Re: Confounders and Coincidences

["Tony Harrison" <Tony.Harrison@state.co.us>]

>>> "Jerry Cohen" <jjcohen@PRODIGY.NET> 05/04/03 11:46PM >>>



    In any case, as was discussed in previous messages on radsafe, all

epidemiologic studies up to and including those relating smoking to

lung cancer could be discounted on the basis of possible unknown

confounding factors or just plain coincidence.



Not "epidemiologic" studies, "ecological" studies.





> A few years ago Bernie Cohen and I were invited to attend a

committee

> hearing on LNT at the NCRP headquarters in Bethesda. At that meeting,

we

> watched as Jay Lubin derived on the board the mathematical

relationships

> associated with possible slope observations in an ecological study

such as

> Bernie's and showed convincingly that unrecognized and possibly

> undetectable cross-interactions between the variables could result in

a

> completely meaningless "observed" regression slope irrespective of

the

> underlying true relationship. Hence, it is a mathematical truth (not

a

> religious conviction) that the "observed" slope in Bernie's study of

the

> possible relationship for radon-induced lung cancer could be totally

> spurious. On the other hand, this is not a proof that it is

necessarily

wrong.





Tony Harrison, MSPH

Colorado Dept. of Public Health & Environment

Laboratory and Radiation Services Division

(303)692-3046

tony.harrison@state.co.us



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