Posts from April 2021 (18)

The AstraZeneca vaccine causes an unusual blood clotting syndrome in about 10 out of a million recipients, and it’s not entirely clear whether the J&J vaccine also does and at what frequency.  Those are small numbers, compared to other risks. In particular,  if you’re in a country with Covid, they are small compared to the risk of getting Covid and having some serious harm as a result. So why has there been so much concern?

There are a few components to the concern, but one underlying commonality: the clotting is unexpected and poorly understood.  Patients turn up with blood clots in unusual places and a shortage of platelets (which you’d normally think of as going with not enough clotting). Some obvious treatments — a standard anticlotting drug (heparin) or a transfusion of platelets — are likely to make things worse, so doctors need to know. There isn’t a really compelling model for how the vaccine causes the problem.

If the risk is 10 in a million, taking the vaccine would still be way safer than not taking it, but a lot of the concerns prompting further urgent investigation would have been whether it’s really only 10 in a million, since we don’t understand (in any detail) what’s going on

• have we missed a bunch of cases — remember that initially the risk was thought to be only about 1 in a million?
• are these just the most serious cases, the tip of the iceberg, with many more milder, but still serious, cases that haven’t been noticed yet?
• are these just the earliest-developing cases, with many more on the way?
• is this a batch problem, with some batches of vaccine potentially having a much higher risk?
• does the problem occur in an identifiable small group of people, who would thus be at much higher risk?

There’s been enough data and enough time now to start being confident that the answer to all these questions is ‘no’.  One might rationally prefer the mRNA vaccines, which don’t have this problem, but if you live somewhere with an active outbreak and the choice was the AZ vaccine now or the Moderna vaccine in a month or two, the clotting risk shouldn’t change your decision — and the fact that it wasn’t kept secret should be reassuring.

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 30 matches played, 21 of which were correctly predicted, a success rate of 70%.
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

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.

Q: Did you see that journalists drink too much, are bad at managing emotions, and operate at a lower level than average, according to a new study?

A: That sounds a bit exaggerated

Q: It’s the headline “Journalists drink too much, are bad at managing emotions, and operate at a lower level than average, according to a new study”

A: What I said

Q: But “The results showed that journalists’ brains were operating at a lower level than the average population, particularly because of dehydration and the tendency of journalists to self-medicate with alcohol, caffeine, and high-sugar foods.”

A: How did they measure brain dehydration?

Q: Don’t I get to ask the leading questions?

A:

Q: How did they measure brain dehydration?

A: They didn’t. It just means they drank less than 8 glasses of water per day, per the usual recommendations

Q: Aren’t those recommendations basically an urban mythl?

A: Yes, they seem to be

Q: How much caffeine was ‘too much’?

A: More than two cups of coffee per day

Q: Does that cause brain dehydration

A: No, not really

Q: What is the daily recommended limit for coffee anyway?

A: There really isn’t one. The European Food Safety Authority looked at this in 2015, and they said basically that four cups a day seemed pretty safe but they didn’t have a basis for giving an upper limit.

Q: There’s a limit for alcohol, though?

A: Yes, “To keep health risks from alcohol to a low level, the UK Chief Medical Officers (CMOs) advise it is safest not to drink more than 14 units a week on a regular basis.” And the journalists drank slightly more than that on average.

Q: What’s the average for non-journalists?

A: Hard to tell, but the proportion drinking more than 14 units/week is about 1 in 3 for men and about 1 in 6 for women in the UK.

Q: So, a bit higher than average but not much higher.  How about these brain things. How big were the differences?

A: The report doesn’t say — it doesn’t give data, just conclusions

Q: How much evidence is there that they are even real, not just chance?

A: The report doesn’t say, though the Business Insider story says “it is not yet peer reviewed, and the sample size is small, so the results should not be taken necessarily as fact.

Q: When will it be peer-reviewed?

A: Well, the story is from 2017 and there’s nothing on PubMed yet, so I’m not holding my breath.

• Henry Cooke for the Dominion Post “A routine report on the Government’s mental health services was delayed for over a year as officials battled behind the scenes over plans to dramatically reduce the amount of data in it”
• A letter in response by Len Cook (former  NZ and UK chief statistician): “Few important agency statistics are prepared in order to comply with a law; rather, they maintain  public trust and inform practitioners in the field of progress and conditions across the populations of importance”
• Kate Newton writes in the Sunday Star-Times about the impact of pre-departure Covid testing, “In the two-and-a-half months prior, the average (mean) case rate was 0.66 new cases per 1000 people in managed isolation and quarantine (MIQ). In the following two-and-a-half months, the daily rate has fallen – but only slightly — to 0.55.”
• Derek Thompson in the Atlantic on vaccine misinformation “In a crowded field of wrongness, one person stands out: Alex Berenson.” 
• Dan Bouk and danah boyd: The technopolitics of the U.S. census “Almost no one notices the processes that produce census data—unless something goes terribly wrong. Susan Leigh Star and Karen Ruhleder argue that this is a defining aspect of infrastructure: it “becomes visible upon breakdown.” In this paper, we unspool the stories of some technical disputes that have from time to time made visible the guts of the census infrastructure and consider some techniques that have been employed to maintain the illusion of a simple, certain count. “

Team Ratings for Week 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.

Performance So Far

So far there have been 26 matches played, 19 of which were correctly predicted, a success rate of 73.1%.
Here are the predictions for last week’s games.

Predictions for Week 8

Here are the predictions for Week 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.

Team Ratings for Round 5

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 32 matches played, 24 of which were correctly predicted, a success rate of 75%.
Here are the predictions for last week’s games.

Predictions for Round 5

Here are the predictions for Round 5. 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.

• Eden Park is the world’s sexiest bald man. Or something like that.   The results are bogus for the obvious reason: Prince William and Eden Park both get a lot of internet coverage, so they will show up on what is basically a count of Google hits.  You might well get the same winners for ‘ugliest bald man’ and ‘least popular cricket ground.  These reports are typically done in order to get some company’s name in the news, and since they typically don’t provide any real information about the numbers, it would be poetic justice to report the claims but just leave out the company name.  Or, better, ignore them.
• Good news: there are clinical trial results for the Pfizer/BioNTech vaccine in children aged 12-15. These still need review based on more detail than just a press release, but it’s quite likely that we’ll be vaccinating this age group by the time we’d get around to them based on risk.  Trials in younger children are just starting; the end date will depend on how bad the pandemic is in the next few months, but might be around the end of the year.
• Books:
  • The Data Journalism Handbook (including open-access version) By a large cast including Aotearoa’s own Prof Tahu Kukutai on Indigenous Data Sovereignty
  • How to Make the World Add Up, by Tim Harford (or, in USA/Canada, The Data Detective). It’s a non-technical book on thinking clearly about numbers: “We need to be open-minded without being gullible, maintaining a healthy scepticism without lapsing into corrosive cynicism. Above all, we need to keep being curious.”. He’s on the Slate Money podcast talking about the book here.