This paper looks at a problem where a group, made up of individuals from a variety of different organizations but with similar technical backgrounds, had the task of producing a forecast for their particular industry. The forecast was to be published by the technical institute, and was therefore of general interest in stimulating debate. The group members used a form of judgmental modeling to produce both their individual and group result. After the initial outcome the large group was split into three sub-groups, based upon a method of psychological profiling. The results presented here show how different psychological groups behave in their individual decision making, and how the group composition affects the smaller group final forecast. The outcomes of the study have implications for decision making aids using IT/IS, both for systems that aim to facilitate and for those that attempt to model the process e.g. negotiation models. Although only a small experiment, the research results suggest that there is tremendous potential benefit from this avenue of research when applied to the developing technologies of group decision and negotiation systems.