Difference between one number
StatsChat goes on and on about the need to compare numbers: if you have two polls of the same question, you should probably compute either an average or a difference.
It could be seen as positive, then, that the Herald is reporting changes in attitudes to Aucklanders, with the headline “Poll finds rest of NZ warming to Jafas”
A recent Herald on Sunday-commissioned poll found around 45 per cent believed Aucklanders held themselves in higher regard than other New Zealanders.
Unfortunately, if you just have one poll, as the Herald does, taking differences becomes more difficult. They have to fall back on an opinion (from a tourism manager at Ateed)
“If you had conducted a poll like that 15-20 years ago the numbers would have been a lot higher.
“Attitudes towards Auckland are changing and more people from outside Auckland are choosing to live here.”
Sounds plausible, and I assume he knows what he’s talking about, but it would have worked just as well without the poll.
Also, if you’re going to ask people about attitudes towards Aucklanders, who make up about 1/3 of the population, it really matters whether Aucklanders are included in the sample or not. At least, it would if the poll results mattered for the story. The Herald doesn’t say.
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 »