The Delphi method is a systematic and interactive forecasting method relying on a panel of experts. In policy relevant situations Delphi is usually used to develop consensual ideas on potential policy pathways by paying attention to the integration of outlier opinions. The Delphi method consists of two or more rounds of questioning, either via personal (online or offline) questionnaires or group discussions. After each round the researchers or facilitators provide a summary of the results (incl. answers and comments provided). Questions for the next round are developed on this basis, allowing experts to reconsider their opinion in each round.