Characterising requirements volatility: An empirical case study

Requirements volatility is inevitable and is still perceived as a problem in software development projects, particularly in situations where competitive strategies and technologies are evolving rapidly. Investigating the characteristics of requirements volatility and its consequences is important as it can lead to the development of more effective strategies for managing requirements volatility. This paper describes the results of an industrial case study investigation into requirements volatility during the life cycle of a software development project. The characteristics of requirements volatility are identified using a simple mechanism that can be applied when analysing requirements change requests. In our previous work we developed a classification of requirements change and identified three main elements: Change Types, Reason Category, and Sources of Change. The results presented in this paper broaden that work in threefold: 1) to characterise the nature of requirements volatility, 2) to demonstrate that the classification enables us to characterise the nature of requirements volatility, in this case on a different software project, and 3) to visualise the extent of requirements volatility throughout the software development life cycle. This paper discusses the implications of the classification to better understand the requirements volatility problem.