Many debugging tools rely on compiler-produced metadata to present a source-language view of program states, such as variable values and source line numbers. While this tends to work for unoptimised programs, current compilers often generate only partial debugging information in optimised programs. Current approaches for measuring the extent of coverage of local variables are based on crude assumptions (for example, assuming variables could cover their whole parent scope) and are not comparable from one compilation to another. In this work, we propose some new metrics, computable by our tools, which could serve as motivation for language implementations to improve debugging quality.