On the evaluation of software inspections and tests

The goal of software inspections and tests is to reduce the expected cost of software failure over the life of a product. This paper extends the use of defect triggers, the events which cause defects to be discovered, to help evaluate the effectiveness of inspection and test activities. In the case of inspections, the defect trigger is defined as a set of values which associate the skills of the inspector with the discovered defect. Similarly, for tests, the defect trigger values embody the various strategies being used in creating test scenarios. The usefulness of triggers in evaluating the effectiveness of software inspections and tests is demonstrated by evaluating the inspection and test activities of some software products. These evaluations are used to point to both deficiencies in inspection and test strategies, and progress made in improving such strategies.