Traditionally quality is objectively measured in number of tests passed. For a bolt it is whether it's various measurements and dimensions fall within a given tolerance. The same with electronic components. For software it's usually a matter of how many tests it successfully passes (for test driven development) or how many of the design specifications materialized (for up-front design development). Of course since most software (including games) is developed using code and fix, there is no way you can credibly claim any type of quality.