In more recent applications of this method the term a ‘modified Delphi study’ is often used to describe the research method used when one or more of the ‘rules’ of a Delphi study was deliberately omitted from the study design. This does not mean the method is no longer valid. It simply means that the study design is based on Delphi principles, but modifications have been made to accommodate local requirements: panel members might be engaged in some form of face-to-face contact; definitions of ‘expert’ are perhaps more loosely applied; and so on.