The Quamoco Product Quality Modelling and Assessment Approach

Published software quality models either provide abstract quality attributes or concrete quality measurements. There are no models that seamlessly integrate both aspects. In the project Quamoco, we developed a comprehensive approach with the aim to close this gap. For this, we developed in several iterations a meta quality model specifying general concepts, a base quality model covering the most important quality factors and a quality assessment approach. The meta model introduces the new concept of a product factor, which bridges the gap between concrete measurements and abstract quality aspects. Product factors have measures and instruments to operationalise quality by measurements from manual inspection and tool analysis. The base model uses the ISO 25010 quality attributes, which we refine by 200 factors and 600 measures for Java and C# systems. We found in several empirical validations that the assessments results fit to the expectations of experts for the corresponding systems. The empirical analyses also showed, however, that partly the correlations are not significant and that the maintainability part of the base model has the highest correlation, which fits to the fact that this part is the most comprehensive. Although we see still a lot of room for extending and improving the base model, it shows a high correspondence with expert opinions and hence is able to form the basis for a repeatable and understandable quality assessment in practice.