How to incorporate performance measurement into a project

Hi Caleb, this is a very interesting topic. I am responsible for Project Quality in my company and also for me it is difficult to find ways
a) to rate the performance of the PMs without offending them
b) rate the success of actions I put in place to increase PMs skillset

What I currently do, lacking a better approach, is auditing and interviewing the PMs whether they are updating the Project Documents (Like Budget Burn Chart, Detailed project plan etc.) on a regular basis and observing their way of working. Has the PM changed his/her way of acting after last training/workshop etc.

But a real judgement of performance, no idea so far.
Please let me know, when you found something!

Thanks,
Torsten