Small teams beat large teams in software development

A study done by consultancy QSM in 2005 seems to indicate that smaller teams are more efficient than larger teams. Not just a little more efficient, but dramatically more efficient. QSM maintains a database of 4000+ projects. For this study they looked at 564 information systems projects done since 2002. (The author of the study claims their data for real-time embedded systems projects showed similar results.) They divided the data into “small” teams (less than 5 people) and "large" teams (greater than 20 people).

To complete projects of 100,000 equivalent source lines of code (a measure of the size of the project) they found the large teams took 8.92 months, and the small teams took 9.12 months. In other words, the large teams just barely (by a week or so) beat the small teams in finishing the project!

Given that the large teams averaged 32 people and the small teams averaged 4 people, the cost of completing the project a week sooner with the large team is extraordinary: at $10,000 per person-month (fully loaded employee cost), the large teams would have spent $1.8M while the small teams only spent $245k. I can’t think of too many situations where gaining one week in the schedule could possibly justify this cost differential.

Original Article: Daniel Miessler

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