Posts from June 2023 (17)

June 11, 2023

72% of landlords?

Chris Luxon, via Q+A:

“72% of all landlords are Mum & Dad investors… they are not evil property speculators”

This is attracting a lot of comment, because it can be interpreted as two quite different claims: either that the landlord of a randomly chosen rental has a 72% chance of being a “Mum & Dad investor” or that a randomly chosen person or corporation who is a landlord has a 72% chance of being a “Mum & Dad investor”.  Mr Luxon presumably means the latter, which is the more natural statistical interpretation, though (and this is a frequent Statschat theme) not necessarily the most relevant number to the policy question at hand.

Strictly speaking, we don’t have data on the fraction of  landlords who are Mum & Dad investors or evil property speculators. No-one makes landlords report whether they have children, whether they own property for speculation or investment, or even whether they are evil.  Some landlords might be evil and have children and not be speculators!  However, if we follow Kirsty Johnston a few years ago in the Herald in dividing up landlords by the numbers of properties they own, it turns out that (a) most of the actual people who own homes don’t own a lot and (b) the occasional people who each own a lot of homes collectively own a lot of homes.

Proportion of properties owned by people who own

One property – 27.1 per cent
Two properties – 13.2 per cent
Three properties – 6.5 per cent
Four to six properties – 10.7 per cent
Seven to 20 properties – 9.7 per cent
More than 20 properties – 9.4 per cent

Of the people who own more than one property, 52% own only two and 70% own two or three.

The word ‘people’ is important here: homes are also owned by companies.  Companies are definitionally not Mum & Dad investors, but they also aren’t necessarily evil property speculators.  The largest in that Herald story was Housing New Zealand, as it then was, who had 60,000 rental properties, and the category would include some other non-profit providers.  At least some of the people who don’t like landlords feel differently about community housing providers.

And, finally homes are owned by trusts, which is a much more difficulty category to survey, since there isn’t a centralised registry of beneficiaries of trusts. The Herald didn’t even hazard a guess.

So, there’s plenty of room for Chris Luxon’s claim to be largely true. Most landlords are probably small-scale, but the small proportion who aren’t will still add up to a lot of rentals.  However, he almost certainly doesn’t have reliable population data about either the parental status or moral alignment of landlords. Nor is it clear that the typical portfolio size of landlords should be decisive in deciding how to tax and regulate them.  Mum & Dad takeaways still need to follow food safety rules.

June 10, 2023

Chocolate for the brain?

Q: Did you see that chocolate and wine really are good for the brain?

A: Not convinced

Q: A randomised trial, though. 16% improvement in memory!

A: A randomised trial, but not 16% improvement in memory

Q: It’s what the Herald says

A: Well, more precisely, it’s what the Daily Telegraph says

Q: What does the research say?

A: It’s a good trial. People were randomly allocated to either flavanols from cocoa or placebo, and they did tests that are supposed to evaluate memory. The scores of both groups improved about 15% over the trial period. The researchers think this is due to practice.

Q: You mean like how Donald Trump remembered the words he was asked in a cognitive function test?

A: Yes, like that.

Q: But the story says there was a benefit in people who had low-flavanol diets before the study.

A: Yes, there was borderline evidence of a difference between people with high and low levels of flavanols in their urine. But that’s a difference of 0.1 points in average score compared to an average change of about 1 point. Nearly all the change in the treated people also showed up in the placebo group, so only a tiny fraction of it could be an effect of treatment.

Q: Was this the planned analysis of the trial or just something they thought up afterwards?

A: It was one of the planned analyses. One of quite a lot of planned analyses.

Q: That’s ok, isn’t it?

A: It’s ok if you don’t get too excited about borderline results in one of the analyses, yes.

Q: So it doesn’t work?

A: It might work — this is relatively impressive as dietary micronutrient evidence goes.  But if it works, it only works for people with low intakes of tea and apples and cherries and citrus and peppers and chocolate and soy.

Q: <sigh> We don’t really qualify, do we?

A: Probably not.

Q: So if we were eating chocolate primarily for the health effects?

A: We’d still be doing it wrong.

June 7, 2023

Briefly

  • Michael Neilson and Chris Knox at the NZ$ Herald have an excellent look at crime statistics and what you can’t straightforwardly conclude from them
  • Outsourcing:  there was a story about garlic to stop Covid.  Here are responses from a blog at the University of Waikato, and from misinformation.wiki
  • Many French labour regulations start to apply when you have 50 employees, says the Economist, showing the graph on the right that has a big drop in the number of businesses reporting 50 or more employees

    The graph on the left shows the same self-reporting from a different source.  The graph in the middle shows actual numbers of employees estimated using payroll data, with nothing happening at 50 — an interesting difference (from)
June 6, 2023

NRL 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
Panthers 12.24 12.99 -0.80
Rabbitohs 9.09 9.35 -0.30
Eels 4.45 6.78 -2.30
Storm 4.31 11.21 -6.90
Sharks 2.60 4.50 -1.90
Broncos 1.69 -5.92 7.60
Raiders 0.36 1.98 -1.60
Roosters 0.29 7.64 -7.40
Cowboys -0.12 6.23 -6.30
Dragons -2.82 -2.73 -0.10
Sea Eagles -4.59 -5.26 0.70
Warriors -4.81 -11.12 6.30
Dolphins -4.90 -10.00 5.10
Wests Tigers -6.42 -13.52 7.10
Titans -6.79 -6.32 -0.50
Bulldogs -8.08 -8.29 0.20
Knights -8.48 -9.53 1.00

 

Performance So Far

So far there have been 108 matches played, 61 of which were correctly predicted, a success rate of 56.5%.
Here are the predictions for last week’s games.

