ODC - Orthogonal Defect Classification

6. Conclusions

This paper used defect data from a large operating system project to empirically understand the impact of defect types on the net reliability growth experienced. The analysis was complicated by the fact that defect-type information was not available in the original defect database. The goal of this study was to examine the existence of possible cause and effect relationships that allow greater understanding and control over the software development process. The study finds that:

• Sub-populations with very inflected growth curves are found to be strongly related to the number of initialization, especially missing initialization, defects. This is consistent with the proposed model, wherein inflection is claimed to be caused by dependence between defects sharing the same execution path; considering that initializations usually occur early in the code path. This observation is also useful to test case design.
• The defect types chosen provided an insight into the problems experienced in the development and their probable causes. In this product, missing function dominated the defect types. Although, in hind sight, it was known that the specification and design phases needed improvement, it is interesting that the defect type distribution specifically identified that. It is likely that this could provide early recognition of problems, yielding to in-process corrective action.