Tuesday, March 6, 2007

Does Proximity to a Lake Cause People to Have Colonoscopies?

There is a weak, though statistically significant correlation between the two. Specifically, an increase in a state's area under water is associated with an increase in the percentage of people over the age of fifty who have colonoscopies.

Therefore, in order to encourage more people to have colonoscopies, we should increase the size of lakes -- or somehow submerge more land under water. Artificial flooding would probably do the trick -- or perhaps increased carbon emissions would lead to health-improving global-warming floods.

But then, maybe we have cause-and-effect reversed. Perhaps an increase in colonoscopies results in more land-under-water; colonoscopies might be a bigger threat to the environment than the aforementioned carbon emissions!

Or, could this all be coincidence? In fact, I went to
StateMaster, and arbitrarily selected the "Percentage of Area Water" statistics. Statemaster then spit out a long list of correlations with related (and seemingly unrelated) variables, and "Colonoscopy Testing" just happened to be on the top of the list.

No matter how often we hear "correlation is not causation", it never quite sinks in.

Maybe this should be called the "correlation-is-causation" bias.

Makes you think about the relationship between human activity and global warming, too.

1 comment:

Lexcen said...

My introductory course into statistics taught me that you can prove anything with statistics and correlation is the way to do it.