« Adding manpower to a late software project makes it later »

Say in different way : « You will need always 9 month to build a baby even if you recruit 9 women ».

The hypothesis is that most of the tasks are not partitionable and the new people will only make actual team to lose time in communication.

This lost time is proportional to n(n-1) (where n is the number of people). Applying the Brooks Law or not it is clear thaht more the Team is big more you need to spend time on communication. If we use a real image, if you are 300 people in a 30 m² kitchen, there is less chance to be able to do the work of 3 peoples.

Frederick Brooks received the Alan M. Turing price in 1999 for his works in the IT architecture, operating systems and software, in particular for the set-up of IBM OS/360 Operating Systems.