Nejde o přepočet na radiány. Jde o vážený součet 4 metrik. Prostě usoudili, že pro udržovatelnost jsou ty metriky důležité právě v tomto poměru:
The Software Maintainability Index (MI) is a single-value indicator for the maintainability of a software system. It was proposed by Oman and Hagemeister in the early nineties [1]. The Maintainability Index is computed by combining four traditional metrics. It is a weighted composition of the average Halstead Volume per module, the Cyclomatic Complexity, the number of lines of code (LOC) and the comment ratio of the system.