Monday, October 26, 2009

Innumeracy

Something that bugs the hell out of me is when people look at a certain statistic and then make incorrect claims about what that statistic says.  Take the following:

A year into the study, 56 percent of those using chemotherapy were still alive, compared with only 16 percent of those who chose the enzyme therapy. In other words, those who picked chemo over the alternative treatment lived three times as long.

The author extrapolates that because the survival rate of the chemo group after 1 year is more than three times the survival rate of the non-chemo group, then the chemo group has lived 3 times as long as the non-chemo group.

 

That is simply incorrect logic.

 

What the study findings show is that the chemo group had three times the survival rate as the non-chemo group after 1 year.  Those are two very different findings.

What the author suggests is that after one year, the chemo group has lived for three years, or will live for three years, versus the non-chemo group (that’s what “three times as long” means).

 

I’m not a big fan of enzyme therapy, but that’s beside the point.  What REALLY bugs me is telling people that under treatment – x, you’ll live longer when the facts don’t bear that out to be true.

What IS true, according to the study, is that given a certain amount of time, you can triple your chances of survival if you choose treatment A versus treatment B.

 

But given enough time, your survival rate will eventually decline to zero.

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