Re-analysis of Cohen's ecologic radon study

["Dr Christoph Hofmeyr" <chofmeyr@nnr.co.za>]

Prof Cohen, Radsafers,

1. I read with interest that Wes van Pelt claims that a hidden variable has been found.  I have previously tried to point out that the inverse relationship of lung cancer deaths vs average radon concentration is rather dubious at the higher end of average radon concentrations cited by Cohen for 1601 counties.  I used a plot of county radon concentration Rank (i.e., Cohen's radon concentration ordered from smallest to largest), which exhibits a rather sharp increase of average concentration vs Rank towards the high end (it more than doubles between rank 1400 and 1600 from 3 to 6.4 pCi/l), but the trend of cancer data (male & female) plotted against radon Rank is effectively flat in that region.  With this plot one would expect any dependence to stand out 'like a sore thumb' in that region.  My interpretation is that here is no discernible dependence (no sore thumb) between radon concentration and lung cancer death at the 'high' end (upper half in terms of Rn concentration) of

 Cohen's data.  To me the main thrust of 'Cohen's paradox' is clearly below 3 pCi/l.  This is the first point. 

2.  The second point has only recently occurred to me.  The 'best fit' trend of Lung Cancer against radon Rank plot is a linear negative slope over all 1601counties for males as well as females,  of course, qualified by the spread in data.  For males the average goes from approximately 70 at Rank 1 to approximately 50 at Rank 1500, for females from approximately 14.5 at Rank 1 to 9.5 at Rank 1600.  The fact that males are almost 5 times more likely (on average) to die from lung cancer over the whole range is a clear indication that radon concentration is probably irrelevant as a cause in the range considered.  If I'm not mistaken, the very similar male and female 'shape of the dependence'  despite a 5:1 ratio on an absolute scale seems to preclude radon as a cause. Nowhere in RP is such gender inequality in terms of ionising radiation contemplated (gender-defining organs possibly excepted).  Own thoughts.

Chris Hofmeyr <mailto:Hofmeyr@nnr.co.za> 

chofmeyr@nnr.co.za