Denominators (when cellphones attack)
A question that is very unlikely to be interesting: were there more cellphone-related injuries in Dunedin or Auckland last year?
Auckland has a lot more people. Of course it has more cellphone-related injuries.
A question that is moderately unlikely to be interesting, but, ok, you might need to write a story: were people in Auckland more likely to have cellphone-related injuries than people in Dunedin?
So, where the Herald website (and presumably the ODT originally) has
In the three years to the end of 2016, ACC received 23 claims for cellphone injuries from Dunedin people and paid claimants a total of $10,436…
Statistics provided by ACC show Aucklanders made the highest number of claims at 190, costing a total of $76,159
the second paragraph might be better as
Although Auckland has more than ten times as many people, the home of the Vodafone Warriors had only 190 claims, costing a total of $76,159
(Someone who can actually write might do better than me here. )
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 »
Just two small observations:
Firstly, the ACC compensations are quite close across the country. By just considering the mean payout from these numbers, Dunedin (23) averages at $453/person, Auckland (190) at $400/person, and Queenstown-Lakes (3) at $367/person. Given small sample sizes for Dunedin and Queenstown, I can’t say we’re seeing regional bias in the amounts paid out.
Secondly, taking it a little further (seriously journalists, it’s a minute with a calculator), what’s the rate of injury per person (maybe per 10k people for useful numbers). Using the 2015 census stats, Dunedin has 117,300 people, so 1.96 cellphone injuries per 10,000 people. In contrast, Auckland has 1,453,800, giving 1.3 cellphone injuries per 10,000 people.
The bad statistician in me hence states with minimal certainty that you’re about 50% more likely to injure yourself in a cellphone-related injury in Dunedin, but at least you’d get an extra $50.
7 years ago
I think there also has to be consideration of the age structure of the two populations. Auckland being a drawcard for immigrants and young people looking for work or study is likely to have a younger population – and I would guess that younger people are more likely to own a cellphone and also spend more time using it. Therefore, if random cell-phone injuries happen, it would be more likely to happen to them.
An older person is more likely to need more treatment for the same injury compared to a younger person. So if Dunedin has an older population then that would explain the cost difference.
But probably the bigger thing for me, as a statistician, is that we don’t have any indication of the year to year variation so maybe the difference is meaningless.
7 years ago
The year-to-year variation should be roughly Poisson, at least as a first approximation — counts of independent rare events.
7 years ago
Does a cracked screen count as a cellphone injury?
7 years ago