Stats Chat

• The Herald has a story on a penis size ‘survey’ from a UK online pharmacy specialising in men’s health, who “used Google data to rank the average penis size of 86 countries – and New Zealand has placed 50th”. That’s not an indication of worrying privacy leaks in Android phones; it seems they did just Google for the results. The pharmacy obviously wants to get publicity because being unknown will be its biggest business problem. In the UK, they did well and got a mention in The Sun. Being in the Herald doesn’t do them much good, though.
• ESR is now publishing detailed wastewater Covid data, which is great — the big advantage of wastewater data is that the sampling is independent of Covid prevalence, in contrast to data on testing, where you tend to miss more cases as the prevalence goes up.
• One thing I don’t like about the current ESR graphs is that they use a log scale for viral load and a linear scale for cases, which is one reason the peak for wastewater looks so much broader than the peak for cases (the other reason is that wastewater measures total active cases, not daily new cases)
  
• Ben Schmidt has made an interactive map of ethnicity in the US, based on Census data — in the sense that it has a dot for each of the 300-odd million people recorded in the Census
• Interesting Twitter thread about the case against the continued existence of Ivory-billed Woodpeckers in the US.  Not precisely statistical, but definitely statistics-adjacent.
• Somewhat dodgy graphic from Labour about housing consents. If this is an area graph, the axis should go down to zero.  It’s not as bad as some I’ve covered in the past, but it’s annoying. The second graph is an edited version where the axis does go down to zero and the areas are meaningful
  

Team Ratings for Round 7

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.

Performance So Far

So far there have been 48 matches played, 35 of which were correctly predicted, a success rate of 72.9%.
Here are the predictions for last week’s games.

Predictions for Round 7

Here are the predictions for Round 7. 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.

Team Ratings for Week 24

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.

Performance So Far

So far there have been 116 matches played, 83 of which were correctly predicted, a success rate of 71.6%.
Here are the predictions for last week’s games.

Predictions for Week 24

Here are the predictions for Week 24. 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.

Team Ratings for Week 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.

Performance So Far

So far there have been 48 matches played, 33 of which were correctly predicted, a success rate of 68.8%.
Here are the predictions for last week’s games.

Predictions for Week 10

Here are the predictions for Week 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.

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.

Performance So Far

So far there have been 26 matches played, 21 of which were correctly predicted, a success rate of 80.8%.
Here are the predictions for last week’s games.

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.

Watch Ross Ihaka talk to Ximena Smith about R and other things:

https://www.teaomaori.news/statistics-legend-ross-ihaka-reflects-on-his-revolutionary-software

Team Ratings for Week 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.

Performance So Far

So far there have been 84 matches played, 31 of which were correctly predicted, a success rate of 36.9%.
Here are the predictions for last week’s games.

Predictions for Week 9

Here are the predictions for Week 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.

Team Ratings for Round 6

For a second week all the result predictions have been correct which seems to have generated a lot of interest and some comments.

Please be aware this is a rare event. I have been predicting Super Rugby and NRL for 10 years and getting all results correct is rare enough but never before have I had all results correct two weeks in a row. For me it is simply an example of a fact about rare events. Even if the probability of an outcome is low, if you repeat the action many times it is likely that the outcome will occur.

Regarding the correctness of my predictions, all I will say is that over the course of a season, it is likely that I will get a bit over 70% of correct results. That is what I have observed over a number of years for different competitions but that can vary a lot as well. For many years I was unable to get to 70% correct predictions for the NRL. Currently my predictions for the Rugby Premiership are only 54% correct.

My purpose in posting these predictions has been to illustrate the efficacy of a very simple statistical method of forecasting.  The predictions are also an illustration of what can happen with random events. It can appear that there is a consistent pattern which can be exploited even over what seems to be a considerable time. Never believe that you can beat randomness: it will come back to bite you.

Against my usual practice I won’t publish or comment on all submitted comments this week.

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.

Performance So Far

So far there have been 40 matches played, 29 of which were correctly predicted, a success rate of 72.5%.
Here are the predictions for last week’s games.

Predictions for Round 6

Here are the predictions for Round 6. 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.

Team Ratings for Week 23

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.

Performance So Far

So far there have been 115 matches played, 83 of which were correctly predicted, a success rate of 72.2%.
Here are the predictions for last week’s games.

Predictions for Week 23

Here are the predictions for Week 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.

Team Ratings for Postponed Games

I will post predictions for this weekend’s game after the postponed game is played tonight.

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.

Performance So Far

So far there have been 42 matches played, 30 of which were correctly predicted, a success rate of 71.4%.
Here are the predictions for last week’s games.

Predictions for Postponed Games

Here are the predictions for Postponed Games. 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.