Types of Case Units (and Their Logic)

Types of Case Units (and their Logic)

Learning Objectives

  • Analyze the logic for whether a case unit fits the “object” or “process” category.
  • Survey the varying types of units that can be chosen for case study (in Figure 9). 
  • Familiarize yourself with the temporal characteristics that make a case unit either “diachronic” or “synchronic.” 
  • Contemplate why initial decisions about case unit temporality can have important consequences for the research design, potentially shifting the study closer to “history.”

Choosing “Object” versus “Process” Units

We learned in Module 4 that almost anything can serve as a case so long as the researcher sets clear boundaries for it and devises a plan to analyze it for social meaning. Punch (2014) summarizes that the case can be “an individual, or a role, or a small group, or an organization, or a community, or a nation. It could also be a decision, or a policy, or a process, or an incident or event of some sort, and there are other possibilities as well” (p. 121). Readers will notice that certain units are more spatial in nature, and hence more easily captured as “objects,” while others are more temporal in nature, and more easily captured as “processes.” If we consider, for example, the study of a local government decision, we may find that a process-framework fits better than a spatial one. Two reasons for this are as follows: 

  1. The phenomenon itself is fluid, undergoing (or having undergone) phases of change. 
  2. The compelling aspects of the phenomenon are these phases of change – not the spatial-material contexts in which they occur.  

In this situation, the researcher may determine that the phenomenon is best characterized as a process with at least some identifiable phases of change (indeed, the word “process” implies that there is some structural order or sequence to the change). The case unit, therefore, is defined predominantly in terms of temporal boundaries, with the spatial context occupying a secondary role. While it is true that this process occurs in a real-world setting, and has some spatial characteristics as a result, these are largely secondary in nature to the temporal/process characteristics. For example, in the case of the evolving government decision, it is less important to think about the myriad venues in which the decision-makers perform their daily activity than to pay attention to the phase-change of the decision-making itself (e.g., the shift from open-council debate to council voting; from voting to mayoral politics; from politics to municipal affairs, and so forth).  


FIGURE 9: Common Case Units 


Pasted Image


Studying across or within Time

There is another important level at which case study practitioners contemplate time, and that is temporal bracketing (Gerring, 2007, pp. 27-18; Abbott, 2001, pp. 129-60; Sandelowski, 1999). Social scientists use the terms “diachronic” and “synchronic” to distinguish the way in which they compartmentalize time in their research. A diachronic case study is one that focuses on a bracketed time period (from dates X to Y) and attempts to examine the evolution of the case within that period. A synchronic case study, by contrast, fixates on a single instance and examines the case for its social or contextual variation at that instance (Gerring, 2007, pp. 27-28). Remember that these terms refer to the temporal bounding of the cases themselves, rather than the case status as an objects or processes. A social group or institution can be bracketed diachronically just as well as a programmatic process.

To understand the diachronic/synchronic distinction more clearly, consider the research of anthropologist Ann Stahl, who investigated how ethnic style varied in Central Ghana from the 18th century to the present. She chose a diachronic approach because she felt that previous synchronic studies (focused on fixed instances in time) created a false sense of permanence for ethnic identity and projected this permanence into the past. Her goal, therefore, was to “explore temporal change in ethnic styles” and “locate this variability in historic context” (1991, p. 251). In contrast to Stahl’s study, consider the synchronic research of a Belgian political science team in 2006: Cline Teney and her colleagues examined the ethnic minority voting patterns of a single election cycle by focusing on variations within the 2006 cycle, looking at three city district polling outcomes (Teney, Jacobs, Rea, & Delwit, 2010).

Is it Case Study or History?

 The decision about whether to pursue diachronic-versus-synchronic research could prompt other important design questions: for example, will the bracketing be contemporary or in the past? If in the past, does it involve a near-term or distant past? If it involves a distant past, will the researcher need to draw skills from history to perform data collection and analysis? In today’s academic world, it is not uncommon for social science to incorporate some aspects of historical research. Cultural anthropology is particularly apt to do this because of its scope (current and past cultures) and overlapping subfields with cultural history and cultural studies. Sociology intermingles with history when the goal is to trace developments before the present or use past instances to shed light on the present. Wieviorka discerns that in sociology, the bulk of case studies have been “divided between sociological and historical approaches,” where the latter aims “to make a diagnosis in history or to exemplify a historical hypothesis” (1992, pp. 161-62).


