thesis - Faculty of Information and Communication Technologies ...

Chapter 6. Change Dynamics
helpful, developers need more specific guidance in order for it to be applicable
in practice. Furthermore, the information needs to be available
at a level that can help in developing tools that highlight and monitor
evolution prone parts of a system as well as support effort estimation
activities.
The specific research questions that we address in this chapter are:
• What is the likelihood that a class will change from a given version
to the next?
– Does this probability change over time?
– Is this likelihood project specific, or general?
• How is modification frequency distributed for classes that change?
• What is the distribution of the magnitude of change? Are most
modifications minor adjustments, or substantive modifications?
• Does structural complexity make a class susceptible to change?
• Does popularity make a class more change-prone?
In this chapter, we address the above questions and present a set of
recommendations that can help developers to proactively monitor and
manage change. These recommendations are derived from a statistical
analysis of change in approximately 55000 unique classes across
all projects under investigation. The analysis methods that we applied
took into consideration the highly skewed nature of the metric data
distributions, something not always properly considered in previous
work [18, 19, 27, 28, 38, 93, 150, 177, 241, 255, 272].
The raw data used is this study is available as data files on the DVD
attached to this thesis. Appendix F describes the various data and
statistical analysis log files related to this chapter.
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