Smoking Ban Means Non-Smokers Suffer Less Heart Attacks
DIZZY notes a dodgy correlation with smoking statistics.
What is it these day with people mistaking statistical correlation with causality? I fully understand it can make something that sounds like an appealing finding, but honestly, sometimes it’s just silly. Take for instance this litte piece in this morning’s Times with the headline “Non-smokers suffer fewer heart attacks after ban”. It goes on to say,
The number of nonsmokers admitted to hospital after heart attacks fell by 20 per cent in the ten months after the ban came into force in March 2006, compared with the same ten months in the year before, Jill Pell, of Glasgow University, said…. In the ten months of the year leading up to the ban, there were 3,235 admissions, while in the matching period after the ban, the figure was 2,684.
The general angle of the entire piece is that there the two fact when juxtaposed are somehow evidence of causality. Indeed, Jon Ayres, head of the University of Aberdeen environmental and occupational medicine department, is quoted as saying “This also suggests that the important thing was the smoking ban.” Actually it doesn’t at all.
All it suggests is less people had heart attacks. To draw conclusions of causality based on a single, and deliberately chosen catalyst based on nothing more than correlation with one previous year is entriely foolish. In fact, let’s flip this on its head for a second.
If the number of heart attacks amongst non-smokers had increased during the same time what would the reaction of these same people be to someone standing up and saying something like “Non-smokers suffer more heart attacks after smoking ban therefore the ban should be abolished”? You can bet you’re bottom dollar that they would deride such conclusions as dangerous statisical correlation masquerading as causality.
I imagine, if one had a dig around here, one could easily find that since the smoking ban the amount of effluent in Scottish rivers had changed too, but would they stand up and try to claim the two were linked on the basis of numbers alone?
Posted: 11th, September 2007 | In: Reviews Comment (1) | TrackBack | Permalink
