A Software Requirements Change Source Taxonomy

Requirements changes during software development pose a risk to cost, schedule and quality while at the same time providing an opportunity to add value. Provision of a generic change source taxonomy which makes the distinction between factors contributing to requirements uncertainty and events that trigger change will support requirements change risk visibility, and also facilitate richer recording of change data. In this paper we present a collaborative study to investigate and support the management of software requirements volatility within the development lifecycle. Previously published change `causes' are elicited from the literature, consolidated using expert knowledge and classified using card sorting. The resulting change trigger taxonomy constructs were initially validated using a small set of requirements change data, and deemed sufficient and practical as a means to collect common requirements change source statistics across multiple projects.