Requirement prioritization is important in software development for several reasons. First and foremost, software products are created to fulfill some intended purpose characterized in terms of business goals or mission objectives. Typically these “objectives have implied quality concerns,” which have significant influence on the architecture of a system; “for instance, a business goal to maintain market reputation [may] correspond to creating products that are highly secure and reliable.” These quality attributes or nonfunctional requirements must be addressed early in the development life cycle, ahead of any function or feature development. “If ignored or not fully understood,” there is a risk of “creating a system that may not be fit for its intended purpose.” Second, in order to maximize the delivery of value, requirements that have significant benefit to the stakeholders must be implemented ahead of other functional requirements. Third, since projects have limited resources, requirements that are critical for creating a viable product must be implemented ahead of those that may be nice to have.

In this systematic mapping study, Thakurta surveys different techniques for requirement prioritization that have been used to address these needs. Based on the survey, he identifies current research themes and answers four research questions. The themes include objectives of requirement prioritization, requirement prioritization artifacts, theoretical foundations and design characteristics of these requirement prioritization artifacts, and the factors that influence the overall requirement prioritization process. The predominant objectives behind requirement prioritization are demonstrating requirement priority, requirement selection, requirement categorization, and requirement value assessment. Requirement prioritization artifacts can be broadly classified as more abstract and conceptual (such as requirement prioritization models and methods) or physical (such as a requirement prioritization tool). These artifacts are either described argumentatively (based on some logic) or are based on established theoretical propositions. The process of prioritization can be influenced by factors that are internal to a project or those that are external.

Requirement prioritization continues to be an ad hoc and intuitive process with prioritization values more hypothetical than grounded in any theory, creating a strong demand for requirement prioritization methods that are trustworthy. There are significant gaps, which are likely to receive attention in the future. These include giving due consideration to external factors, such as business goals and stakeholder preferences; designing requirement prioritization artifacts that adhere to multiple objectives; the conceptualization of stochastic parameters that can assume a range of values to represent requirement priority values; and the development and selection of requirement specification artifacts using some kind of a decision analysis framework. This survey provides a useful overview of the current state of the art to practicing requirements engineers who are constantly struggling with the issue of prioritizing requirements and to researchers who are interested in a roadmap for future research on this topic.