thesis - Faculty of Information and Communication Technologies ...

Chapter 2. Software Evolution
and Chapter 6) rather than observe the overall growth trend in certain
measures which is the technique employed by many earlier studies
[39, 41, 59, 85, 100, 101, 103, 119, 120, 127, 153, 171, 175, 192, 200,
217, 239, 277, 306, 310] (discussed further in the next section – Section
2.4). As a consequence our study can offer a different insight into
the laws, as well as the dynamics of change within open source software
systems.
2.4 Studies of Growth
The Laws of Software Evolution, as well as many studies over the last
few decades have consistently shown that evolving software systems
tend to grow in size [188, 192]. But, what is the nature of this growth?
In this section we summarise the current understanding of the nature
of growth in evolving software systems. In particular, we focus heavily
on studies of growth in open source software systems as they are more
appropriate for the scope of this thesis.
In studies of software evolution, the observed growth dynamics are of
interest as they can provide some insight into the underlying evolutionary
process [283]. In particular, it is interesting to know if growth
is smooth and consistent, or if a software system exhibits an erratic
pattern in its growth. For instance, managers can use this knowledge
to undertake a more detailed review of the project if development effort
was consistent, but the resulting software size growth was erratic.
Although the observed changes do not directly reveal the underlying
cause, it can guide the review team by providing a better temporal perspective
which can help them arrive at the likely drivers more efficiently.
Additionally, studies into growth dynamics also establish what can be
considered typical and hence provide a reference point for comparisons.
Lehman and his colleagues in their initial work [168] discovered and refined
[171,175] the laws of evolution (which provide a broad description
of the dynamics of software evolution), in part, from direct observations
of size growth in long lived commercial software systems.
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