thesis - Faculty of Information and Communication Technologies ...

Chapter 5. Growth Dynamics
4. The popularity of a class is not a monotonic function of its size or
complexity (as captured by our 10 metrics). In other words, large
and complex classes are no more popular than small and simple
classes.
5. The process of software evolution in general causes popular classes
to gain additional dependents and hence become even more popular.
5.5 Discussion
In this section, we discuss how developers choose to maintain software
systems by interpreting the observations presented in the previous section.
Specifically, we argue that though the different metrics selected
are strongly correlated, the inconsistency of the strength between different
systems warrants the use of different metrics in order to understand
the maintenance of a software system effectively. Furthermore,
we discuss the finding of the consistent increase in the Gini Coefficient
value of the In-Degree Count and argue that this observation provides
the empirical support for the preferential attachment model that has
previously been postulated as one of the likely models of growth. We
also present an explanation for the observation of highly stable and
strongly bounded range for the Gini Coefficients and show that the decisions
that developers make with respect to how they organise a solution
are highly consistent during the development life cycle. Additionally,
we present our interpretation for why developers prefer to construct
and maintain solutions with highly skewed distributions where much
of the functionality is centralised into a few god-like classes. We end
the section with a discussion on the value and applicability of the Gini
Coefficient for identifying releases with significant changes as well as
for detecting the presence of machine generated code.
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