Team Tactics: Does Size Matter?

Designing Teams - Does Size Matter?
by Sharon Feltham, Excellerate

Small is definitely the secret to success when it comes to productive teams. Research has shown (and experience confirms) the optimum size for a team ranges between 5-9 people. An example of this research comes from Professor Dunbar, an anthropologist at the University College of London, who produced a paper ("The Co-Evolution Of Neocortex Size, Group Size And Language In Humans") in which he he stated:

"... there is a cognitive limit to the number of individuals with whom any one person can maintain stable relationships, that this limit is a direct function of relative neocortex size, and that this in turn limits group size ... the limit imposed by neocortical processing capacity is simply based on the number of individuals with whom a stable inter-personal relationship can be maintained"

In other words, if you have more than 10-12 people the connections between team members are too hard for us to make and maintain

Why are Smaller Teams Better?

Just Right?

Teams of 5 - 9
This size team provides sufficient numbers to foster diversity as well breadth of skill and experience.
There is some protection against the loss of a key person.
Focus (on goals) and accountability (for results) are more easily achieved
Individual performance is not overcome by group dynamics (see social loafing below)
There is minimum communication complexity amongst team members.
It doesn't require significant management overhead.

Too Small?

Teams of less than 5
Very small teams are highly dependent on the skills of the individual
They can be unstable because they are susceptible to the absence or loss of members
They lack sufficient resource and can easily split into factions

Too Big?

Teams of more than 10
Large teams quickly gravitate toward the average skill set of the group
Large teams experience communication problems.
Team members don’t get enough individual attention due to lack of time available to maintain relationships. Significantly more effort must be spent on the core socialisation necessary to keep the group functioning
Social Loafing tends to increase with team size. It’s one of the main reasons groups sometimes perform less effectively than the combined performance of members working as individuals. Social loafing is where team members make less effort to achieve a goal when they work in a group than when they work alone. The main reason for this is that people can feel unmotivated when working in a group because they think their contribution will not be evaluated.
Teams start to work again when they reach around 20-25 as it’s possible to divide them into sub-teams of 5 to 9

How to identify the true size of your team
Teams may sometimes seem larger than they are because of adjunct personnel. For example:

Core members: the actual team, each one 100% dedicated to the team task
Resource team member: People with particular expertise who assist the team from time to time 
Support people: People that help the core team get stuff done
Team sponsor: A senior manager who provides direction, protection and runs interference for the team
Facilitators: Outside people who help keep the team on track

If youre having problems defining your "core" team follow the example of Harvey Robbins (co author of "Why Teams don't Work"). Robbins was once called in to talk to a Strategic Business Unit, when he entered the room he saw 74 people sitting in chairs, about eight rows deep.

"OK," he said, "who here is on the team?" All 74 hands went up.
"Uh huh. If something goes wrong, how many people here get into trouble?"
This time only about seven hands went up.
"OK. You people are the team. The rest of you are adjuncts. Go home."

Formula for Designing a Project Team
The IT Industry has developed an interesting formula for calculating the appropriate team size for its project teams based on the law of diminishing returns; i.e. there is a point where additional resources will increase the total project effort and/or schedule rather than reduce it. Adding more resources only complicates project communications and increases project management and administration.

According to the IT guys, the maximum recommended team size is equal to the square root of the total project effort (in person months). This rule of thumb provides a reasonable check of the total number of resources assigned to the project, considering the total project effort.

The maximum recommended team size assumes the following:

A person month is equivalent to 19 person days of effort
Staff assigned to the project will have average skill levels
The team size will not be constant throughout the project. Rather the project will start with the minimum required resources, ramp up to the recommended maximum (or higher) and then ramp down towards the end of the project.

For Example: Assume a total project effort of 64 person months of effort. The square root of 64 is 8. The maximum recommended team size is therefore 8.

Reference: Robbins, H and Finley M, 1995 Why Teams Don’t Work Peterson's / Pacesetter