Linköping Studies in Science and Technology
Dissertation No. 526

A Systematic Approach for Prioritizing
Software Requirements

Joachim Karlsson

Akademisk avhandling

som för avläggande av teknologie doktorsexamen vid Linköpings universitet kommer att offentligt försvaras i seminarierum Planck, Fysikhuset, Linköpings universitet, fredagen den 15 maj 1998, kl 14.15.

ABSTRACT

In most commercial development projects, there are more candidate requirements subject to implementation than available time and resources allow for. A carefully chosen set of requirements must therefore be selected for implementation. A systematic approach for prioritizing candidate requirements is a very useful means to provide necessary and useful input for the crucial selection decision.

This thesis provides results from the development and applications of different approaches for prioritizing requirements in close collaboration with Ericsson Radio Systems AB. A pairwise comparison approach for prioritizing requirements according to multiple criteria has been developed and applied. To overcome the high number of comparisons that the approach often required in projects with many requirements, different candidate approaches have been investigated and applied for reducing the required effort. An approach for managing requirement interdependencies and their implications for the prioritizing approach has been developed. A support tool packaging the prioritizing approach and automating much of the manual work in the approach has been developed and evaluated in practice.

Qualitative results indicate that the proposed approach is an effective means for selecting among candidate requirements, for allocating resources to them and for negotiating requirements. The approach further enables knowledge transfer and visualization, helps to establish consensus among project members and creates a good basis for decisions. Quantitative results indicate that the requirements actually selected for implementation have a profound impact on the final product. In several projects where requirements were prioritized according to the criteria value for customer and cost of implementation, implementing the requirements which optimize the relation of value for customer to cost of implementation would reduce the development cost and development time. Software systems with substantially the same value for customer can consequently be delivered with a reduction in cost and lead-time when the proposed prioritizing approach is deployed carefully.

Supported by Ericsson Radio Systems AB, the Swedish National Board for Industrial and Technical Development, Proj: 9303280-2 and the Industry Research School financed by KK-Stiftelsen under contract 199710480.

Department of Computer and Information Science
Linköping University
S-581 83 Linköping

ISBN 91-7219-184-8 ISSN 0345-7524