Slice-based cohesion metrics and software intervention

Software reconstruction is a costly endeavor, due in part to the ambiguity of where to focus reengineering effort. Cohesion metrics, and particularly quantitative cohesion metrics, have the potential to aid in this identification and to measure progress. The most extensive work on such metrics is with slice-based cohesion metrics. While their use of semantic dependence information should make them an excellent choice for cohesion measurement, their wide spread use has been impeded by a lack of empirical study. Recent advances in software tools make, for the first time, a large-scale empirical study of slice-based cohesion metrics possible. Three results from such a study are presented First, base-line values for slice-based metrics are provided These values act as targets for reengineering efforts with modules having values outside the expected range being the most in need of attention. Second, two longitudinal studies show that slice-based metrics quantify the deterioration of a program as it ages. This serves to validate the metrics: the metrics quantify the degradation that exists during development; turning this around, the metrics can be used to measure the progress of a reengineering effort. Finally, "head-to-head" qualitative and quantitative comparisons of the metrics identify which metrics provide similar views of a program and which provide unique views of a program.