Abstract
Code review is advocated as one of the best practices to improve software quality and reduce the likelihood of introducing defects during code change activities. Recent research has shown how code components having a high review coverage (i.e., a high proportion of reviewed changes) tend to be less involved in post-release fixing activities. Yet the relationship between code review and bug introduction or the overall software quality is still largely unexplored. This paper presents an empirical, exploratory study on three large open source systems that aims at investigating the influence of code review on (i) the chances of inducing bug fixes and (ii) the quality of the committed code components, as assessed by code coupling, complexity, and readability. Findings show that unreviewed commits (i.e., commits that did not undergo a review process) have over two times more chances of introducing bugs than reviewed commits (i.e., commits that underwent a review process). In addition, code committed after review has a substantially higher readability with respect to unreviewed code.