… according to the 2013 Census figures,
- 51 would be female, 49 male.
- 70 would be European, 14 Maori and 11 Asian.
- 24 would have been born overseas
- 21 would have a tertiary qualification
- 4 would be unemployed.
- 4 would earn over $100,000
… according to the 2013 Census figures,
The anti-fluoride Fluoride Action Network has accused the Waikato Times of reversing the results of an online poll that asked whether people supported the council’s move to defer re-fluoridating the city’s water supply until a High Court legal challenge is decided.
What the Waikato Times did or didn’t do is immaterial. Folks, the paper ran a self-selecting online poll, which makes its results utterly meaningless.
The best poll we have on this is October’s non-binding referendum. It showed that nearly 70% of Hamilton voters favoured water fluoridation.
Bogus polls are only useful for advertising, but as long as they are honest about it, that’s not a problem.
As a meritorious example, consider Forest & Bird’s Bird of the Year poll, which starts today. It exists to raise awareness of NZ birds and to get stories in the media about them, but it’s not claiming to be anything else.
At the time of writing, the kereru, ruru, and albatross were tied for first place. They’ve got more security to prevent multiple voting than the newspapers do — you can only vote once per email address — but it’s still just a self-selected poll of a tiny fraction of the population.
Radio NZ science broadcaster Allison Ballance is lobbying for the albatross, which is an excellent choice, but the only official StatsChat advice is to watch out for the penguins.
A recurring point on StatsChat is that single election polls don’t have a large enough sample size to track short-term changes in opinion. Some form of averaging is necessary.
The excuse for pointing this out again is the Herald-Digipoll result with an increase of 6.8% since the previous poll in June. Since the poll has a 3.6% margin of error for a single estimate, its margin of error for changes is about 5%, so 6.8% is quite impressive.
On the other hand, Danyl Mclauchlan just tweeted a nice interactive plot of aggregrated poll results. I can’t embed it because WordPress is scared of SVG graphics, but the key chunk is here and you can click for the interactive plot
The highlighted points are past Herald-DigiPoll results, and there is indeed a big jump since June, but there’s almost no change since March. This poll seems to have given more variable results for Labour than the other polls do.
The conclusion: it’s too early to tell whether the change of management at Labour has affected opinion. But it’s probably more than a year until the election. We can wait a few weeks for the polls.
[Update: I'm apparently wrong about the excess variability in the Labour results, according to Peter Green on Twitter. Statisticians can overinterpret numbers just as much as the next guy]
[Further update: Twittering establishes that all the obvious suggestions for potentially-better ways to smooth the data have been tried.]
The Critic, the student magazine of Otago, has an interesting feature on the council elections, rating the candidates on six issues determined by polling to be important to students. One of the ways they present the candidate ratings is with radar plots
These show the rating for each of the issues on six radial axes, connected to form the white polygon. Candidates who are more ‘student-friendly’ on these issues will end up with larger polygons, and the different shapes show that there are significant tradeoffs between, say, a candidate who is in favour of drinking and (quality) loud music, and one who is sound on environment and transport.
This is a pretty good use of radar plots. Their main limitations are that the ordering of the axes can have a big effect on the visual impression, and that evaluating tradeoffs quantitatively is hard. Neither is a really serious limitation here, and both are problems common to many ways of displaying multivariate data.
Here’s another radar chart, originally from INFOGRAPHIKA magazine, rescued from its unfair banishment to wtfviz.net.
This one shows how people rated the importance of eight factors in success, split up by their income. It’s interesting to see how much higher connections, initial capital, and cheating were rated as important by the poor, and how the rich thought hard work was the key factor, not being very impressed even by education. It’s clear that each group likes the story that makes them look good; less clear who is more correct. What’s a bit depressing is how small a role anyone thinks is played by luck.
Today is the 120th anniversary of women’s suffrage in New Zealand, with commemorations in a range of places, including the Centenary fountain in Khartoum Place, Auckland
The petition for women’s suffrage, signed by about 24000 women, was submitted to Parliament in July 1893
and the names of the petitioners have been digitised and made available at New Zealand History Online.
