Re: "Accepting the limits of ecologic studies: Drs. Greenland and Robins reply to Drs. Piantadosi and Cohen".
Cohen
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BL
D000293:Adolescent; D000328:Adult; D000368:Aged; D015986:Confounding Factors, Epidemiologic; D004463:Ecology; D006801:Humans; D008175:Lung Neoplasms / Q000209:etiology*; D008297:Male; D008875:Middle Aged; D012907:Smoking / Q000009:adverse effects*