Etiologic study vis-à-vis intervention study.

Understanding of the logic-dictated essence of the etiologic study, and similarly that of the intervention-study, in the advancement of the knowledge-base of medicine, remains incomplete. Viewing experimental intervention-studies ('clinical trials') as paradigmatic for etiologic studies-necessarily non-experimental-has been wrongheaded. This misunderstanding continues to impede understanding of the essence of what logic dictates to be the etiologic study, adduced decades ago but still commonly confused with the essence of the (seriously malformed) 'case-control' study. Correct understanding of the essence of the etiologic study would pave the way to improved understanding of the intervention study, notably as to how prognostic probability functions could be derived from the data now routinely produced in clinical trials. This paradigm reversal, too, has been previously proposed, but its understanding has remained fogged by wanting understanding of the etiologic study.