Stats Chat

The 1 in 3 figure, as Tava Olsen reminded us on Twitter, is the proportion of homes that are rented.  The proportion of people is probably higher, but it’s surprisingly hard to tell. I’m going to outsource this to me from 2017, when it was a Stat-of-the-Week nomination.

The Bird of the Year contest, run by wildlife advocate Forest & Bird, asks the public to vote for their favourite New Zealand native bird. People get very excited by this, with campaigns coalescing around particular birds and much trash-talk between rival camps.

This year, the race was between the kākāpō and the hoiho or yellow-eyed penguin. Find out which bird won and what voting looked like on the way there in a neat little data visualisation by Yvan Richard of Dragonfly Data Science here. Read a story about this year’s race here. #BirdoftheYear

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 24 matches played, 18 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.

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 42 matches played, 35 of which were correctly predicted, a success rate of 83.3%.
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 Round 4

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 18 matches played, 14 of which were correctly predicted, a success rate of 77.8%.
Here are the predictions for last week’s games.

Predictions for Round 4

Here are the predictions for Round 4. 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 35 matches played, 29 of which were correctly predicted, a success rate of 82.9%.
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.

• Radio NZ talks to Chris McDowall and Tim Denee about their new atlas of Aotearoa, We Are Here.
• Kieran Healy maps dog breeds in New York — and talks about colour choice for the maps
• Janelle Shane’s Ted talk on AI weirdness.
• “There was a statistic going around that said 1 in 6 millennials have at least $100,000 saved.” Nathan Yau actually looks at the numbers.
• From Ars Technica, “A health care algorithm offered less care to black patients”
• Terrible election graphs are an international problem: here, from Canada
  

From the Herald: Most Norfolk Islanders want to cut ties with Australia and join New Zealand – survey

The second sentence of the piece: “The rebels outnumber those who want free association with Australia, with 37% of the vote compared to 35%.”

We don’t usually consider 37% as ‘most’.

With a little searching, you can find the primary source: the website of Norfolk Island People for Democracy  Most people who responded don’t like the current system, and they are roughly evenly split between full independence, a looser association with Australia giving local control of domestic affairs, or a similarly loose association with New Zealand.

Also, it looks like an online clicky poll.  We’d usually just dismiss these, but there were 450 responses and the Island has a population of only 1800.  If they took reasonable care to make sure the votes were one to a person and from the local population, the numbers are worth paying attention to.  Even if you made the extreme assumption that everyone who didn’t take part supported the status quo, 415 wanting to change it is a substantial fraction.

Q: Did you see that asthma inhalers cause as much greenhouse gas emission as eating meat?

A: Yes

Q: That’s huge!! It’s like 15% of global warming!

A: No

Q: Yes!

A: No. The BBC claim is that the CO₂ equivalent of one person‘s use of asthma inhalers is comparable to one person‘s meat consumption. A lot more people eat meat than use asthma inhalers.

Q: Oh. That’s still quite a lot, though?

A: They say it’s about 4% of emissions from the UK healthcare system. About 0.15% of the UK total.

Q: And compared to meat?

A: Well, the BBC don’t link, but if you find the research paper (PDF) and follow its link for the meat claim, you get a graph saying about 0.9 tonnes CO₂ equivalent per year for an average person switching to a plant-based diet in the UK, compared to the 165kg average they’re claiming for the inhalers (range of 150-400kg).

Q: Isn’t 165kg less than 0.9 tonnes?

A: Yes, quite a bit less.

Q: So why do they get away with that in a published research paper?

A: It’s not the point of the paper. The point is to look at the financial cost of the National Health System switching to asthma inhalers that don’t use greenhouse gases, for the subset of people who can use them.  The costs aren’t that bad. They also suggest other sensible ways to reduce emissions, such as recycling or incinerating used inhalers, and labelling them with the number of doses so that they don’t get discarded early.

Q: What are we doing about this in New Zealand?

A: A bit more than for meat.  There’s an actual plan to reduce total imports of these synthetic greenhouse gases starting now and going through 2036, but in the short term that’s mostly going to affect air conditioners, not inhalers. Pharmac asked for bids for asthma inhaler supply through 2023, and (earlier this month) proposed settling on two products with HFC-134a propellant, which is the less-bad of the two greenhouse gases currently used in inhalers. 

Q: If the point is financial costs, isn’t the comparison with meat just trolling?

A: Pretty much.  Eating plants is an individual choice, it’s not an all-or-nothing change, it doesn’t take a doctor’s prescription, and you don’t need to have asthma to do it.  You could just decide to eat less meat, or give up beef, or your whole household could eat less  meat. And eating less meat doesn’t have negative health implications.

Q: So people should just use their inhalers like their doctor says?

A: Absolutely.  Modern preventer inhalers are a major achievement of medical and chemical science.  For any individual, there should be many possible lifestyle changes higher up your priority list than worrying about your model of asthma inhaler.  Maybe get ready to lobby Pharmac to take emissions into account when they next put out a bid for inhalers,  in 2022 or thereabouts.

Team Ratings for the Rugby World Cup Final

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 Rugby World Cup.

Performance So Far

So far there have been 43 matches played, 39 of which were correctly predicted, a success rate of 90.7%.
Here are the predictions for last week’s games.

Predictions for the Rugby World Cup Final

Here are the predictions for the Rugby World Cup Final. 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.