Add more people is not always the best solution

A quite common "solution" when there is a risk to not reach a deadline is to add more people to the group. What I usually say is that you should do the opposite and "remove" those persons that takes time from other developers and let the group work with no disturbances. If you add more people then the velocity usually* goes down. Now I have some figures to point to when I red Mike Cohn's post regarding if it's possible to predict the team size in a sprint.

What I wanted to know was “What is the average impact of adding a person to a seven-person team?” I would have loved the answer to be something like “Velocity goes up 15%.” Unfortunately, it wasn’t that straightforward because velocity often dipped for a couple of iterations before going up.

Note that in the long term it can be better to add more people thou.

* If you add developers that know the details and can start to produce directly then the velocity can go up but that case is quite rare