  Context: Many studies consider the relation between individual aspects and
bug-introduction, e.g., software testing and code review. Due to the design of
the studies the results are usually only about correlations as interactions or
interventions are not considered.
  Objective: Within this study, we want to narrow this gap and provide a broad
empirical view on aspects of software development and their relation to
bug-introducing changes.
  Method: We consider the bugs, the type of work when the bug was introduced,
aspects of the build process, code review, software tests, and any other
discussion related to the bug that we can identify. We use a qualitative
approach that first describes variables of the development process and then
groups the variables based on their relations. From these groups, we can induce
how their (pair-wise) interactions affect bug-introducing changes.
