Tigers Apr 24 14 – 38 11.30 FALSE
2 Broncos vs. Eels Apr 25 28 – 16 13.90 TRUE
3 Knights vs. Cowboys Apr 25 24 – 26 -7.00 TRUE
4 Roosters vs. Dragons Apr 25 12 – 14 11.20 FALSE
5 Storm vs. Sea Eagles Apr 25 10 – 12 11.00 FALSE
6 Warriors vs. Titans Apr 25 28 – 32 11.10 FALSE
7 Panthers vs. Sharks Apr 26 26 – 18 9.60 TRUE
8 Rabbitohs vs. Raiders Apr 26 22 – 30 16.40 FALSE

 

Predictions for Round 9

Here are the predictions for Round 9. 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. Panthers May 08 Broncos 6.80
2 Roosters vs. Wests Tigers May 08 Roosters 16.20
3 Cowboys vs. Bulldogs May 09 Cowboys 12.40
4 Raiders vs. Titans May 09 Raiders 3.70
5 Sharks vs. Warriors May 09 Warriors -2.40
6 Eels vs. Storm May 10 Storm -7.30
7 Sea Eagles vs. Knights May 10 Sea Eagles 3.00
8 Rabbitohs vs. Dragons May 11 Rabbitohs 8.10

 

Super 15 Predictions for Round 12

Team Ratings for Round 12

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 8.05 10.42 -2.40
Waratahs 6.58 10.00 -3.40
Hurricanes 5.66 2.89 2.80
Chiefs 4.75 2.23 2.50
Brumbies 3.65 2.20 1.40
Bulls 3.63 2.88 0.80
Stormers 3.44 1.68 1.80
Highlanders 0.59 -2.54 3.10
Blues -0.06 1.44 -1.50
Sharks -0.50 3.91 -4.40
Lions -3.42 -3.39 -0.00
Rebels -5.09 -9.53 4.40
Force -5.25 -4.67 -0.60
Cheetahs -6.48 -5.55 -0.90
Reds -8.56 -4.98 -3.60

 

Performance So Far

So far there have been 73 matches played, 48 of which were correctly predicted, a success rate of 65.8%.

Here are the predictions for last week’s games.

Game Date Score Prediction Correct
1 Chiefs vs. Force Apr 24 35 – 27 15.50 TRUE
2 Brumbies vs. Highlanders Apr 24 31 – 18 6.70 TRUE
3 Crusaders vs. Blues Apr 25 29 – 15 11.70 TRUE
4 Waratahs vs. Rebels Apr 25 18 – 16 17.50 TRUE
5 Lions vs. Cheetahs Apr 25 34 – 29 7.50 TRUE
6 Stormers vs. Bulls Apr 25 15 – 13 4.20 TRUE
7 Reds vs. Hurricanes Apr 26 19 – 35 -8.80 TRUE

 

Predictions for Round 12

Here are the predictions for Round 12. 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 Highlanders vs. Sharks May 01 Highlanders 5.60
2 Brumbies vs. Waratahs May 01 Brumbies 1.10
3 Blues vs. Force May 02 Blues 9.70
4 Hurricanes vs. Crusaders May 02 Hurricanes 1.60
5 Rebels vs. Chiefs May 02 Chiefs -5.30
6 Cheetahs vs. Stormers May 02 Stormers -5.90
7 Bulls vs. Lions May 02 Bulls 11.00

 

April 22, 2015

NRL Predictions for Round 8

Team Ratings for Round 8

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
Roosters 8.52 9.09 -0.60
Rabbitohs 8.05 13.06 -5.00
Cowboys 7.76 9.52 -1.80
Storm 5.11 4.36 0.80
Broncos 4.63 4.03 0.60
Warriors 1.75 3.07 -1.30
Panthers 0.77 3.69 -2.90
Dragons 0.35 -1.74 2.10
Bulldogs 0.31 0.21 0.10
Knights -2.28 -0.28 -2.00
Sea Eagles -2.85 2.68 -5.50
Raiders -5.31 -7.09 1.80
Titans -5.36 -8.20 2.80
Sharks -5.85 -10.76 4.90
Eels -6.24 -7.19 0.90
Wests Tigers -8.00 -13.13 5.10

 

Performance So Far

So far there have been 56 matches played, 27 of which were correctly predicted, a success rate of 48.2%.

