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closecorrelation is not proof of causation
Posted by dgrant on 04 Feb 2009 at 21:28 GMT
The authors show a correlation of CD with refrigerated/frozen foods. But they also show a correlation with other items reflecting "the hygiene and comfort at home". An equally logical conclusion might be that CD is correlated with being exposed to domestic electricity rather than with one or more things that use electricity.
RE: correlation is not proof of causation
Hugot replied to dgrant on 12 Feb 2009 at 11:28 GMT
We do agree that correlation is not proof of causation and this is clearly stated in the paper and in the abstract.
Because we wanted to know if the cold chain hypothesis is plausible, we focused on refrigeration. However, it is true that many co-factors associated with refrigeration (and we have tested some in this study) can also be seen as relevant candidate environmental risk factors. Among them, electricity is logically acceptable but it is difficult to biologically understand how it drives Crohn's Disease per se.