January 14, 2019
Reeferendum polling
The Herald reports 60 per cent support for legal cannabis – new poll. There’s going to be a lot of this over the next couple of years, so here are some points to consider
- As the Herald says, the poll found a substantially higher number of daily cannabis users than other research: about three times higher than the NZ Drug Use Survey from the Ministry of Health and four or five times higher than a 2010 survey sponsored by NORML. This has got to reduce our confidence in the results: either because it indicates the sample is unrepresentative or because it indicates that surveys on drugs are intrinsically unreliable.
- We don’t know what the question on the referendum will be, so the survey obviously wasn’t asking that question. I hope the actual question will be a choice between a specific proposed set of legislation and the status quo, though the Government will have to move quickly to get the legislation drafted, released for public comment, and revised in time. In any case, you’d expect (as with Brexit) more support for a generic ‘change’ proposal as in this survey than for any concrete and specific proposal. Some people will support private growing but oppose commercialisation; others will argue that you can only get rid of the illegal market if the legal market is fairly open. And so on.
- The poll results were weighted to agree demographically with the 2013 Census population. That’s a standard thing to do with surveys, but in this case it would be more useful to weight them to look like the 2017 voting population. The age groups who support legalisation more strongly are also historically less likely to vote.
Thomas Lumley (@tslumley) is Professor of Biostatistics at the University of Auckland. His research interests include semiparametric models, survey sampling, statistical computing, foundations of statistics, and whatever methodological problems his medical collaborators come up with. He also blogs at Biased and Inefficient See all posts by Thomas Lumley »
I would suggest drug users are more likely to vote when the vote is about making cannabis legal then when it’s for a general election so I don’t think weighting it to the voting population would be a good thing. It would be useful as a sensitivity analysis.
A single drug survey is not that reliable because people whose drug use/dealing would come at a high cost if their information was somehow released to the police aren’t that truthful. But comparing two surveys is useful (if you assume no changes in people disclosing) because it says if things are getting better or worse and that’s useful if the point is to create or analyse policy decisions around population health.
5 years ago
Its not really a standard poll either, a similar ‘survey’ by Horizon Research
on ‘medical cannabis’ was done early December
Their method isnt to randomly call people and then ask questions like other polls, but to have an online survey panel of respondents who they ‘invite’ by email to take the current survey by computer. Emails are sent which offer prizes for participating- Win win win – that sort of thing.
”
Win this iPad Pro and $1000 cash in December!
An East Coast Bays retiree has won our September 30, 2018, major prize draw!
Aucklander Elizabeth W joined our HorizonPoll panel in April, 2017. She wins $2199 in cash!
“14 Nov 18 – We offered a $100 instant cash draw by midnight to complete one of our September surveys. …”
ipad pro ? Wonder what the December survey would ask with that as the teaser
Not only that but the ‘trophy question’ is in the email as a teaser.
The interesting part is the medical cannabis survey over 2000 online respondents – that was the Ipad Pro teaser , while the previous months survey had ‘around 1000’ – thats was ‘binding referendum on medical aid in dying”
I bet there wasnt a ipad pro to particpate online in that one.
I cant see an Horizon Survey done for the general election where we could see what the results were in comparison with the ‘ransom sample ‘ method. But Im not surprised at all that Helius Therapeutic, the cannabis business would find Horizon as the one to do a paid for survey.
5 years ago