It is the view of many computer scientists that the standard of
empirical software engineering research leaves scope for improvement.
However, there is also an increasing awareness in the software
engineering community that empirical studies are a vital aspect in the
process of improving methods and tools, for software development and
maintenance. This paper presents a review of the empirical work carried
out to date in the area of program comprehension and illustrates that
most of the evidence from these studies derives from lab-based
experiments, thus implying a degree of artificial control. The paper
argues that, in order to address the methodological shortfalls of the
experimental paradigm, more qualitative methods need to be applied to
accompany and support these quantitative studies, thus broadening the
sources of data and increasing the 'body of evidence'.