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Case Study 101

What is a case study?

The case study “can be defined as an intensive, holistic description and analysis of a single entity, phenomenon, or social unit. Case studies are particularistic, descriptive, and heuristic and rely heavily on inductive reasoning in handling multiple data sources” (Merriam, 1988, p. 16).

“A case study is an exploration of a “bounded system” or a case (or multiple cases) over time through detailed, in-depth data collection involving multiple sources of information rich in context” (Creswell, 1998, p. 61).

“A case study is an empirical inquiry that investigates a contemporary phenomenon within its real-life context” and “relies on multiple sources of evidence, with data needing to converge in a triangulating fashion” (Yin, 2003, pp. 13-14).

  • Despite their differences, all definitions highlight the “bounded”, singular nature of the case, the importance of context, the availability of multiple sources of information or perspectives on observations, and the in-depth nature of analysis.

What can be a case? (Lichtman, 2009; Merriam, 1998; Yin, 2003)

“A case study is conducted to shed light on a particular phenomenon, that is, a set of processes, events, individuals, or other things of interest to the researchers. … A phenomenon has many aspects, so researchers must select a focus for investigation. The focus is the aspect, or aspects, of the phenomenon on which data collection and analysis will concentrate” (Gall, Gall, & Borg, 1999, p. 292).

  • A case is “a phenomenon of some sort occurring in a bounded context (Miles & Huberman, 1994, p. 25, as cited in Merriam, 1998, p. 27).

What are the historical roots of case study? (Duff, 2007)

Psychology & Biology:

18th century: Tiedemann: in-depth scientific observation of physical and psychological changes in his infant.

19th century: Darwin: in-depth study of his son’s behaviour.

20th century: Piaget: in-depth study of the stages of development of his children.

Sociology & Anthropology:

20th century: Malinowski: case study of cultural communities in the Trobriand Islands.


20th century: Halliday: in-depth study of his son’s language development (use of language functions).

Case study research is also used in medicine, law, management, economics, business, policy, planning, history, journalism, and public administration.

How is case study employed in Applied Linguistics and SLA? (Duff, 2007)

Case study methodology was not mentioned in research methods books before the 1990s, despite its importance in the field. In 1978, Hatch made a great contribution by publishing a collection of SLA case studies. From the 90s onwards, many research methods books have started to include chapters on case study.

Themes and trends:

Studies of child language acquisition, bilingualism, and language loss

Natural-order studies and performance analysis

Individual differences: exceptionality, talented and untalented learners

Diaries, memoires, and (auto)biographies of linguistic experiences Identity, investments, and gender in language learning

Language learning, stabilization, fossilization, and loss

Pragmatic and sociolinguistic development

Mainstreamed ESL students: identity, representation, and positioning

Second language writing and academic discourse socialization

Online language development and use: Socialization into virtual communities

Bilingualism and biculturalism

Teachers as agents of linguistic and cultural socialization cellspacing="0" cellpadding="0" width="503" style="width:671px;"

What are the types of case study? (Hancock & Algozzine, 2006; Duff, 2007; Merriam, 1998; Stake, 1995; Yin, 2003)

How do we design and conduct a case study? (Duff, 2007; Hancock & Algozzine, 2006; Lichtman, 2009; Yin, 2003)

Research Objectives: see categorization of case study.

Research Questions:

Identify research problems.

Define your construct (e.g. critical period, identity, motivation/investment).

Come up with specific, answerable, relevant, interesting, and worthwhile questions.

Case selection aspects to consider:

What entity will constitute the case? (e.g. a teacher, a learner, a school)

What phenomenon within the case will be investigated? (e.g. measure of advanced proficiency)

Does it provide adequate learning opportunities?

Is it accessible and welcoming to our inquiry? Is it a unique or typical case?

Data Collection: multiple sources (based on Yin, 2003).

Data Analysis: the choice depends on the types of data and the theoretical constructs underlying the study.


What are the advantages of using a case study? (Duff, 2007; Merriam, 1998)

Rich description: holistic, in-depth analysis of a case in its natural context.

Triangulation: it allows for etic and emic perspectives and uses multiple data sources.

Potential for advancement of research: provides an opportunity for theory development and hypothesis testing.

Atypical cases: enables the investigation of unique or extreme cases.

Longitudinal research: by undertaking an in-depth study of one or a few subjects, it makes it more feasible to examine the phenomenon using a longitudinal design.

What are the limitations of using case study? (Duff, 2007; Merriam, 1998)

Feasibility: can be a time, effort, and money consuming method of research.

