  The pull-based development process has become prevalent on platforms such as
GitHub as a form of distributed software development. Potential contributors
can create and submit a set of changes to a software project through pull
requests. These changes can be accepted, discussed or rejected by the
maintainers of the software project, and can influence further contribution
proposals. As such, it is important to examine the practices that encourage
contributors to a project to submit pull requests. Specifically, we consider
the impact of prior pull requests on the acceptance or rejection of subsequent
pull requests. We also consider the potential effect of rejecting or ignoring
pull requests on further contributions. In this preliminary research, we study
three large projects on \textsf{GitHub}, using pull request data obtained
through the \textsf{GitHub} API, and we perform empirical analyses to
investigate the above questions. Our results show that continued contribution
to a project is correlated with higher pull request acceptance rates and that
pull request rejections lead to fewer future contributions.
