Unfaithful to the data, too.
When I were young, the Serious News Outlets probably wouldn’t have admitted the existence of extra-marital affairs by non-celebrities, let alone written an article that’s basically advertising from an infidelity website press release.
In some ways the data are better-quality than most advertorials, because the website has complete data on its NZ members. They have even gone as far as using population sizes for NZ cities to estimate their, um, market penetration, which varied across the five main cities by as much as 0.06%. No, that doesn’t exceed the margin of error.
The Herald’s article starts off
If your partner supports National, has a PC, drinks Coke, eats meat, has a tattoo, smokes and is a Christian, be warned – they could be a cheater.
Leaving aside the gaping logical chasm in identifying website members as representative of all ‘cheaters’, what the data actually say is that more members support National, not that more National supporters are members. As you may recall, we determined not so long ago that more New Zealanders of all descriptions support National than any other party, so that’s what you would expect for members of the website. The proportion of National supporters in the election was 47%, among website members it’s 33%, so National supporters are substantially less likely to be members of the website than supporters of other parties. The proportion identifying as Christian among website members is very similar to the proportion in the 2006 census. 79% of website users are on PC (vs Mac). Again that’s a lower proportion of PCs than in the population of NZ computers (the Herald said 10% were Macs in July 2010, and for Aus+NZ combined, IDC now says 15%) but one explanation is that Macs have more of the home market than the business market. More members drinking Coke vs Pepsi is also not surprising — I couldn’t find population figures, but Coke dominates the NZ cola market.
The story doesn’t say, but we can also be pretty confident that the website members are more likely to be Pakeha than Maori, more likely to be accountants than statisticians, and more likely to have a pet cat than a pet camel.
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 »