Practical lessons for improving software quality

Discussed is a retrospective study of the errors uncovered in developing a multiple-release industrial software product of some 60000 lines of C source code. The purpose of the study was to determine what changes in existing software development procedures would detect errors earlier in the life cycle, where they are less expensive to correct. The study procedure consisted of three tasks: establishing criteria for sorting the problems into software development errors and other problems/errors, determining error classes for categorizing the development errors, and identifying a series of ten error-detection steps within the software development process. A number of results specific to this study are presented, and conclusions are drawn and recommendations made regarding functional and design errors