The impact of software design structure on product maintenance costs and measurement of economic benefits of product redesign

Abstract

This paper reports results of an empirical study that aimed to demonstrate the link between software product design structure and engineers' effort to perform a code modification in the context of a corrective maintenance task. First, this paper reviews the current state of the art in engineering economics of the maintenance phase of software lifecycle. Secondly, a measure of software product complexity suitable to assess maintainability of a software system is developed. This measure is used to analyze the design structure change that happened between two versions of a mature software product. The product selected for this study underwent a significant re-design between two studied versions. Thirdly, an experiment is designed to measure the effort engineers spend designing a code modification associated with a corrective change request. These effort measurements are used to demonstrate the effect of product design complexity on engineers' productivity. It is asserted in the paper that engineer's productivity improvements have a significant economic value and can be used to justify investments into re-design of an existing software product.