This technique was founded between 1950 and 1960, it was developed by a project called RAND. This project was begun by three men named Norman Dalkey, Nicholas Rescher, and Olaf Helmer.
This technique involves sending out random questionnaires to people that are experts in their field and getting their responses. All responses are anonymous to the researchers. When the responses are received they're aggregated and shared with the others in the group study.