Space and time
Degrees of likeness 1

Sociology of numbers

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:

Using a tanning bed regularly is as deadly as taking arsenic, a shocking study to be published today says.
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:

"I always knew it wasn't good for your skin.  Definitely 75 percent risk of cancer is not that encouraging and not worth the risk."


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.



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Stephen Hampshire

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:

Radford Neal

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.

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