To test or to inspect, what is the coverage?

As a test engineering community we have been fighting to standardize on a method to provide a realistic means to calculate board coverage at test. We have made progress with certain equipment types like in-circuit test (ICT), but have been unsuccessful to date encompassing the full spectrum of test and even less successful at accommodating the full manufacturing process. Bottom line is that we can calculate test coverage for a single test process based upon the capability of the equipment that we are using, but we can´t calculate defect coverage for all test processes.