Estimation of Responsibility Metrics to Determine Package Maintainability and Testability

Many costly software issues exist due to poorly designed systems and due to systems which are not easy to test or maintain because of poor designs. R. C. Martin began with a set of object oriented design principles and designed his metrics based on these principles. In a previous paper [2], we began with Martin´s principles and used them to modify his coupling, instability and abstractness metrics. We modified Martin´s metrics based on the concept of responsibility, our motivation is that packages with different levels of responsibility should have different weights with respect to the coupling, instability and abstraction metrics. In this paper, we present an experimental study to validate the modified metrics by showing their relationship to maintainability and testability, and then we construct prediction models for these two external quality attributes. The study results indicate that the new metrics are very promising and lead to improved results.