Here are the predictions for last week’s games.

Game Date Score Prediction Correct
1 Bulldogs vs. Sea Eagles Apr 17 28 – 16 5.20 TRUE
2 Dragons vs. Broncos Apr 17 12 – 10 -1.90 FALSE
3 Cowboys vs. Warriors Apr 18 28 – 24 11.00 TRUE
4 Storm vs. Roosters Apr 18 17 – 16 -0.70 FALSE
5 Titans vs. Panthers Apr 18 32 – 6 -7.60 FALSE
6 Knights vs. Eels Apr 19 22 – 28 9.10 FALSE
7 Wests Tigers vs. Raiders Apr 19 22 – 30 1.70 FALSE
8 Sharks vs. Rabbitohs Apr 20 18 – 10 -13.90 FALSE

 

Predictions for Round 8

Here are the predictions for Round 8. 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 Bulldogs vs. Wests Tigers Apr 24 Bulldogs 11.30
2 Broncos vs. Eels Apr 25 Broncos 13.90
3 Knights vs. Cowboys Apr 25 Cowboys -7.00
4 Roosters vs. Dragons Apr 25 Roosters 11.20
5 Storm vs. Sea Eagles Apr 25 Storm 11.00
6 Warriors vs. Titans Apr 25 Warriors 11.10
7 Panthers vs. Sharks Apr 26 Panthers 9.60
8 Rabbitohs vs. Raiders Apr 26 Rabbitohs 16.40

 

Super 15 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
Crusaders 7.84 10.42 -2.60
Waratahs 7.50 10.00 -2.50
Chiefs 5.25 2.23 3.00
Hurricanes 5.18 2.89 2.30
Stormers 3.64 1.68 2.00
Bulls 3.43 2.88 0.60
Brumbies 3.22 2.20 1.00
Highlanders 1.02 -2.54 3.60
Blues 0.15 1.44 -1.30
Sharks -0.50 3.91 -4.40
Lions -3.19 -3.39 0.20
Force -5.75 -4.67 -1.10
Rebels -6.02 -9.53 3.50
Cheetahs -6.71 -5.55 -1.20
Reds -8.08 -4.98 -3.10

 

Performance So Far

So far there have been 66 matches played, 41 of which were correctly predicted, a success rate of 62.1%.

Here are the predictions for last week’s games.

Game Date Score Prediction Correct
1 Crusaders vs. Chiefs Apr 17 9 – 26 9.50 FALSE
2 Hurricanes vs. Waratahs Apr 18 24 – 29 3.30 FALSE
3 Highlanders vs. Blues Apr 18 30 – 24 4.60 TRUE
4 Brumbies vs. Rebels Apr 18 8 – 13 15.60 FALSE
5 Force vs. Stormers Apr 18 6 – 13 -4.40 TRUE
6 Sharks vs. Bulls Apr 18 10 – 17 1.10 FALSE
7 Cheetahs vs. Reds Apr 18 17 – 18 6.90 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 Chiefs vs. Force Apr 24 Chiefs 15.50
2 Brumbies vs. Highlanders Apr 24 Brumbies 6.70
3 Crusaders vs. Blues Apr 25 Crusaders 11.70
4 Waratahs vs. Rebels Apr 25 Waratahs 17.50
5 Lions vs. Cheetahs Apr 25 Lions 7.50
6 Stormers vs. Bulls Apr 25 Stormers 4.20
7 Reds vs. Hurricanes Apr 26 Hurricanes -8.80