It seems to me that the safest bet is to measure the number and priority of verified requirements. This has three key benefits:
- The focus shifts to requirements, which moves the effort earlier in the development cycle where it belongs.
- It reveals the inventory of functionality that the system contains. Most managers don't really grasp the enormity of what QA is up against in trying to provide comprehensive coverage.
- Requirements may be reduced if schedules need to be sacrificed. Related risks can be managed instead of just blindly cutting corners or letting serious defects go.
Do your teams' measurements for success highlight failure? How does your team strive for success? What works for you?