The Delphi method of forecasting is useful when:
◦ a systematic approach to creating and testing hypotheses is needed and the data are usually gathered by sending a questionnaire to consumers.
◦ historical data are available and the relationship between the factor to be forecast and other external or internal factors can be identified.
◦ historical data is available and the best basis for making projections is to use past demand patterns.
◦ judgment and opinion are the only bases for making informed projections.