The proportion of different parts to make a whole.
Team size and composition affect team processes and outcomes. The optimal size and composition of teams depends on the scope of the team's goals. With too few people, a team will not have the resources and skills it needs to complete its tasks. Too many members can make communication and coordination difficult and lead to poor team performance.
Research shows that teams perform best with between five and nine members. Dr. Meredith Belbin did extensive research on teams prior to 1990 in the UK that suggested that the optimum team size is eight roles plus a specialist as needed. Fewer than five members resulted in decreased perspectives and diminished creativity. Membership in excess of twelve resulted in increased conflict and greater potential of subgroups forming that can disrupt team cohesion.
The mix of knowledge and expertise on a team is also important. Individuals should be selected for teams so that as a whole the group has all the expertise needed to achieve its goals. For this reason, cross-functional teams may be larger than groups formed to work on less complex activities. Similarly, a task force charged with making recommendations in a short time frame would benefit from having fewer members.
Teams benefit from similarities in background among members, which can reduce conflict and miscommunication. Having fewer differences can also reduce the amount of time a team takes to become an effective working group since there is less need to adjust individual work styles. On the other hand, more diversity in skills and experience brings broader perspectives and different approaches to the team's work. Having members with different skill sets also reduces redundancies and allows for the more efficient assignment of people to various teams.