Delphi with feedback of rationales: How large can a Delphi group be such that participants are not overloaded, de-motivated, or disengaged?

In this paper, we investigate the effect of Delphi group size and opinion diversity on group members’ information load as well as on their overall experience of the Delphi process - in terms of task involvement (enjoyment and interest) and in terms of group sway (the influence and helpfulness of others’ rationales). For Delphi applications involving the exchange of rationales between participants, we found no evidence that group sizes of up to 19 participants cause information overload or de-motivation and disengagement of participants.