Reusability Index: A Measure for Assessing Software Assets Reusability

The reusability of assets is usually measured through reusability indices. However, these indices either do not synthesize their constituent metrics into an aggregate or they do not capture all facets of reusability, such as structural characteristics, external qualities, and their documentation. To alleviate these shortcomings, we introduce a reusability index (REI) as a synthesis of various software metrics that cover a number of related reusability aspects. Furthermore, we evaluate its ability to quantify reuse, by comparing it to existing indices through a case study on 15 reusable open-source assets (i.e., libraries and frameworks). The results of the study suggest that the proposed index presents the highest predictive and discriminative power, it is the most consistent in ranking reusable assets, and the most strongly correlated to their levels of reuse.