This term was coined by the author in the course of researching and writing the book Sorry, wrong number! The allusion is, of course, to the mythical stratagem whereby the Greeks infiltrated the city of Troy inside a giant wooden horse. The Trojan Number is thus one of several stratagems by which authors get their articles or propaganda into the media.
The major form of Trojan Number is the size of study. Early on in the piece it will be mentioned that (to invent some arbitrary numbers) there were 60,000 people in the study. The number experiencing the condition in question, say toe-nail cancer, is, however, much smaller, perhaps 60. Of these the number indulging in the putative cause, say passive drinking, is even smaller say 20. There is a number expected (as a proportion of the 60) at random from knowledge of the statistics for the general population, say, 14. Thus the number that really matters, the excess number of cases, is half a dozen. It is surprising how often an apparently huge study whittles down to an excess that you can count on your fingers. If the number 6 had been mentioned at the outset, the claim would have been laughed out of court, so it is never mentioned, though you can often have a pretty good stab at deducing it. In the statistics of rare events and excess of 6 on an expectation of 14 would be unsurprising. The rest of the 60,000 are mere bystanders. Furthermore, though it is not always admitted, these studies are often part of a large data dredge, in which many combinations of condition and potential cause are covered, so that the inevitable coincidental excesses can be identified and claimed as significant.
There are other forms of Trojan Number. A favourite is the recycler. Some new statistic is presented, say 63.21% of passive drinkers are depressed. That gives you the headline and a couple of sentences. The rest of the article is then exactly the same as the one you read last month with the same propaganda (and the month before that and the month before……). This way the zealots get their invented numbers drummed into the popular conscience or academics get a bit more glory via the institution’s public relations office.
A variation on the recycler is the ignorance statistic – 72.45% of women under 35 are unaware that passive drinking causes toe-nail cancer – followed, of course, by the same old propaganda. And so on.....
One of the most effective forms of Trojan Number is the Virtual Body Count. Sub-editors cannot resist a headline Thousands to die of X. The most egregious example is the EPA's "meta-analysis" of Environmental Tobacco Smoke, which proclaims 3,000 US deaths from passive smoking. If you cut through all the statistical frauds, the results actually demonstrate that passive smoking is harmless.
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