A quality cost reduction model for large-scale software development

Understanding quality costs is recognized as a prerequisite for decreasing the variability of the success of software development projects. This paper presents an empirical quality cost reduction (QCR) model to support the decision-making process for additional investment in the early phases of software verification. The main idea of the QCR model is to direct additional investment into software units that have some fault-slip potential in their later verification phases, with the aim of reducing costs and increasing product quality. The fault-slip potential of a software unit within a system is determined by analogy with historical projects. After a preliminary study on a sample of software units, which proves that we can lower quality costs with additional investment into particular verification activities, we examine the effectiveness of the proposed QCR model using real project data. The results show that applying the model produces a positive business case, meaning that the model lowers quality costs and increases quality, resulting in economic benefit. The potential to reduce quality costs is growing significantly with the evolution of software systems and the reuse of their software units. The proposed model is the result of a research project performed at Ericsson.