If you are interested in improving the quality and specifically the maintainability of the software you produce, then you will have very likely asked yourself one of these questions:
"How well is my system doing in comparison to others?" "Which of our projects are not doing so well?" "Where do I have a serious problem and need to act right away?" "How can I make sure that my system is improving over time?"
And most likely, you will also have asked yourself: "Is there not one single number that can answer oll of these questions for me?"
Can we take all the complex quality measurements that are possible (clone coverage, test coverage, structure metrics, open field defects, pending reviews, …) and aggregate them into one KPI?