Empirical Comparison of two Metrics Suites for Maintainability Prediction in packages of Object-Oriented Systems: a Case Study of Open Source Software

Software maintainability has been an important external quality attribute that concerns both styles of software development, the proprietary model as well as open source. As lots of open source software are predominantly built using the OO paradigm, there exists a need for empirical validation with respect to certain quality aspects especially maintainability. There are a few studies in the past which use code metrics and a few which use design metrics, much earlier in the software development life cycle to predict maintainability. In addition, there are studies which apply both code as well as design metrics to evaluate maintainability. The objective of this research is to perform an empirical comparison of two popular OO metrics suites, the Martin suite and the CK suite on four open source software systems by analysing a few key design metrics such as size, coupling, complexity, inheritance and stability. Two important observations were made with this empirical study. First, between the two OO suite of design metrics, the prediction model developed using Martin metrics scores better than the model developed using the CK suite. Second, the combination of Martin and CK suites is helpful in predicting the maintainability of OO software, with a predictive accuracy of 66.7%, better than that of the models constructed by either Martin metrics or by the CK metrics individually.