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Re: ecological fallacy and the LNT
Jim,
The concept of ecologic fallacy was described long before Dr. Cohen
performed his first ecologic study. It is ludicrous to state the ecologic
fallacy was created to discredit Dr. Cohen's ecologic fallacy. If this is
truly what you believe, how can your responses be considered credible?
Bill Field
----- Original Message -----
From: Jim Muckerheide <jmuckerheide@cnts.wpi.edu>
To: Field, R. William <bill-field@UIOWA.EDU>; <RuthWeiner@aol.com>;
<radsafe@list.vanderbilt.edu>
Sent: Sunday, February 17, 2002 1:40 PM
Subject: RE: ecological fallacy and the LNT
>
> From: Field, R. William [mailto:bill-field@UIOWA.EDU]
>
>
> Ruth,
>
> Ecologic fallacy is merely an inappropriate conclusion regarding
> relationships at the individual level based on ecological data (Kelsey
> et al. 1986).
>
> <Only sine the epi establishment committed itself to discredit Cohen's
> clear results to meet a bureaucratic-funding agenda.>
>
> However, ecologic studies inherently have many weaknesses that lead to
> an inappropriate conclusion. For example,
>
> 1) in case-control studies nondifferential (or random error) exposure
> misclassification usually causes bias toward the null. However, in an
> ecologic study nondifferential misclassification can drive either
> sizable under or over estimation of the exposure disease relationship.
>
> 2) Using summary measures (like sales tax to represent smoking
> prevalence) for a county is very inadequate to control for confounders.
>
> 3) Some factors that are not confounders at the individual level can be
> at the ecologic level. To have any hope of control for confounding at
> the county level, you need very detailed information on the confounding
> and exposure variable distributions within a county. That is why I
> previously suggested to Dr. Cohen that he try to obtain this information
> (method suggested by Guthrie).
>
> <All semantics. Nothing that can change Cohen's plain data.>
>
> 4) Jim Muckerheide often cites the large numbers of counties in Dr.
> Cohen's studies. But, the availability of large numbers does not
> eliminate biases no matter if you had an infinite number of counties.
> Large numbers do help improve the precision (narrow confidence bands),
> but the large numbers have no effect on reducing biases. In other
> words, the finding can be precisely wrong.
>
> <I don't say what you said I say :-) If there were a "bias" that is
> several times larger than smoking AND inversely correlated with radon
> exposure, you would be right. And Bernie would be right in agreeing with
> you. :-) Bernie says its "not plausible." I say it doesn't exist. There
> is only one plausible "bias." That is that radon improves the health of
> the lung, consistent with biological models, and reduces the incidence
> of lung cancer. Contrary "bias" does not, and can not, except in
> mathematical fiction, exist to change the results of every one of
> hundreds of independent studies of county-level data. But the "bias" of
> beneficial effects of radon exposure is a direct and unambiguous
> foundation for the results.>
>
> 5) I have seen no data from Dr. Cohen to show that the risk factors
> within counties are not correlated. Unless the risk factors are purely
> additive (and I see no evidence of that), the dose response findings for
> the ecologic study will be biased.
>
> <Semantic, fictional, not even "hypothetical," risk factors. As above
> actual "bias" doesn't exist at a level to substantially affect the
> results. Bernie may want to be "conservative" in interpreting his data,
> and limit the "test" to the whether the LNT can survive, but that
> doesn't change the results either. >
>
> Ruth, in your example below, the population is not at all defined so the
> concept of collective dose and collective risk can not be used.
> Collective dose and collective risk can only begin to be considered
> valid if the exposed population can be well described and quantified.
> For example, many groups of workers who may have a higher risk of
> exposure can be quantified by age, job description, sex, length of
> employment and a multitude of other factors. The general (working)
> group I described above has many more demographic details than is
> available in ecologic studies. If you don't have better demographics
> than are available in a county ecologic study, you likely should not be
> using the collective dose concept.
>
> <More nonapplicable semantics. Large worker studies show consistent
> results, except for cases like Steve Wing and IARC/Cardis who selects
> groups to report after finding which small subsets trend up (for
> whatever/any cancer) while the whole population and most cancers trend
> down, and ignore the fact that in the next study it's a different cancer
> that trends up while the first cancer and no "old group" or other
> subgroup, confirms the previous study - but like radon case-control
> studies, the data are too poor to have definitive results so the rad
> protectionists run around claiming "uncertainty, need more work (and by
> the way, keep pouring $100s Billions down the agency programs rat holes
> - into our pockets!">
>
> Pardon my short answer, but I am swamped with other work related demands
> right now.
>
> <Not too short, just not right :-) >
>
> <Regards, Jim>
>
>
> Best Regards, Bill
>
>
>
> At 09:45 AM 2/12/2002 -0500, RuthWeiner@AOL.COM wrote:
>
>
> Dear RADSAFERs
>
> I am working my way through both Field et al (and some ancillary
> papers kindly sent me by Dr. Field) and Dr. Cohen's papers (thatnk you,
> Bernie, for sending them). I am trying to understand the papers with
> all their nuances. I believe this can be done by a reasonably competent
> scientist like me (Ph. D. -- chemistry) without special training in
> epidemiology, but from time to time I will post questions -- real
> questions to which I would like real straightforward answers -- on
> RADSAFE. Let me say at the outset that these questions are not intended
> to castigate anybody or take sides. If I use the LNT in a question, it
> doesn't mean I endorse it. The questions are for information. (and
> if they sound repetitive to the individual who accused me of "me
> too-ism" well, that can't be helped). So here is my first question,
> about the "ecological fallacy."
>
> Let us say the cumulative dose to a population of 10,000 persons
> is 1000 PERSON-rem. Then, according to the LNT, one might expect 0.5
> excess cancer in that population of 10,000 (0.0005*1000 = 0.5). One can
> also, independently, say that the average dose is 0.1 rem (1000/10,000 =
> 0.1), or 100 mrem. But to say that therefore the average expected
> cancer incidence would be 0.000005 (0.0005*0.1) is the fallacy in
> question. Essentially, "average individual cancer expectation" or
> whatever is meaningless. Have I got it right? If not,what is my
> mistake?
>
> (The LNT conversion from rem to cancer is from ICRP 90, page 22)
>
>
> Ruth Weiner, Ph. D.
> ruthweiner@aol.com
>
>
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