The Delphi method ensured early contributions were made without the influence of other group members
The three rounds of Delphi method were critical to the development of the final list. In particular, the comments from the experts in Round Two and associated workshops were invaluable in dealing with the challenge of choosing a single core concept from a cluster of related terms. For example, numerous expert comments were received regarding the related terms margin of safety, therapeutic window, andtherapeutic index. These comments informed the final decision to propose therapeutic index in Round Three and subsequent 90% endorsement of this concept. This is consistent with earlier findings supporting the use of three rounds of expert analysis (Hallowell & Gambatese, 2010). An innovative part of our Delphi method was the use of workshops between Rounds Two and Three, with workshop discussions useful in shaping the clustering of terms around a central concept. The workshops also permitted discussion and input from a wider team outside of the core research team. That said, the workshops may have affected the independent nature of the expert ratings on the final Delphi round, so only the expert group ratings in the first two rounds were truly independent.