>"The usual strategy is to control for smoking. If nuclear test rate correlates with lung cancer rate, but does not correlate with non-smoker lung cancer rate, nuclear test is not causing lung cancer."

I'm not really concerned with whether there is, or is not, a correlation, I already know there is a correlation.

I am concerned about: How much of the increase in lung cancer incidence we see in the data could be accounted for via exposure to radiation from nuclear tests? I doubt it is zero, but it could be relatively negligible I suppose.

The timing of it does overlap quite well though.