I am about to participate in a discussion with management regarding measuring our testing efficiency as a QA organization. The main reason behind this is that half of our team is contracted out and our business would like to provide some metrics of how effective/efficient we are, so that we have basis data on which to negotiate contract parameters with the service agreement of our contractors.
I have poked around a little and most of the opinion I have found on this subject revolves around developer efficiency: lines of code, story points delivered, defects introduced, etc.
But what about testers? Our testing is mostly requirements based, and a mix of manual, semi-automated, and automated testing (not because we haven't gotten around to automating everything, but because some things are not automatable in our test system).