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?.