The Delphi Technique : A Re-Evaluation of Research and Theory

This paper examines the Delphi technique critically to determine whether it succeeds in alleviating the 'process loss' typical of interacting groups. After briefly reviewing the technique, we go on to consider problems with Delphi from two perspectives. First, we examine methodological and technical difficulties, and the problems these have brought about in experimental applications. We suggest that important differences exist between the typical laboratory Delphi and the original concept of Delphi. These differences, reflecting a lack of control of important group characteristics/factors (such as the relative level of panellist expertise), make comparisons between Delphi studies unrealistic, as are generalizations from laboratory studies to the ideal of Delphi. This conclusion diminishes the power of those former Delphi critiques which have largely dismissed the procedure because of the variability of laboratory study results (e.g. Sackman (45)). Second, having noted the limited usefulness of the majority of studies for answering questions on the effectiveness of Delphi, we go on to look at the technique from a theoretical/mechanical perspective. That is, by drawing upon ideas/findings from other areas of research (e.g. Hogarth (27)), we attempt to discern whether the structure of the Delphi procedure itself might reasonably be expected to function as intended. We conclude that inadequacies in the nature of feedback typically supplied in applications of Delphi tend to ensure that any small gains in the resolution of 'process loss' are offset by the removal of any opportunity for group 'process gain'. Some solutions to this dilemma are advocated, which are based on an analysis of the process of judgment change within groups and a consideration of factors which increase the validity of statistical/nominal groups over their constituent individual components