What's your team BMI?

Just like the American waistline, the size of teams is increasing — at an alarming rate. At Kellogg, we've tracked over 1,200 managers and leaders in business and government covering large and small organizations and they have one unenviable common denominator: their teams are too darn big.

In our data, the average team size prior to 2003 (a little more than 10 years ago) was 12.49 people. However, between 2009-2012, the average team size rose to 15.21 people! In other words, team size increased by nearly three people in less than a decade!

By overstocking the team, you open a Pandora's Box of problems. Free riders are more likely to emerge as teams grow in size. Communication problems increase exponentially. (When recently attempting to schedule a meeting, for example, a Northwestern University task force team discovered that there was no time or day of the week that all members had free.)

As a general guiding principle, teams should contain the fewest number of people necessary to accomplish the goal. So how to build a leaner team? Follow these principles:

Teams should be the exception, not the rule. Don't create a team when you or somebody else can accomplish the goal single-handedly. If you (or another expert) can accomplish the goal, use the "benign dictator" model — let the talented member do the work. Save teamwork for challenges that cannot be solved through the brains and effort of a single individual. Then, the whole can be greater than the sum of the parts.

Build the team one member at a time. Recruit members on an individual basis and candidly ask what that person is adding above and beyond the existing membership. We often are too quick to be inclusive for social-political reasons, and this is not serving our goals. Teams should not be composed of personalities, but of competencies. By building the team one member at a time, we think carefully about the added value of the next member, and it sets the stage for maximizing diversity.

Follow the visiting relative model. Think of your team as a nuclear-family unit that may occasionally bring in relatives for information, expertise and insight. Then, send those relatives away after they have stayed a day or two. In my research on teams that change composition, we've found that outsiders can often jump-start creative thinking even when it is clear to all that this is not a permanent assignment.

Have an oddball. Literally. Research by Tanya Menon and Kathy Phillips in Organization Science reveals that odd-numbered teams are more harmonious than even-numbered teams. Why? Odd-numbered teams often lack stable, permanent coalitions, means they have to argue and articulate their differences.


For more on right-sizing your team, see Prof. Leigh Thompson's Creative Conspiracy (Chapter 3) and Making the Team: A Guide for Managers (Chapter 2).