Are the perspectives really different? Further experimentation on scenario-based reading of requirements

Perspective-Based Reading (PBR) is a scenario-based inspection technique where several reviewers read a document from different perspectives (e.g. user, designer, tester). The reading is made according to a special scenario, specific for each perspective. The basic assumption behind PBR is that the perspectives find different defects and a combination of several perspectives detects more defects compared to the same amount of reading with a single perspective. This paper presents a study which analyses the differences in perspectives. The study is a partial replication of previous studies. It is conducted in an academic environment using graduate students as subjects. Each perspective applies a specific modelling technique: Use case modelling for the user perspective, equivalence partitioning for the tester perspective and structured analysis for the design perspective. A total of 30 subjects were divided into 3 groups, giving 10 subjects per perspective. The analysis results show that (1) there is no significant difference among the three perspectives in terms of defect detection rate and number of defects found per hour, (2) there is no significant difference in the defect coverage of the three perspectives, and (3) a simulation study shows that 30 subjects is enough to detect relatively small perspective differences with the chosen statistical test. The results suggest that a combination of multiple perspectives may not give higher coverage of the defects compared to single-perspective reading, but further studies are needed to increase the understanding of perspective difference.