Re: Confounders and Coincidences

["Otto G. Raabe" <ograabe@UCDAVIS.EDU>]

May 5, 2003

Davis, CA



Dear Jerry:



I agree with you for the most part, but unknown confounders are not the

problem in epidemiological studies that they are in ecological studies. I

cannot agree with your blanket statement that "...all epidemiologic studies

up to and including those relating smoking to

lung cancer could be discounted on the basis of possible unknown

confounding factors...." The key difference is that the exposure of each

individual in an epidemiological study is evaluated and the statistical

probability of erroneous results is also evaluated. In an ecological study

we have no way of knowing the dose to any particular person, nor do we know

the chance that the results are spurious even if they are not. 



Sincerely,



Otto



**********************************************

Prof. Otto G. Raabe, Ph.D., CHP

Center for Health & the Environment

(Street Address: Bldg. 3792, Old Davis Road) 

University of California, Davis, CA 95616

E-Mail: ograabe@ucdavis.edu

Phone: (530) 752-7754   FAX: (530) 758-6140

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