Iowa Controls - Not Matched

[hflong@postoffice.pacbell.net]

 Howard Long MD MPH, Family Doctor and Epidemiologist

 363 St. Mary St., Pleasanton CA, 94566

 (925) 846-4411, Fax 4524, Page 787-0253 hflong@pacbell.net



Dear Professor Field,



I have great respect for your scientific honor and the quality of the

Iowa study.

I am happy that you write, “I AM NOT A DEFENDER OF THE LNT THEORY”.



When opposite inferences are reasonable from similar studies, like your

Iowa study and the N Shipyard Worker Study (also case control and 10 x

as large as yours), I believe an experiment is needed.



First, even if a drug company were to fund 100 clinical trials,

(prospective and double blind) with N in each such that some trials

would likely show p<.05 of chance results,but publish only  studies

showing benefit, would it show the medicine effective?

You studied the one location in 100 (Iowa women) having no negative

correlation of radon and lung cancer mortality, in Cohen’s study - 200 x

as large, albeit ecologic.

 .

Second, in Topics Under Debate, Radiation Protection Dosimetry V95,1,p77

you write in Rebuttal, “The participants’ smoking histories do not need

to match the smoking histories of the controls since the effect of

smoking can be adjusted for using standard statistical methods.” This

follows Klaus Becker’s Argument that “- in the Iowa Lung Cancer Study by

Field et al 86% of the ling cancer cases were smokers, but only 32% of

the controls.” Ibid, p79. Our Professor of statistics at UCB PH, Bill

Gaffney, would often remind us,

“Know your assumptions!” In your study, the controls are not matched. I

do not believe that here, “smoking can be adjusted for using standard

statistical methods”.



I, unlike some cynical colleagues, believe that your intent, like mine,

is to prevent lung cancer and advance science. I have in the past

rationalized projects (like a method of colon cancer detection) more

than I believe you have rationalized this power of statistics to correct

for the difficulty in finding controls that match for smoking. I hope

you will come to believe, as I do, that less smoking by controls may

have been the reason they had less cancer, rather than the less radon.



With continued respect and best wishes



Howard Long