An Analysis of the Effect of Code Ownership on Software Quality across Windows, Eclipse, and Firefox

Ownership is an important aspect of software development in large software teams. We examine the relationship between a number of ownership measures and software faults/failures in three large software projects drawn from different process domains: Windows Vista, the Eclipse Java IDE, and the Firefox Web Browser. We find that in all cases, measures based on ownership levels, such as the number of minor contributors and proportion of ownership for the top owner have a relationship with both pre-release faults and post-release failures. However, we find that the strength of the effects is related to the development process used. Vista shows the strongest relationship with ownership level, followed by Eclipse, and then Firefox. The more that a project uses an open source style process, the more that team sizes rather than ownership levels relate to failures. We also perform additional analysis of Vista to understand patterns of ownership and show its effect on fault prediction models. Finally we provide recommendations for utilization of resources such as code inspections and possible source code change policies based on our results.