The Maths of a Project Manager in Scrum
Did you ever hear about the internal conflict of a Project Manager?
Three forces are battling inside one person. People, Process and Product, each with its weapon.
PM is forced to bring profit from the product, manage people and try to handle the process of creation. This is as opposite as it can be, the logic will always keep thinking about short term, cutting quality and crunching people.
So, what if we separate those areas? Let’s do the math:
Project = Product + Process
Manager = Money + People
And the one that has the money can own, thus:
Project Manager – People – Process = Product Owner
Hm… interesting. Let’s see how does this resonate with our croocked triangle.
The Development Team takes care of their own and the Scrum Master is there to guard the process. And everyone is balanced and happy!
By this time you surely realized that I can’t draw nor write straight using a tablet. This revelation is a bonus and you’ll be seeing more of that 
Credits:
A post by a fellow Scrum.org trainer, Ralph Jocham finally made me put that on (electronical) paper. Thanks Ralph!
You can find his post here: http://agiletips.blogspot.com/2012/04/separation-of-power-in-scrum.html?m=1
The math is missing an important component: ROI.
Project Manager – People – Process + ROI = Product Owner
Unlike a project manager, whose job it is to ensure that that the project stays in budget, the Product Owner must ensure that that the money is well spent. If it is not s/he is expected to stop development!
In the classical approach, the responsibility for ROI is often spread across finance, product management and project management, meaning no one is really responsible for it.
That’s a very valid point – thank you, Peter.
It’s really overlooked by many organizations that the ROI responsibility should be concentrated in one point. In modern, project-driven companies it’s a standard, but unfortunately these kinds of companies are rare …
Kate