Verification of results in software maintenance through external replication

Empirical studies carried out to help understand the problems of software maintenance are widely held to be of value. A view perhaps less widely recognised within the software engineering domain is that experiments should be replicated both internally and externally to validate the results and build up a cohesive body of knowledge. This paper presents the external replication findings of an experiment which tested the benefits to maintenance of using modular code against nonmodular (monolithic) code. The results of our replication were strikingly different from those of the original which showed that a modular program could be maintained significantly faster than an equivalent monolithic version. An inductive analysis, undertaken to investigate the reasons for this, uncovered evidence of an ability effect and the suggestion that the experiment may have been too artificial