Software Quality Economics for Combining Defect-Detection Techniques⋆

Software defect-detection techniques such as tests or reviews are still the prevalent means to assure the quality of a program. Although these techniques constitute a significant part of the overall development costs, their economics and interplay is still not fully understood. This paper proposes a model of software quality economics for defect-detection techniques with an emphasis on the combination of diverse techniques. This is important because in real development projects a technique is never used in isolation but in combination with others. This, however, makes the evaluation of a technique very difficult because of the influences of early used techniques on the ones that are later used. We base our combination economics on a model for software quality economics of single techniques and extend it by a model for the diversity of defect-detection techniques. This allows (1) to estimate the effects of a combination and (2) to remove such influences when evaluating a single technique.