Software Defect Density variants: a proposal

Defect density (DD) is an important measure of software quality, but its usual definition (number of defects found divided by size in lines of code (loc)) is high level and may lead to different interpretations. The objective is to define concrete variants of Defect Density (standard DD, differential DD), analyze their trend over time on a number of projects, and understand which one is more suitable as an indicator of the quality of software projects. In the three projects analyzed the two variants of defect density have distinctly different trends over time; differential DD has a large variability, while standard DD has a steadily increasing trend. The conclusion is that both standard and differential DD are useful variants of DD, the standard DD providing a global quality view of a project (i.e. considering all the history) and the differential DD providing a local quality view (i.e. specific to one version). However, further studies are needed to investigate the usage of these variants