Investigating the influence of inspector capability factors with four inspection techniques on inspection performance

We report on a controlled experiment with over 170 student subjects to investigate the influence of inspection process, i.e., the defect detection technique applied, and inspector capability factors on the effectiveness and efficiency of inspections on individual and team level. The inspector capability factors include measures on the inspector's experience, as well as a pre-test with a mini-inspection. We use sampling to quantify the gain of defects detected from selecting the best inspectors according to the pre-test results compared to the performance of an average team of inspectors. Main findings are that inspector development and quality assurance capability and experience factors do not significantly distinguish inspector groups with different inspection performance. On the other hand the mini-inspection pre-test has considerable correlation to later inspection performance. The sampling of teams shows that selecting inspectors according to the mini-inspection pretest considerably improves average inspection effectiveness by up to one third.