Case Studies (College Board AP® Psychology): Revision Note

Case studies

• A case study is a detailed, in-depth investigation of an individual or small group

• Case studies typically focus on individuals who have undergone a rare or unique experience, or who present with an unusual condition, e.g.

  • A patient who had a hemispherectomy to treat severe epilepsy

  • An individual presenting with dissociative identity disorder

  • A person who suffered significant brain damage following an accident

• Case studies are a non-experimental methodology as there is no manipulation of an IV

Data collection in case studies

• Case studies commonly use multiple methods to collect data, which means they can generate both qualitative and quantitative data:

  • Qualitative data is collected via interviews, observations, and open-ended questions

    • This captures the subjective, individual experience of the participant in rich detail

  • Quantitative data is collected via memory tests, IQ tests, neuroimaging, and closed questions on questionnaires

    • This produces numerical scores that can be analyzed statistically

• When a case study uses more than one method of data collection, this is known as triangulation:

  • Triangulation of method

    • Using more than one data collection method in the same study (e.g. interviews plus observations plus memory tests)

  • Triangulation of data

    • Generating more than one type of data in the same study (e.g. both qualitative and quantitative data)

  • Triangulation of research

    • Using more than one researcher to collect or analyze data in the same study

• Triangulation strengthens the validity of findings by cross-referencing data from multiple sources

  • If different methods produce consistent conclusions, confidence in those conclusions is increased

Longitudinal design in case studies

• Most case studies are longitudinal

  • This is where the participant's experience, behavior, or condition is tracked and measured over an extended period of time

  • A case study may take weeks, months, or even years to complete

• Longitudinal design is a strength because it allows researchers to observe changes and developments in the participant over time, producing a richer and more complete picture of their experience

• However, it also increases the risk that the researcher becomes too closely involved with the participant over time, which can compromise objectivity and introduce bias

Example: the case of H.M.

• H.M. is one of the most significant case studies in psychology

  • He underwent surgery to remove his hippocampus as a treatment for severe epilepsy, which resulted in a profound inability to form new long-term memories

• Qualitative data was collected via interviews and observations of H.M. both at home and in clinical settings

• Quantitative data was collected via memory tests, IQ tests, and neuroimaging of his brain

• The case study was longitudinal — H.M. was studied closely for decades

• By studying H.M. in such depth over time, researchers were able to conclude that the hippocampus plays an essential role in the formation of new long-term memories

• This illustrates how case studies can generate insights into typical human functioning by studying individuals with atypical conditions

Evaluation of case studies

Strengths

• Case studies provide rich, detailed, in-depth data that is high in ecological validity

  • Because data is collected in real-world contexts using multiple methods, the findings reflect the genuine complexity of the participant's experience

• Studying individuals with rare or unusual conditions allows researchers to draw conclusions about typical human functioning that would be impossible to investigate experimentally

  • E.g. the case of H.M. revealed the essential role of the hippocampus in memory formation

• Triangulation strengthens the validity of findings

  • Using multiple methods and data types allows researchers to cross-reference conclusions and increases confidence in the accuracy of the results

Limitations

• The findings from a case study represent only the individual or small group being studied

  • As the sample is so small and often atypical, the findings cannot be generalized to wider populations

  • This limits the external validity of the research

• The researcher may lose objectivity due to the close and often extended relationship with the participant

  • Particularly in longitudinal case studies, the researcher may begin to identify with the participant

  • This introduces bias into their interpretation and reporting of the findings, reducing validity

• Self-report bias and social desirability bias are inherent limitations when interviews or questionnaires are used as data collection tools in case studies

  • Participants may give inaccurate accounts or respond in socially desirable ways

  • This reduces the validity of the findings