Björn Regnell

Using Students as Subjects—A Comparative Study ofStudents and Professionals in Lead-Time Impact Assessment

In many studiesin software engineering students are used instead of professionalsoftware developers, although the objective is to draw conclusionsvalid for professional software developers. This paper presentsa study where the difference between the two groups is evaluated.People from the two groups have individually carried out a non-trivialsoftware engineering judgement task involving the assessmentof how ten different factors affect the lead-time of softwaredevelopment projects. It is found that the differences are onlyminor, and it is concluded that software engineering studentsmay be used instead of professional software developers undercertain conditions. These conditions are identified and describedbased on generally accepted criteria for validity evaluationof empirical studies.

Case Study Research in Software Engineering: Guidelines and Examples

Based on their own experiences of in-depth case studies of software projects in international corporations, in this bookthe authors present detailed practical guidelines on the preparation, conduct, design and reporting of case studies of software engineering. This is the first software engineering specific book on thecase study research method.

An evaluation of methods for prioritizing software requirements

This article describes an evaluation of six different methods for prioritizing software requirements. Based on the quality requirements for a telephony system, the authors individually used all six methods on separate occasions to prioritize the requirements. The methods were then characterized according to a number of criteria from a users perspective. We found the analytic hierarchy process to be the most promising method, although it may be problematic to scale-up. In an industrial follow-up study we used the analytic hierarchy process to further investigate its applicability. We found that the process is demanding but worth the effort because of its ability to provide reliable results, promote knowledge transfer and create consensus among project members.

An industrial survey of requirements interdependencies in software product release planning

The task of finding an optimal selection of requirements for the next release of a software system is difficult as requirements may depend on each other in complex ways. The paper presents the results from an in-depth study of the interdependencies within 5 distinct sets of requirements, each including 20 high-priority requirements of 5 distinct products from 5 different companies. The results show that: (1) roughly 20% of the requirements are responsible for 75% of the interdependencies; (2) only a few requirements are singular; (3) customer-specific bespoke development tend to include more functionality- related dependencies whereas market-driven product development have an emphasis on value-related dependencies. Several strategies for reducing the effort needed for identifying and managing interdependencies are outlined. A technique for visualization of interdependencies with the aim of supporting release planning is also discussed. The complexity of requirements interdependency analysis is studied in relation to metrics of requirements coupling. Finally, a number of issues for further research are identified.

An industrial case study on distributed prioritisation in market-driven requirements engineering for packaged software

When developing packaged software, which is sold ‘off-the-shelf’ on a worldwide marketplace, it is essential to collect needs and opportunities from different market segments and use this information in the prioritisation of requirements for the next software release. This paper presents an industrial case study where a distributed prioritisation process is proposed, observed and evaluated. The stakeholders in the requirements prioritisation process include marketing offices distributed around the world. A major objective of the distributed prioritisation is to gather and highlight the differences and similarities in the requirement priorities of the different market segments. The evaluation through questionnaires shows that the stakeholders found the process useful. The paper also presents novel approaches to visualise the priority distribution among stakeholders, together with measures on disagreement and satisfaction. Product management found the proposed charts valuable as decision support when selecting requirements for the next release, as they revealed unforeseen differences among stakeholder priorities. Conclusions on stakeholder tactics are provided and issues of further research are identified, including ways of addressing identified challenges.

Requirements engineering challenges in market-driven software development - An interview study with practitioners

Requirements engineering for market-driven software development entails special challenges. This paper presents results from an empirical study that investigates these challenges, taking a qualitative approach using interviews with fourteen employees at eight software companies and a focus group meeting with practitioners. The objective of the study is to increase the understanding of the area of market-driven requirements engineering and provide suggestions for future research by describing encountered challenges. A number of challenging issues were found, including bridging communication gaps between marketing and development, selecting the right level of process support, basing the release plan on uncertain estimates, and managing the constant flow of requirements.

Improving the use case driven approach to requirements engineering

The paper presents the idea of usage oriented requirements engineering, an extension of use case driven analysis. The main objective is to achieve a requirements engineering process resulting in a model which captures both functional requirements and system usage aspects in a comprehensive manner. The paper presents the basic concepts and the process of usage oriented requirements engineering, and the synthesized usage model resulting from this process. The role of this model in system development, and its potential applications are also discussed.

Market-Driven Requirements Engineering for Software Products

An increasing part of software development is devoted to products that are offered to an open market with many customers. Market-driven development imposes special challenges for the requirements engineering process. This chapter provides an overview of the special characteristics of market-driven requirements engineering and describes the most important challenges of the area. Key elements of market-driven requirements engineering processes are presented together with a definition of process quality. Requirements state models and requirements repositories are also described and examples of typical solutions to progress tracking and data management are provided. The difficult problem of release planning is also discussed and an industrial example of a release planning process is given.

A hierarchical use case model with graphical representation

Use case modelling is gaining increasing interest in computer-based systems engineering, especially in the earliest stages of system development, where requirements are elicited, documented and validated. The paper presents a conceptual framework for use case modelling and a new use case model with graphical representation, including support for different abstraction levels and mechanisms for managing large use case models. Current application of use cases in requirements engineering is discussed, as well as ontological and methodological issues related to use case modelling.

Are the Perspectives Really Different? – FurtherExperimentation on Scenario-Based Reading of Requirements

Perspective-BasedReading (PBR) is a scenario-based inspection technique whereseveral reviewers read a document from different perspectives(e.g. user, designer, tester). The reading is made accordingto a special scenario, specific for each perspective. The basicassumption behind PBR is that the perspectives find differentdefects and a combination of several perspectives detects moredefects compared to the same amount of reading with a singleperspective. This paper presents a study which analyses the differencesin perspectives. The study is a partial replication of previousstudies. It is conducted in an academic environment using graduatestudents as subjects. Each perspective applies a specific modellingtechnique: use case modelling for the user perspective, equivalencepartitioning for the tester perspective and structured analysisfor the design perspective. A total of 30 subjects were dividedinto 3 groups, giving 10 subjects per perspective. The analysisresults show that (1) there is no significant difference amongthe three perspectives in terms of defect detection rate andnumber of defects found per hour, (2) there is no significantdifference in the defect coverage of the three perspectives,and (3) a simulation study shows that 30 subjects is enough todetect relatively small perspective differences with the chosenstatistical test. The results suggest that a combination of multipleperspectives may not give higher coverage of the defects comparedto single-perspective reading, but further studies are neededto increase the understanding of perspective difference.