Evaluating the software quality non-functional requirement through a fuzzy logic-based model based on the ISO/IEC 25000 (SQuaRE) standard

Software quality measurement is an essential task in any software related project. Throughout the years many software quality models have been proposed defining a set of quality elements that have to be measured in order to evaluate the software quality. However currently, there is no standard to measure any of the non-functional requirements, instead there are models that provide a characterization for a particular non-functional requirement, including the software quality (ISOnEC 25000). Even if this model provides a common base for quality measurement, most of the defined characteristics are qualitative, thus their measurement are complicated, very often subjective, with a limited scope mostly particular, and not necessarily follow the measurement principles, which limiting the comparison. Additionally, uncertainty and lack of information are also present in software projects, making it harder to measure the overall software quality. Because of these issues, better methods for software quality evaluation have to be used. In this paper a fuzzy logic-based model is proposed for quality evaluation, aiming to handle in a formal way the uncertainty, the lack of information and enable the possibility to compare quantitatively the quality evaluation at distinct levels. The model was tested by measuring nine real life projects and obtaining conclusions about the quality of each project.