The impact of software process improvement on quality: in theory and practice

To remain competitive, software companies must establish practices that enhance quality and advance process management. To this end, they have increasingly turned to software process improvement (SPI) methodologies, of which the ISO 9000 standards and the capability maturity model (CMM) are the best known. The underlying principle of both methodologies is to assess organizational capabilities to produce quality software, but they depend on different underlying processes. Whether the practices advocated by these methodologies lead to high-quality software has been the topic of ongoing debates. Both scholars and practitioners are looking for hard evidence to justify the time and effort required by such guidelines to improve the software-development process and its end product. In this paper, we investigate the impact of SPI methodologies on software quality, first by theoretical comparison and then with empirical data. Our findings reveal that each methodology has had a different level of impact on software quality factors. These findings could help software-development organizations select the methodology or combination that best meets their quality requirement.