The Delphi method was originally developed as a structured approach for collecting opinions about the future and judging the likelihood of future events or situations. In health technology assessment (HTA) and economic evaluation this method has been adapted (sometimes referred to as ‘modified Delphi’) to assess assumptions and estimate parameters (e.g. for economic modelling where source information is lacking or may be subject to bias. In this method a group of experts reply anonymously to questionnaires, and subsequently receive feedback in the form of a summary representation of the group response, following which each may modify their response. The process repeats itself over a number of rounds until expert consensus is reached. Key aspects of the process are selection of appropriate experts, careful construction of questionnaires and summary feedback provided iteratively to experts, and anonymity of the experts, who are therefore not influenced by the dynamics of a group discussion. There is no guarantee of reliability (different panels of experts may come to different consensus views), and so sensitivity analysis may be required to test the impact of uncertainty in parameters derived by this method. HTA agencies such as NICE generally prefer values to be derived from observational datasets than from expert opinion.
How to cite: Delphi Method [online]. (2016). York; York Health Economics Consortium; 2016. https://yhec.co.uk/glossary/delphi-method/