“Resolved” can be changed by any other status used in the issue tracking tool the company uses. Other statuses commonly used are “to be tested”, “fixed” or “ready for test”. In this case it means that development has fixed something and Software Testing can start checking if it is actually fixed (or not).
When releasing, you would like to know if every issue that was found and fixed has actually been fixed. As software tester, you should not simply rely on the blue eyes of the developers but verify it has actually been fixed.
How to measure
Count all defects with status resolved with a specific product version <= to be released version.
With every release, all defects with status resolved should have been re-tested. This means there should be no defects with this status and release version when releasing. However, since this only relates to a release (some issues cannot be retested until just before the release), the target that is set for this metric should not be 0 but as low as possible.
Urge software testers to close
Have quality pizza nights to close the issues
Whenever there is time left, this can fill that gap