3.2.2 Group size

Another significant feature of a work group is its size. To be effective it should be neither too large nor too small. As membership increases there is a trade-off between increased collective expertise and decreased involvement and satisfaction of individual members. A very small group may not have the range of skills it requires to function well. The optimum size depends partly on the group's purpose. A group for information sharing or decision making may need to be larger than one for problem solving.

A simple calculation can indicate how quickly the number of two-way interactions in a group increases with increasing size. In a group of N people (where N stands for a number) each of the N individuals relates with N × 1 others, so there are N × (N − 1) / 2 possible interactions.

In many organisations, there is a tendency to include representatives from every conceivable grouping on all committees in the belief that this enhances participation and effectiveness. There is also the view that putting a representative of every possible related department into a given group helps smooth information flow and project progress. In practice, communication is usually reduced in larger groups. As the group size grows, members feel less involved in the process, alienation tends to increase and commitment to the project tends to decrease. The numbers most commonly quoted for effective group size in a face-to-face team are between 5 and 10, so reducing the number of interactions and lessening the risk of conflict.

There is a nice demonstration that the 'between 5 and 10' rule is due to communication limitations. If we devise special procedures to manage the interpersonal exchanges (as in some computer-based brainstorming systems, where the computers handle all the gathering and feeding back of ideas) the advantages of the small group disappears: the larger the group, the more ideas are generated.

However, in the normal face-to-face mode, if there are more than about 12 members in our team we are likely to encounter group-size problems. If the numbers cannot be reduced we might consider restructuring the team into sub-groups and delegating responsibility for achieving some of the team's objectives. We may find that if we don't do this deliberately it will happen anyway. For instance, members who like each other or share common interests may spontaneously form sub-groups.

Unfortunately, the breakdown of large groups into sub-groups and cliques may not help a team achieve its goals. One device for keeping large numbers of people informed about a project is for a small group to manage the task and for it to invite relevant people to attend particular meetings. Alternatively, the small group can arrange to give information seminars to larger groups of colleagues. So, for the purposes of achieving team goals it is better that the process of restructuring big groups into smaller groups is managed consciously and carefully.