Some methodologists invent artificial boundaries between history and case study based on their sources of data. Yin, for example, proposes three distinct categories: history, historical case study, and contemporary case study (just called “case study”). He reasons that “the distinctive contribution of historical method is in dealing with the ‘dead’ past – that is, when no relevant persons are alive to report, even retrospectively, what occurred and when an investigator must rely on primary documents, secondary documents, and cultural and physical artifacts as the main source of evidence” (2009, p. 11). Yin sees historical case study as the method for investigating a recently past phenomenon, relying on both archival documents and the retrospective testimonies of individuals still living (i.e., oral history). Case study in the contemporary sense, meanwhile, relies on direct (field-level) observation and interviews with individuals closely familiar with the contemporary cases (the researcher is free to add other sources as needed).


The problem with Yin’s artificial categories is twofold. First, he ignores the changing nature of history as a discipline, which has grown to incorporate data sources previously thought to belong only to case study. Since the 1980s, a great many historians have taken “the narrativist turn” in the human sciences and have come to see social actors as “narrative builders”; authors of narrative constructs in the form of archival documents, artifacts, and oral testimonies (Kuukkanen, 2012; Hyvarinen, 2010; Kreiswirth, 2000; 1992). As a result of this shift, historians today are more likely to treat “history” as the telling of stories about other stories, where no single data source holds superiority. Hence, multiple data sources have become the norm. The second problem with Yin’s outlook is that practitioners of “historical case study” rarely define research by data sources alone. Rather, they apply historiographic (or epistemological) arguments about why a case-based approach is appropriate for analyzing past issues and connecting them with current issues (Kinzel, 2015; Abbott, 2001). The whole point of the historical case study is to arrive at an historical claim, and this to some degree involves historiography (Wieviorka, 1992, pp. 161-62).



Abbott, A. (2001). Time Matters: On Theory and Method (pp. 129-82). Chicago: Univ. of Chicago Press. 

Hyvarinen, M. (2010). Revisiting the narrative turns. Life Writing 7 (1): 69-82. 

Kinzel, K. (2015). Narrative and evidence. How can case studies from the history of science support claims in the philosophy of science. Studies in the History & Philosophy of Science, Part A 49: 48-57. 

Kuukkanen, J. (2012). The missing narrativist turn in the historiography of science. History and Theory 51 (3): 340-63. 

Kreiswirth, M. (1992). Trusting the tale: the narrativist turn in the human sciences. New Literary History 23 (3): 629-57. 

Kreiswirth, M. (2000). Merely telling stories? Narrative and knowledge in the human sciences. Poetics Today 21 (2): 293-318.

Punch, P. K. (2014). Introduction to Social Research: Qualitative and Quantitative Approaches (3rd ed.). Thousand Oaks: SAGE. 

Sandelowski, M. (1999). Focus on qualitative methods: time and qualitative research. Research in Nursing & Health 22 (1): 79-87. 

Stahl, A. B. (1991). Ethnic styles and ethnic boundaries: a diachronic case study from West-Central Ghana. Ethnohistory 38 (3): 250-75.  

Snow, D. A., & Trom, D. (2002). The case study and the study of social movements. In B. Klandermans & S. Staggenborg (Eds.), Methods of Social Movement Research. Social Movements, Protests, and Contention, Vol. 16 (pp. 146-72). Minneapolis: Univ. Minnesota Press. 

Teney, C., Jacobs, D., Rea, A., & Delwit, P. (2010). Ethnic voting in Brussels: voting patterns among ethnic minorities in Brussels (Belgium) during the 2006 local elections. Acta Politica 45 (3): 273-97.  

Thomas, G. (2011). A typology for the case study in social science following a review of definition, discourse, and structure. Qualitative Inquiry 17 (6): 511-21. 

Yin, R. K. (2009). Case Study Research: Design and Methods (4th ed.). Thousand Oaks: SAGE. 


Viewed 1,606 times