Game Date Score Prediction Correct
1 Wests Tigers vs. Raiders Jun 02 19 – 20 -4.60 TRUE
2 Warriors vs. Dolphins Jun 03 30 – 8 3.90 TRUE
3 Titans vs. Rabbitohs Jun 03 28 – 46 -11.90 TRUE
4 Sharks vs. Broncos Jun 03 12 – 20 5.70 FALSE
5 Roosters vs. Bulldogs Jun 04 25 – 24 13.00 TRUE
6 Cowboys vs. Storm Jun 04 45 – 20 -4.80 FALSE
7 Panthers vs. Dragons Jun 04 26 – 18 19.60 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 Titans vs. Wests Tigers Jun 08 Titans 2.60
2 Raiders vs. Warriors Jun 09 Raiders 11.20
3 Sea Eagles vs. Dolphins Jun 09 Sea Eagles 3.30
4 Dragons vs. Rabbitohs Jun 10 Rabbitohs -8.90
5 Broncos vs. Knights Jun 10 Broncos 13.20
6 Roosters vs. Panthers Jun 10 Panthers -9.00
7 Storm vs. Sharks Jun 11 Storm 4.70
8 Bulldogs vs. Eels Jun 12 Eels -9.50

 

Top 14 Predictions for the Semi-finals

Team Ratings for the Semi-finals

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
Stade Toulousain 7.36 6.34 1.00
La Rochelle 6.93 6.88 0.10
Bordeaux Begles 5.23 5.27 -0.00
Racing 92 5.02 4.86 0.20
Toulon 3.84 4.09 -0.30
Lyon 3.44 3.10 0.30
Stade Francais 2.76 -1.05 3.80
Montpellier 2.67 4.18 -1.50
Clermont 2.03 4.05 -2.00
Castres Olympique 0.04 2.87 -2.80
Section Paloise -0.21 -2.12 1.90
Aviron Bayonnais -1.41 -4.26 2.80
USA Perpignan -3.60 -2.75 -0.90
Brive -6.85 -4.20 -2.70

 

Performance So Far

So far there have been 184 matches played, 132 of which were correctly predicted, a success rate of 71.7%.
Here are the predictions for last week’s games.

Game Date Score Prediction Correct
1 Stade Francais vs. Racing 92 Jun 03 20 – 33 5.40 FALSE
2 Lyon vs. Bordeaux Begles Jun 05 25 – 32 5.60 FALSE

 

Predictions for the Semi-finals

Here are the predictions for the Semi-finals. 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 Stade Toulousain vs. Racing 92 Jun 10 Stade Toulousain 2.30
2 La Rochelle vs. Bordeaux Begles Jun 11 La Rochelle 1.70

 

Super Rugby Predictions for the Quarter-finals

Team Ratings for the Quarter-finals

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 17.01 17.95 -0.90
Chiefs 13.48 8.81 4.70
Blues 12.81 12.34 0.50
Hurricanes 10.19 9.59 0.60
Brumbies 6.35 6.64 -0.30
Highlanders 1.30 5.04 -3.70
Reds -0.51 1.89 -2.40
Waratahs -1.68 -2.50 0.80
Rebels -4.61 -6.19 1.60
Western Force -6.15 -5.54 -0.60
Fijian Drua -8.77 -10.50 1.70
Moana Pasifika -10.80 -8.91 -1.90

 

Performance So Far

So far there have been 84 matches played, 64 of which were correctly predicted, a success rate of 76.2%.
Here are the predictions for last week’s games.

Game Date Score Prediction Correct
1 Blues vs. Highlanders Jun 02 16 – 9 15.80 TRUE
2 Brumbies vs. Rebels Jun 02 33 – 17 14.20 TRUE
3 Fijian Drua vs. Reds Jun 03 41 – 17 -6.90 FALSE
4 Hurricanes vs. Crusaders Jun 03 27 – 26 -3.80 FALSE
5 Waratahs vs. Moana Pasifika Jun 03 24 – 33 16.50 FALSE
6 Western Force vs. Chiefs Jun 04 19 – 43 -13.20 TRUE

 

Predictions for the Quarter-finals

Here are the predictions for the Quarter-finals. 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. Waratahs Jun 09 Blues 20.00
2 Chiefs vs. Reds Jun 10 Chiefs 19.50
3 Crusaders vs. Fijian Drua Jun 10 Crusaders 31.30
4 Brumbies vs. Hurricanes Jun 10 Brumbies 1.70

 

Currie Cup 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
Cheetahs 4.40 4.67 -0.30
Sharks 4.06 -1.30 5.40
Pumas 2.80 2.84 -0.00
Bulls 1.29 3.43 -2.10
Griquas -1.46 1.39 -2.90
Western Province -1.96 -3.24 1.30
Lions -2.64 -7.79 5.20
Griffons -16.50 -10.00 -6.50

 

Performance So Far

So far there have been 52 matches played, 31 of which were correctly predicted, a success rate of 59.6%.
Here are the predictions for last week’s games.

Game Date Score Prediction Correct
1 Griquas vs. Western Province Jun 03 38 – 29 3.70 TRUE
2 Bulls vs. Griffons Jun 03 64 – 33 20.30 TRUE
3 Pumas vs. Cheetahs Jun 04 14 – 29 5.10 FALSE
4 Sharks vs. Lions Jun 04 29 – 21 11.20 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 Griquas vs. Pumas Jun 09 Pumas -0.30
2 Lions vs. Griffons Jun 10 Lions 17.90
3 Bulls vs. Cheetahs Jun 11 Bulls 0.90
4 Western Province vs. Sharks Jun 11 Sharks -2.00