For two decades, software inspections have proven effective for detecting defects in software. We have reviewed the different ways software inspections are done, created a taxonomy of inspection methods, and examined claims about the cost-effectiveness of different methods.

We detect a disturbing pattern in the evaluation of inspection

methods. Although there is universal agreement on the effectiveness of software inspection, their economics are uncertain. Our examination of several empirical studies leads us to conclude that the benefits of inspections are often overstated and the costs (especially for large software developments) are understated. Furthermore, some of the most influential studies establishing these costs and benefits are 20 years old now, which leads us to question their relevance to today's software development processes.

Extensive work is needed to determine exactly how, why, and when

software inspections work, and whether some defect detection techniques might be more cost-effective than others. In this article we ask some questions about measuring effectiveness of software inspections and determining how much they really cost when their effect on the rest of the development process is considered. Finding answers to these questions will enable us to improve the efficiency of software development. (Also cross-referenced as UMIACS-TR-95-104)