  Context: Large-scale distributed projects are typically the results of
collective efforts performed by multiple developers with heterogeneous
personalities. Objective: We aim to find evidence that personalities can
explain developers' behavior in large scale-distributed projects. For example,
the propensity to trust others - a critical factor for the success of global
software engineering - has been found to influence positively the result of
code reviews in distributed projects. Method: In this paper, we perform a
quantitative analysis of ecosystem-level data from the code commits and email
messages contributed by the developers working on the Apache Software
Foundation (ASF) projects, as representative of large scale-distributed
projects. Results: We find that there are three common types of personality
profiles among Apache developers, characterized in particular by their level of
Agreeableness and Neuroticism. We also confirm that developers' personality is
stable over time. Moreover, personality traits do not vary with their role,
membership, and extent of contribution to the projects. We also find evidence
that more open developers are more likely to make contributors to Apache
projects. Conclusion: Overall, our findings reinforce the need for future
studies on human factors in software engineering to use psychometric tools to
control for differences in developers' personalities.
