How big should your team be? Well it depends on what your most important goal is:
- If you are trying to keep costs down, a team size of 3 people or less is optimal.
- If you are trying to get a result as quickly as possible, a team size of 5 to 7 people is optimal.
- If you are trying to hit a budget or deadline as accurately as possible, again a team size of 5 to 7 people is optimal.
- If you are trying to burn a large budget, team sizes of 9 and up are best. These effects appear to be exponential.
Is item 4 really a goal? Nevermind. Silly question.
I think this data explains the Guidewire approach of keeping teams between 3 and 6 people. In effect, this has them cycling between lowest cost and fastest delivery, which is probably a sweet spot to find yourself in.
OTOH - This study is largely based on waterfall projects. Does anyone have the data to create a similar study of agile projects?