Investigating the Cost-Effectiveness of Reinspections in Software Development

Software inspection is one of the most effective methods to detect defects. Reinspection repeats the inspection process for software products that are suspected to contain a significant number of undetected defects after an initial inspection. As a reinspection is often believed to be less efficient than an inspection an important question is whether a reinspection justifies its cost. In this paper we propose a cost-benefit model for inspection and reinspection. We discuss the impact of cost and benefit parameters on the net gain of a reinspection with empirical data from an experiment in which 31 student teams inspected and reinspected a requirements document. Main findings of the experiment are: a) For reinspection benefits and net gain were significantly lower than for the initial inspection. Yet, the reinspection yielded a positive net gain for most teams with conservative cost-benefit assumptions. b) Both the estimated benefits and number of major defects are key factors for reinspection net gain, which emphasizes the need for appropriate estimation techniques.