A Knowledge-Based Cohesion Metric for Object-Oriented Software

This paper presents Percentage of Shared Ideas (PSI), a metric for measuring the semantic cohesion of a class in object-oriented software. PSI uses information in a knowledge base to quantify the cohesiveness of a class’s task in the problem domain, allowing a clearer view of cohesion than code syntax provides. Furthermore, this metric is independent of code structure and could be calculated before implementation, providing clues to design flaws earlier in the software development cycle, when changes are less expensive. In this paper, we define the PSI metric, provide theoretical and empirical validation, and compare PSI to well-known cohesion metrics.