Evidence on the relative accuracy of group methods

Andreas Graefe and Scott Armstrong report on results from an experiment on the relative accuracy of three structured approaches compared to traditional face-to-face meetings. The four methods were compared on a quantitative judgment task that did not…

Andreas Graefe and Scott Armstrong report on results from an experiment on the relative accuracy of three structured approaches compared to traditional face-to-face meetings. The four methods were compared on a quantitative judgment task that did not involve widely dispersed information among participants. Overall, Delphi performed best, followed by nominal groups, prediction markets and unstructured meetings. Of the three structured approaches, only Delphi outperformed a simple average of participants' prior individual estimates. The authors also report participant's ratings of the group methods. Participants preferred personal interaction such as in meetings and nominal groups. Prediction markets were rated least favorable. The pre-print version of the paper, which will be published by the International Journal of Forecasting, is available here (http://www.andreas-graefe.org/images/articles/graefe_armstrong_GDM_methods.pdf).

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