Sociology of numbers
Jul 30, 2009
I picked up a copy of AM New York (free newspaper given out in the subway stations) yesterday morning. So we are told: tanning beds are killers. See here for example.
How bad?
The article began:
The report found that the risk of skin cancer jumped by 75 percent when tanners started regularly using the beds before the age of 30.
A few paragraphs later, an "occasional tanning bed user" made a confession:
What?
What started out as a relative increase in risk of 75 percent (those using tanning beds compared to those who don't) ended up as a 3 in 4 chance of getting cancer!
This reminds me of Joel Best's books
in which he explored how data gets "adulterated" as it moves through society. I find his perspective fascinating and his books well worth a read. They are not your typical statistics book for sure.
I good example of why relative risks are a terrible way to communicate. I suspect they get used because they tend to make exciting headlines.
Gerd Gigerenzer has a great article on the BMJ website on communicating risk: http://www.bmj.com/cgi/content/extract/327/7417/741
Posted by: Stephen Hampshire | Jul 30, 2009 at 05:39 AM
Of course, the "deadly as taking arsenic" comment is just as ridiculous. Depending on how much arsenic you take, the risk of death from taking arsenic varies continuously from 0 to 100%, so one can add this comment to any article about something that that has any risk at all.
I notice that the article also doesn't consider the possibility that the increased vitamin D production might outweight the risk of cancer. Of course, there's a long history of people who ought to know better warning about the risk of sun exposure without mention vitamin D, which verges on being criminally irresponsible.
Posted by: Radford Neal | Jul 31, 2009 at 02:44 PM