Posts from March 2023 (19)

Team Ratings for Round 21

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 97 matches played, 67 of which were correctly predicted, a success rate of 69.1%.
Here are the predictions for last week’s games.

Predictions for Round 21

Here are the predictions for Round 21. 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 2

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 8 matches played, 6 of which were correctly predicted, a success rate of 75%.
Here are the predictions for last week’s games.

Predictions for Round 2

Here are the predictions for Round 2. 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 16

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 120 matches played, 87 of which were correctly predicted, a success rate of 72.5%.
Here are the predictions for last week’s games.

Predictions for Week 16

Here are the predictions for Week 16. 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 21

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 140 matches played, 102 of which were correctly predicted, a success rate of 72.9%.
Here are the predictions for last week’s games.

Predictions for Round 21

Here are the predictions for Round 21. 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 3

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 12 matches played, 9 of which were correctly predicted, a success rate of 75%.
Here are the predictions for last week’s games.

Predictions for Week 3

Here are the predictions for Week 3. 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 20

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 92 matches played, 63 of which were correctly predicted, a success rate of 68.5%.
Here are the predictions for last week’s games.

Predictions for Round 20

Here are the predictions for Round 20. 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.

From Stuff: Japan just found 7000 islands it never knew existed

That’s not quite what happened, as the story goes on to say.  We’re not talking about Kupe discovering Aotearoa or even Abel Tasman ‘discovering’ New Zealand.  There are three main groups of ‘new’ islands:

• Pairs or small groups of islands that were counted as a single island before and are now recognised as multiple separate islands.
• Islands in rivers or lakes, which were known about before but not part of the previous count
• Large sandbars, which were known about before, but used not to be included in the definition of ‘island’

There are also islands genuinely appearing and disappearing, because of volcanic activity and erosion, but that’s a tiny fraction of the discrepancy.

Counting things requires both a definition of the thing to be counted and good enough measurement to see and recognise them.  In other news, the New Zealand Census is on!

There’s been a scary news story about an artificial sweetener that previously looked remarkably inoffensive, erythritol.  It’s produced by fermentation of various plant material, and it comes in ‘organic’ as well as normal versions; it’s got similar taste and feel to sugar, and you can even use it for baking.  So when someone reports that it increases the risk of heart attack by a lot, you’d hope they had investigated thoroughly.

The researchers didn’t particularly have it in for erythritol; they were looking at blood components to see if anything predicted heart attack by a useful amount, and found a dramatic correlation with the amount of erythritol in the blood — and I mean dramatic. Here’s the chart showing the percentage of people who didn’t have a heart attack over the three years after their blood measurement, divided into four equal groups based on erythritol in the blood:

It’s not quite as bad as it first looks — the y-axis only goes down to 80% — but it still suggests more than half of heart attacks are due to erythritol, making it almost as bad as smoking. And also that there’s a magic threshold between safe and dangerous doses. This is … hard to believe? Now, this was the group where they discovered the correlation, so you’d expect over-estimation.  Not being completely irresponsible, they did check in other groups of people. Here’s a separate US group

It’s not quite as dramatic, but we’re still looking at a doubling of risk in the highest group and no real difference between the other three. And we’re still looking at nearly half of heart attacks being due to this obscure artificial sweetener.

So it is credible?

One question to ask is whether there’s a mechanism for it to be dangerous — this isn’t a definitive criterion, because there’s a lot we don’t know, but it’s useful.  The researchers say that erythritol makes platelets more likely to clump together, triggering clots, which is a thing that can happen and would increase heart attack risk — that’s why aspirin, which disables platelets, has been recommended to prevent heart attacks.

Another question to ask is whether the high erythritol group got it from eating the most erythritol. If they aren’t, this isn’t going to give useful dietary advice.  The compound is made in the body to some extent, and it’s excreted via the kidneys. Could people at higher risk of heart attack be making more internally or excreting it less effectively?  The natural step here would be to feed healthy people some erythritol and see what happens to their platelets.  That study is apparently underway, though it’s small and has no control group.

You might also ask if there has been a dramatic increase in heart attacks over the time that erythritol has become more popular in foods?  There hasn’t been, though a moderate increase might have been masked by all the other factors causing decreases in risk.

I would be surprised if the risk turns out to really be this big, though it’s entirely possible that there’s some risk. At least the platelet study should be reasonably informative, and it’s a pity it wasn’t done before the publicity.

There are other issues with this graph (from the ABC’s Dan Ziffer): these are components of inflation rather than causes, why ‘beyond 3%’?  The big issue, though, is the pie, where the positive number add to 104% and then there’s the negative 4%.

You can’t have negative numbers in a pie chart; that isn’t how pies work.  If you combine 104% of a pie and 4% of an anti-pie, you’ll end up on this list