The Optimum Team Size

  1. The optimum team size is 5.

Johanna Rothman at ITJOBBLOG has a great article called Why Team Size Matters. Her argument is that teams of more than 9 people lose the intimacy required to function effectively due to the non-linear way communication paths expand as you add people.

4 people, (16-4)/2=6 5 people, (25-5)/2=10 6 people, (36-6)/2=15 7 people, (49-7)/2=21 8 people, (56-8)/2=24 9 people, (81-9)/2=36 10 people (100-10)/2=45 *Communication Paths=(N*N-N)/2
I hadn't seen it presented in that way before, but it matches up with my experiences. I'd say 5 is the sweet spot. Your group's resemblance to a herd of cats will increase logarithmically as you expand past that. Get smaller and you're apt to run short on brains.