I haven’t been able to work out exactly what the adult female population of NZ was at the time, but the digital yearbook says that there were 305287 non-Maori females, that 30.94% were married and 4.11% widowed, and that there were 67000 never-married females 15 and older. Depending on how many of the never-married 15+ were 21 or older, this gives perhaps 150000, so about 16% of the non-Maori adult female population signed the petition. That compares to modern petitions with about 2.4% of voting-age people opposing marriage equality and about 10% for the anti-asset-sales petition (though these are targeting the entire NZ voting population, not just women).
Presumably, rather more than 16% of women were in favour of getting the right to vote, but it’s always difficult to track people down and get them all to sign. In 1893 there wasn’t an alternative: sampling hadn’t been invented, and would likely have been impractical – certainly, calling random phone numbers wouldn’t have got you very far.
Today, we have much more accurate ways of estimating the proportion of people who support some government action. Petitions, like demonstrations, are mostly useful for signalling to the government that some issue they weren’t aware of is actually important. For example, the petition against animal testing for legal highs would have been effective to the extent that the government wasn’t aware people cared about the issue. For anyone who was aware this was a political issue, a well-conducted opinion poll would be more informative and should be both less expensive and more effective than a petition.
Referendum petitions, as in New Zealand and some parts of the US, are an example of this principle: if an issue can get the support of 10% of the NZ voting population, it’s probably important enough to be worth serious consideration and debate. The threshold is weaker in many places. For example, in California a petition need only get 5% of the number of people who voted in the last election for state governor, which currently comes to under 2% of the adult population.
The Dominion Post has a story (via @LewSOS) on the Wellington mayoral elections.
John Morrison is leading incumbent Celia Wade-Brown in the race for the Wellington mayoralty, according to a poll of Dominion Post readers.
Mr Morrison, who has been a city councillor for the past 15 years, had support from 27 per cent of the 635 readers surveyed last week – while Ms Wade-Brown trails on 17 per cent.
They don’t say how the survey was done — it’s not clear how you would get a representative sample of Dominion Post readers. For all we can tell, it might just be a bogus poll. It’s also not clear, on this topic, why Dominion Post readers are even the population you would want, since the story continues
Of those surveyed, 275 were eligible to vote in the Wellington City Council elections.
You’d at least expect that the voting preferences would be broken out by eligibility.
Uh-huh. Lonergan’s own national poll reports only a 2 per cent swing against Labor. Yet in the three seats it polled individually, it found an average swing of 10 per cent. That’s huge, far bigger than we have seen in any Federal election since 1943.
and I was similarly dubious.
We now have the facts: the national (two-party preferred) swing against Labour is just over 3%, and the swing in Kevin Rudd’s seat of Griffith, one of the three specifically polled and predicted to have a swing of 10.5%, was 5.42%. The other two seats mentioned in the story as polled by Lonergan were Forde (robopoll swing 8.5%, actual swing 2.5%) and Lindsay (robopoll swing 11%, voters 3.9%)
It looks as though the robopoll skeptics were right. Even though the national swing was larger than the poll predicted, the swings in the target electorates were much smaller.
Australia, as you may have noticed, is having an election. Some statistical analysis links
Two episodes to be noted
First, the GCSB bill.
We’ve had a nomination for Stat of the Week for the Campbell Live bogus poll finding 89% opposition to the bill: you just can’t draw that sort of conclusion from self-selected phone-in polls. On the other hand, they did get over 50000 identified individuals voting, so as a petition it isn’t completely negligible — that’s a bit more than 1.5% of voters.
The Fairfax/Ipsos real poll found a bare majority who trusted the government to protect privacy and only about 30% who were seriously opposed to the bill. The pollster or the papers fell down badly by not giving us a party breakdown of these figures. If half the 30% were National voters, the government should have been concerned, but if, like me, they were mostly Labour/Greens voters already, there isn’t any political problem in ignoring them. It’s also a pity there wasn’t any polling relevant to the most obvious pressure point in the coalition – “Would you vote for ACT if they voted against the bill?” would have been an interesting and important thing to know.
Second, the West Island.
As you may have heard, they are having an election soon. In addition to the traditional election polls there are new automated ‘robopolls’ that are sufficiently cheaper that it’s possible to get a useful sample size in single electorates. Or perhaps not. The Sydney Morning Herald has an interesting report
Lonergan’s own national poll reports only a 2 per cent swing against Labor. Yet in the three seats it polled individually, it found an average swing of 10 per cent. That’s huge, far bigger than we have seen in any Federal election since 1943.