Influence of team size and defect detection technique on inspection effectiveness

Inspection ream size and the set of defect detection techniques used by the team are major characteristics of the inspection design, which influences inspection effectiveness, benefit and cost. In this work we focus on the inspection performance of a nominal, that is n on-communicating, team, similar to the situation of an inspection team afte r independent individual preparation. We propose a statistical model based on empirical data to calculate the expected values for the inspection effec tiveness and effort of synthetic nominal teams. Further we introduce an eco nomic model to compute the inspection benefits, net gain, and return on inv estment. With these models we determine a) the best mix of reading techniqu es (RTs) to maximize the average inspection performance for a given team si ze, b) the optimal ream size and RT mir for a given inspection time budget, and c) the benefit of an additional inspector for a given team size. Main results of the investigation with data from a controlled experiment ar e: a) Benefits of an additional inspector for a given RT diminished quickly with growing team size. Thus, above a given team size a mix of different R Ts is more effective and has a higher net gain than using only one RT; b) T he cost-benefit model limits team size, since the diminishing gain of an ad ditional inspector at some point is more than offset by his additional cost .