Comparative effectiveness is the common denominator in health services research: experimental effects are promising,...

Sir Archibald Cochrane and Sir Austin Bradford Hill requested 80 years ago answers to three questions (Can it work? Does it work? Is it worth it?) before a new intervention is implemented in day-to-day healthcare. A critical analysis of currently accepted answers identified a terminology conflict that inherits the risk of misleading interpretations and inappropriate decisions.

For detection of the terminology problem and the development of the solutions was possible through three recommendations (the "Ulm heritage"): (1) Albert Einstein (*1879 in Ulm/Germany) predicted, "A problem cannot be solved with the way of thinking that caused it"; (2) The "hochschule für gestaltung ulm (Academy of Design, 1953-1968)" disseminated the rules of American designers and architects e.g., "Form Follows Function"; and (3) requested to "design not only individual but universally valid solutions with socio-political relevance".

Our data confirms the power of the FFF rule, the pros and cons of value judgments, the complexity of healthcare decisions, the difference between scientific statements and political decisions, and the effects of interprofessional collaboration.

"Efficacy" offers promising "Proofs of Principle (PoP)" while "effectiveness" describes "Real-World Effectiveness (RWE)". That is why the results obtained are always more important than hypotheses.