Inspection is widely believed to be one of the most cost-effective methods for detection of defects in the work products produced during software development. However, the inspection process, by its very nature, is labor intensive and for delivering value, they have to be properly executed and controlled. While controlling the inspection process, the inspection module size is a key control parameter. Larger module size can lead to an increased leakage of defects which increases the cost since rework in the subsequent phases is more expensive. Small module size reduces the defect leakage but increases the number of inspections. In this paper, we formulate a cost model for an inspection process using which the total cost can be minimized. We then use the technique of Design of Experiments to study how the optimum module size varies with some of the key parameters of the inspection process, and determine the optimum module size for different situations.
