Enhancing change prediction models using developer-related factors

Continuous changes applied during software maintenance risk to deteriorate the structure of a system and are a threat to its maintainability. In this context, predicting the portions of source code where specific maintenance operations should be focused on may be crucial for developers to prevent maintainability issues. Previous work proposed change prediction models relying on product and process metrics as predictors of change-prone source code classes. However, we believe that existing approaches still miss an important piece of information, i.e., developer-related factors that are able to capture the complexity of the development process under different perspectives. In this paper, we firstly investigate three change prediction models that exploit developer-related factors (e.g., number of developers working on a class) as predictors of change-proneness of classes and then we compare them with existing models. Our findings reveal that these factors improve the capabilities of change prediction models. Moreover, we observed interesting complementarities among the prediction models. For this reason, we devised a novel change prediction model exploiting the combination of developer-related factors and product and evolution metrics. The results show that such a combined model is up to 22% more effective than the single models in the identification of change-prone classes.