  The open source development community consists of both paid and volunteer
developers as well as new and experienced users. Previous work has applied
social network analysis (SNA) to open source communities and has demonstrated
value in expertise discovery and triaging. One problem with applying SNA
directly to the data of the entire project lifetime is that the impact of local
activities will be drowned out. In this paper we provide a method for
aggregating, analyzing, and visualizing local (small time periods) interactions
of bug reporting participants by using the SNA to measure the betweeness
centrality of these participants. In particular we mined the Android bug
repository by producing social networks from overlapping 30-day windows of bug
reports, each sliding over by day. In this paper we define three patterns of
participant behaviour based on their local centrality. We propose a method of
analyzing the centrality of bug report participants both locally and globally,
then we conduct a thorough case study of the bug reporter's activity within the
Android bug repository. Furthermore, we validate the conclusions of our method
by mining the Android version control system and inspecting the Android release
history. We found that windowed SNA analysis elicited local behaviour that were
invisible during global analysis.