Attrition: dropping out of the study for any reason could be problematic for the researcher. In single longitudinal case studies attrition becomes a serious drawback.

Research ethics: with such detailed description and analysis of an individual, the identity of the participant maybe difficult to conceal.

Unique or extreme cases: the use of such cases as the primary data source for the construction of theories or models for “typical” behaviour is criticized by many researchers. cellspacing="0" cellpadding="0" width="509" style="width:678px;"

What are the validity issues of case study? (Duff, 2007; Gall, Gall, & Borg, 1999; Yin, 2003)

What are the misconceptions of case study? (Duff, 2007)

Quan & Qual: often misperceived as being only a qualitative method. Although cases are generally associated with qualitative research, many are analyzed quantitatively as well. The case study may also be a qualitative component in a larger quantitative study as a program evaluation.

Confusion with ethnography: while a case study focuses on the behaviours or attributes of learner(s) or entities, ethnography aims to understand the cultural basis for behaviours, values, and structures of social groups.

Example of a study with the use of method

Ioup, G., Boustagui, E., El Tigi, M., & Moselle, M. (1994). Reexamining the critical period hypothesis: A case study of successful adult SLA in a naturalistic environment. Studies in Second Language Acquisition, 16, 73-98.

Focus: an exploratory mixed methods single case study that examines adult learner’s successful L2 acquisition in a naturalistic environment.

Participant: Julie, a female adult L1 English speaker, who achieved native-like competency in Egyptian Arabic as L2 while learning it without formal instruction after immigrating to Egypt at the age of 21, i.e. after the close of the critical period.

Purpose: to identify to what extent Julie’s L2 competence matches that of native speakers and to provide a possible explanation of her successful L2 acquisition in a naturalistic environment.

Data sources (qualitative and quantitative):

Interviews (information about Julie’s L2 learning practices and experiences).

Extensive testing of L2 competence (tasks: speech production, grammaticality judgment, translation into L2, accent recognition etc).

Major findings:

Julie performed surprisingly well on all tasks, and her Egyptian Arabic competence is comparable to that of native speakers.

Julie’s performance is very similar to the native-like performance of an Egyptian Arabic learner who was receiving formal L2 instruction for many years.

Possible explanation of Julie’s success in L2 acquisition at the adult age, i.e. after the close of the critical period: in addition to consciousness of language learning, she might be an exceptional L2 learner possessing an aptitude for L2.

Theoretical implications: reexamination of the critical period hypothesis: “If there is a critical period for language acquisition, it is because some neurocognitive change has occurred in the brain as it matured; if there are exceptions to the critical period, this change does not happen in the usual way” (Ioup et al., 1994, p. 93), and more research is needed to describe the nature of this phenomenon.

Recommended Sources

Duff, P. (2007). Case study research in applied linguistics. Mahwah, NJ: Erlbaum.

Gall, J. P., Gall, M. D., & Borg, W. R. (1999). Applying educational research: A practical guide. New York: Longman.

Hancock, D. R., & Algozzine, R. (2006). Doing case study research: A practical guide for beginning researchers. New York: Teachers College Press.

Stake, R. E. (1995). The art of case study research. Thousand Oaks, CA: Sage.

Merriam, S. B. (1998). Qualitative research and case study applications in education. San Francisco: Jossey-Bass Publishers.

Yin, R. K. (2003). Case study research: Design and methods. Thousand Oaks, CA: Sage Publications.

Yin, R. K. (2006). Case study methods. In J. L. Green, G. Camilli, P. B. Elmore, A. Skukauskaite, & E. Grace (Eds.), Handbook of complementary methods in education research (pp. 111-122). Mahwah, NJ: Lawrence Erlbaum Associates.

(n.d.). Qualitative research: Case study guidelines. TESOL Quarterly, Retrieved from

Other References

Creswell, J (1998). Qualitative inquiry and research design: Choosing among five traditions. Thousand Oaks, CA: Sage.

Faltis, C. (1997). Case study methods in researching language and education. In N. Hornberger & D. Corson (Eds.), Research methods in language and education (pp. 145-152). Dordrecht, Netherlands: Kluwer.

Ioup, G., Boustagui, E., El Tigi, M., & Moselle, M. (1994). Reexamining the critical period hypothesis: A case study of successful adult SLA in a naturalistic environment. Studies in Second Language Acquisition, 16, 73-98.

Lichtman, M. (2009). Qualitative research in education: A user’s guide. Thousand Oaks, CA: Sage Publications.

Merriam, S. (1988). Case study research in education: A qualitative approach. San Francisco: Jossey-Bass.


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