The Delphi and nominal group techniques in health services research

This review examines two methodologies that are being increasingly used in health services research (HSR): the Delphi and nominal group techniques. The Delphi is a survey technique for decision making among isolated respondents while the nominal group technique (NGT) is a highly controlled small group process for the generation of ideas. Typical applications of the techniques are for the development of consensus guidelines or standards in areas where research based evidence is absent or inconclusive. We discuss methodological issues associated with these techniques, namely, sample size and composition, response rates, anonymity, feedback and consensus, and reliability and validity. We also illustrate tire range of applications of the techniques in HSR, including pharmacy practice. Although not widely used to date, both methodologies are potentially valuable additions to the practice researcher's toolbox.