Consensus methods: a bridge between clinical reasoning and clinical research?

Evidence-Based Practice does head the "hierarchy of evidence" upon which developments in clinical practice should be based. There are, however, situations where evidence is either unavailable, unclear, or results between studies are at variance. Consensus is a reliable contingency, and approaches to reaching consensus have acceptable construct validity (Nominal Group Technique, Delphi, and Consensus Development Conference). Consensus is reached when: (i) the method of investigation tightly controls communication to reduce the obscuring "noise" of divergent discussion; (ii) statistical measures of agreement or dissent screen out the bias that would otherwise be produced by the dictate of vociferous minorities or coalitions that may represent vested interests; (iii) all participants contribute equally to the product of the investigation.