Michelle K McGinn. Encyclopedia of Case Study Research. Editor: Albert J Mills, Gabrielle Durepos, Elden Wiebe. Sage Publications, 2010.

Depth of data refers to the detail, richness, comprehensiveness, and explanative power of the data supporting a case study. Increased depth of data positively affects the perceived credibility and applicability (or generalizability) of a case study. At the same time, this increased depth can also raise ethical challenges regarding the protection of privacy and confidentiality.

Depth and Breadth of Data

Characteristically, case study research draws from an extensive and varied array of data resources to bring depth of understanding about a well-defined, narrowly focused, and clearly bounded case. Researchers may face a tradeoff between depth and breadth in gathering and presenting data for a case study. Although it is essential for case study researchers to seek out extensive evidence to develop a comprehensive understanding of the case, choices must be made about how much of that evidence can be presented directly in any case study report. Researchers must consider publishers’ requirements and readers’ needs in judging the amount and depth of data that can be presented.

The challenges of gathering and presenting sufficient depth of data in a case study report are particularly acute for collective and comparative case study research, where there is a need to consider information from multiple cases. It is not uncommon for cross-case studies to be criticized as thin, reflecting insufficient depth about any individual case. At the same time, collective and comparative case studies are valuable because the emphasis on similarities and differences across cases can provide breadth of understanding about the phenomenon of interest that extends beyond one individual case.

Depth of Data Affects Credibility and Applicability

Case study researchers establish depth of data through triangulation and thick description, both strategies that contribute to credibility of data.

Through triangulation, comparing and contrasting across multiple data resources, case study researchers uncover consistencies and inconsistencies, thereby providing evidence from multiple perspectives and incorporating assessments about the veracity of the evidence presented. In this way, researchers can build robust understandings about the case under investigation that are likely to be judged as credible.

Case study reports typically include thick description; that is, they go beyond mere facts and surface features of the case to include details, context, circumstances, meanings, significance, motivations, emotions, social relations, history, and other such descriptive and interpretive elements of the case. Thick description that is well supported by evidence will be perceived as credible. This level of detail brings the case to life for readers so that they are more likely to make positive judgments about the credibility of the case and its potential applicability in other contexts.

Thick description in a case study report provides extensive information that readers can use to understand the case. At the same time, this thick description provides an evidence base for readers to make comparisons with other situations and make predictions about how well the conclusions about the reported case might apply in these new situations. Without thick description, readers are left with insufficient information to understand the reported case or to apply that case to other situations, thereby substantively undermining the value of the case study.

Depth of Data Affects Privacy and Confidentiality

The depth of data that case study researchers seek in their efforts to understand a case leads to highly identifiable research records. Case study researchers need to seek permission or consent from relevant people associated with the case in order to access the extensive data required to generate understandings about the case. Beyond initial data access, researchers also need to think carefully about how to present this depth of data without sacrificing privacy and confidentiality commitments to the people associated with the case.

Dena Davis describes the paradox of writing case studies in the field of bioethics. As she indicates, the kinds of details that make case studies identifiable are frequently the very same details that make those case studies informative and worthwhile. Disguising details about age, gender, nationality, and other important biographical details to protect identities in case studies may confound key issues in the case and undermine possibilities for readers to develop their own understandings that go beyond the author’s original interpretation.

Researchers may need to consult with participants who could be identified in a case study or with stakeholders associated with the place, organization, or object under investigation to inform their choices about the appropriate balance between identifying details and confidentiality provisions in a specific case. In some situations, it may be appropriate to provide clearly identifiable information as part of the case study, as is common in journalism, oral history, public policy research, and other forms of scholarship. In other situations, it may be appropriate to forego certain statements or conclusions in case study research when those claims can be substantiated only with identifying details that would lead to risks or harms to someone associated with the case, and the potential benefits that could accrue from including those details provide insufficient justification for that level of risk or harm.

Critical Summary

Case study researchers strive for depth of data to generate substantive evidence and rich understandings about the cases they study. The depth of data in a given research study may need to be counter-balanced with the desired breadth of data, especially for comparative and collective case studies. Triangulation and thick description are two important considerations in achieving depth of data. Increased depth of data contributes to the resulting credibility of a case study and may affect its applicability (or generalizability). However, there are ethical challenges associated with increasing depth of data in case study research. Site access stipulations, research permissions, and consent processes affect researchers’ access to data, and privacy and confidentiality provisions influence researchers’ decisions about how to protect or divulge identifying information that contributes to the depth of data.