Posts from May 2025 (28)

From RNZ this week

The Wedding Planner director Susannah Reid said in 2023 $58,000 was a typical budget for a wedding across New Zealand but this year, the average cost was more like $87,600.

As we’ve seen in the past, this use of ‘typical’ by people in the wedding industry doesn’t have a lot to do with how the word is normally used.  In that post, in 2014, the typical value from the marital-industrial complex was $30,000.  In 2025 dollars that’s about $40,000, so apparently the real cost of “typical” weddings has more than doubled over the time StatsChat has been running.

Radio NZ also have this week: How New Zealand couples saved on their wedding (and what they splurged on). The most expensive wedding here is less than a quarter of the “typical” budget; the others are less than 10%.

If you think about it, estimating the actual cost of a typical wedding is quite hard.  Technically it’s not that difficult: the government keeps track of marriages, so you could do a survey of a sample of marriages and ask people, but the Births, Deaths, and Marriages people will only let you browse arbitrary marriages from the distant past. Contemporary marriages are public records, but public access to them is by name rather than just by year.   If you don’t have a genuine sample, you’ll tend to notice big weddings more than small ones.

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.

Performance So Far

So far there have been 72 matches played, 51 of which were correctly predicted, a success rate of 70.8%.
Here are the predictions for last week’s games.

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.

Team Ratings for Round 13

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 93 matches played, 49 of which were correctly predicted, a success rate of 52.7%.
Here are the predictions for last week’s games.

Predictions for Round 13

Here are the predictions for Round 13. 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 13

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 98 matches played, 61 of which were correctly predicted, a success rate of 62.2%.
Here are the predictions for last week’s games.

Predictions for Week 13

Here are the predictions for Week 13. 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.

Newsroom has an article about tertiary funding in the new budget.  There’s a graph showing how the government fee cap and inflation have competed over the past few years. The graph in the article (ignoring the impact of a fee-free year) is

I find this a bit hard to interpret — it’s not easy to see the cumulative effect of the two changes and work out whether fees have shot ahead or lagged behind.  I think this is clearer, showing the cumulative effect of inflation and the (maximum) fee increase; the highlight is the two Covid border-closure years.

We can see that fees had increased in real terms but had now fallen behind inflation. Based (obviously) on a projection for 2026, fees might be slightly ahead again.

Another option is to use the inflation series to deflate the fee cap and just show the real-terms fee changes. Again, fees were up in real terms, then down, and are right at the 2014 level. Again, this ignores the impact of a fee-free year, which will depend on when one started uni.

What I think this shows is that adding up yearly changes (especially multiplicative ones) in your head is hard, and it’s probably harder than the opposite task of estimating changes in slopes.  If you need both scales, you might be better off with a cumulative graph.   The big disadvantage of a cumulative graph is that the visual impression can be quite sensitive to when you start adding.

RadioNZ have How many years would you have to skip coffee to save enough to buy a house?

The story correctly says (a) a lot, even if house prices didn’t go up, and (b) that’s not really the question.

There’s one point they miss  which is important to a lot of the narrative on house prices and saving (perhaps because this is a personal finance article, not a housing prices article).

The reason for housing unaffordability isn’t that Kiwis aren’t spending enough on housing.  You could imagine a world where housing was readily available and affordable, but people in general, or some group of people, couldn’t buy houses because they were spending all their money on beer and holidays and not saving anything for a deposit. In a world like that, advising people to save might be useful (if they listened).

That’s not the problem in New Zealand.  Kiwis, collectively, are spending far too much on housing. If one person gave up coffee or avocado toast  to save faster it might help them a little bit.  If we collectively gave up coffee and avocado toast to save faster, housing prices would just increase faster to compensate.

Q: Did you see golf courses cause Parkinson’s Disease?

A: Maybe?

Q: Pesticides. In groundwater.  We should close down the Auckland golf courses!

A: Possibly, but for other reasons.

Q: Aren’t the pesticides bad?

A: There are some pesticides with reasonable links to Parkinson’s Disease, in particular paraquat (actually a herbicide) and organophospates. Most of the evidence in humans comes from farm workers, who get exposed to quite a lot of the stuff

Q: So these could explain the golf courses?

A: They could, but there are other differences between the people with and without Parkinson’s in the study, not just golf courses

Q: Some dude on Twitter said the cases were all near the Mayo Clinic and the controls were from all over

A: That sort of thing, but in fact the research paper includes an analysis with controls just from the same county as the cases, and the results aren’t all that different. It could still be that that the cases lived nearer the medical center; we can’t tell.

Q: So doctors cause Parkinson’s Disease?

A: More the reverse.  The researchers did make sure the cases lived in the right county at the time of diagnosis, but family history can matter, and the cases had seen a doctor more often in previous five years than the controls.  Also, doctors do cause diagnosis of Parkinson’s disease, which is what was measured.

Q: But it might be real?

A: Plausibly, yes.

Q: What about Auckland, then?

A: We get our water mostly from the Waitakeres and the Hunua ranges, which are not topographically suited to golf courses.  And most of the groundwater used in New Zealand is deep enough to be relatively safe.  And NZ is a bit fussier about what herbicides and pesticides we allow.

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.

Performance So Far

So far there have been 144 matches played, 101 of which were correctly predicted, a success rate of 70.1%.
Here are the predictions for last week’s games.

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.

Team Ratings for Round 25

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 167 matches played, 126 of which were correctly predicted, a success rate of 75.4%.
Here are the predictions for last week’s games.

Predictions for Round 25

Here are the predictions for Round 25. 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 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.

Performance So Far

So far there have been 68 matches played, 48 of which were correctly predicted, a success rate of 70.6%.
Here are the predictions for last week’s games.

Predictions for Week 15

Here are the predictions for Week 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.