Cause and Effect

I wrote yesterday about the difference between correlation and cause. Today I came across this article on a study that shows a correlation between rainfall and autism. Apparently, there are higher levels of autism in rainy counties. So does rain cause autism? Here are a some unanswered questions that can give you an idea of the problem with studies like this:

1. Do people in rainy counties drink more?
2. Do people in rainy counties smoke more? Do more drugs? Take more anti-depressants?
3. Do they have children earlier in life or later in life?
4. Do they eat more meat?
5. What's the difference in levels of autism? Is it really statistically significant.
6. Do the same correlations exist in other parts of the world?

Information like this is less than useful.