Delphi technique
The Delphi technique is a method of surveying that uses repeated surveying of the same group of people (usually experts) on the same topic so they can come to a consensus. After each survey, the results are aggregated and sent to each participant so they can be informed before the next survey and adjust their answers if necessary. Through repeated rounds of surveys, the group may be able to come to a consensus.
See also: survey, questionnaire