If you consider that the project management is a percentage of the total project cost, it appears to me that this percentage varies with the size of the project (not considering the hidden costs). Consider the case of software development project. How would that curve (cost of management versus total cost) appear like?

In my experience as a software development project manager for a consulting / developing firm we added 25% – 35% of project management cost ON TOP of the actual development cost.

The reasoning for this is that the PM is the link between the customer of the project and the developers. Often they speak two different languages and you need the PM in between in order to "translate".

The range of 25% – 35% depended on the customer. If we knew that the customer was "easy" to deal with, then we could usually get away with only adding 25%. But if the customer required more hand holding and was generally "difficult" then we went as high as 35% because the PM would need to invest a lot more time into the project.

Until next time,
Cornelius Fichtner, PMP
The Project Management PrepCast™ – http://www.pm-prepcast.com
The Project Management Podcast™ – http://www.thepmpodcast.com