Each of the four group decision techniques has its own set of strengths and weaknesses. The choice of one technique over another will depend on what criteria you want to emphasize and the cost-benefit trade-off.
An effective group can be defined as one, which, over extended periods of time achieves a high level of task performance and keeps its human resources intact as well. Task performance refers to the effective achievement of the goals set for the group, and human resources maintenance to the high morale and satisfaction experienced by group members, their sense of pride in belonging to the group, and their psychological commitment to the group and its goals. Thus, group effectiveness refers to the task accomplishments of the group while it simultaneously maintains itself as a cohesive, satisfied and well integrated unit. In other words, an effective group continually takes care of both task performance and maintenance of its members' social relationship and satisfaction. These so not automatically happen in groups, unless members take on the responsibility for playing certain task and maintenance roles (discussed later), so that both criteria of group effectiveness are simultaneously met.