Qualitative research methods were developed in the social sciences to enable researchers to study social and cultural phenomena and are designed to help researchers understand people and the social and cultural contexts within which they live (Denzin and Lincoln 2011). The goal of understanding a phenomenon from the point of view of the participants and its particular social and institutional context is largely lost when textual data are quantified. Taylor and Bogdan (1984) point out that qualitative research methods were designed mostly by educational researchers and other social scientists to study the complexities of human behavior (e.g., motivation, communication, difficulties in understanding). According to these authors, human behavior is clearly a phenomenon that, due to its complexity, requires qualitative methods to be fully understood, since much of human behavior cannot be adequately described and explained through statistics and other quantitative methods. Examples of qualitative methods are action research, case study research, ethnography, and grounded theory. Qualitative data sources include observation and participant observation (fieldwork), interviews and questionnaires, documents and texts, and the researcher’s impressions and reactions.

Many in the software industry recognize that software development also presents a number of unique management and organizational issues that need to be addressed and solved in order for the field to progress. And this situation has led to studies related not only to software engineering technical issues, but also to non-technical issues as well as to the intersection between the technical and non-technical aspects. Complex software engineering issues can be difficult to study using a purely quantitative approach. The reasons for this include typically small sample sizes, the expense of controlled experiments with human subjects, and the need for preliminary support before hypothesis testing can begin. Alternatively, qualitative studies can generate well-grounded hypotheses and findings that incorporate the complexity of the phenomenon under study. They also offer richer explanations and new areas for future study. They are also appropriate when variables are not defined or quantified and there is little prior theoretical or empirical work.

Lastly, a principal advantage of using qualitative methods is that they force the researcher to delve into the complexity of the problem rather than abstract it away, and the results can be more informative. Thus, since software engineering involves complex human behavior in an environment and circumstances that are to date not well developed theoretically or empirically and the phenomenon requires rich explanation in order to develop constructs and hypothesis, we need to raise the awareness regarding qualitative research in this field.

For this reason, we solicited submissions for this Special Issue on the topic of “Qualitative Research in Software Engineering”. This special issue was meant to overcome some of the methodological challenges by providing software engineering researchers with good examples of the state of the art in the application of qualitative research methods to software engineering problems. We hoped to include articles that could illustrate good flexible research designs, and how methodological challenges in software engineering research can be addressed.

In this special issue we have gathered four papers that present innovative ideas on how to cope with the growing complexity of effectively researching software engineering phenomena using qualitative approaches. We received papers from around the world, 24 in total. Each paper was reviewed by at least three expert referees. The guest editors would like to thank all the reviewers and authors of submitted papers to this Special Issue.

The four papers of this Special Issue employ a variety of qualitative research methods to address a variety of software engineering phenomena. Two of the papers, those by Prechelt and Oezbek and by Adolph et al., employ grounded theory, although they both tailor and interpret traditional grounded theory techniques for the particular needs of software engineering researchers. Thus, they provide a much-needed resource for researchers in our field who are struggling with adapting grounded theory based on resources written for researchers in education and the social sciences. Sim and Alspaugh’s paper on their “war story” study of requirements engineering is another example of tailoring a traditional qualitative research method (interviews) to the context of studying software engineering phenomena. Another twist in a well-known research approach, the case study, is presented in McLeod et al., who present a detailed explanation and rationale for a “longitudinal” case study methodology. Synopses of these four papers follow.

Prechelt and Oezbek present a narrative about their multiple attempts to study the phenomenon of software process improvement in open source software development. They found this subject very difficult to address, and tried a number of well-reasoned approaches to the problem. In addition to the approach that was finally successful, an adaptation of grounded theory, their article provides a rare exposition of the failings of several other methodological approaches to this problem.

McLeod et al. give a detailed descriptive and prescriptive treatment of a type of case study approach, the longitudinal case study, which is particularly well suited for exploring complex software development phenomena. In particular, the authors found this approach useful in understanding the multiple factors, including time, that interacted to effect the outcomes of the project being studied.

Sim and Alspaugh provide deep insights and five valuable recommendations related to analyzing data from “war stories” interviews. Standard quantitative analysis techniques, which broke down the stories into smaller “facts”, led the authors to lose the structure of each story. On the other hand, analysis using techniques from the humanities, along with concepts such as methodical vs. amethodical perspectives, enabled new useful insights.

Adolph, et al., present their own experiences of implementing Glaserian grounded theory. Although the method is time consuming and tedious, they find it to be an effective tool for software engineering research. Based on their own case of applying grounded theory in a software engineering context they provide insightful lessons learned and useful guidelines for how to interpret the canons of classical grounded theory literature.

It is our hope that this Special Issue will serve as a resource for software engineering researchers, through its detailed examples of how these authors tailored and applied qualitative research methods to contribute to the body of knowledge in our field. We also sincerely desire for this issue, and for the growing body of literature describing qualitative research in software engineering, to motivate the research community to employ qualitative methods, alone or in mixed methods designs, to more fully study the complexities of software engineering. We believe that progress in our field requires full consideration of human behavior within software development environments, and that understanding the complexities of human behavior requires that researchers go beyond the limitations of quantification and statistical analysis. Qualitative research methods have been found, in many other fields, to be critical to grasping and understanding the phenomena in which humans play a role. We are pleased to present this Special Issue as a contribution towards the continuing need for qualitative research in software engineering.