thesis - Faculty of Information and Communication Technologies ...

Chapter 3
Data Selection Methodology
Empirical research by its very nature relies heavily on quantitative information.
In our study, we extract information from a number of different
Open Source Software Systems. This chapter provides an overview of
the various sources of information that can be used to study evolution,
the Open Source Software Systems that we selected, and the criteria
used to select the software systems.
3.1 Evolution History
Research into software evolution relies on historical information. When
information is extracted from various data sources (for example, source
code, project plans, change logs etc.) of a software project over time, we
obtain the evolution history of a software system. Broadly classified,
there are three types of evolution histories (see Table 3.1): (i) the release
history, (ii) the revision history, and the (iii) the project history.
The release history contains the software artifacts that are released at
regular intervals in the project. The revision history is composed of
the version control logs and issue/defect records. The project history is
made up of the messages (e.g. email, chat logs), project documentation
as well as process information.
The software artifacts from the release history (specifically binaries and
source files) offer a direct evolutionary view into the size, structure and
41