Allow researchers to examine individuals in great depth
Behaviour is explored in a way where researchers can explain the feelings of the individual around particular behaviours and issues
Data is often collected through interviews or observations, generating mostly qualitative data, but can be triangulated with methods that generate quantitative data also
Most case studies tend to be longitudinal i.e. a participant's experience/progress is tracked and measured (qualitatively and sometimes quantitatively) over time
The case of HM: qualitative data was obtained via interviews and observations; quantitative data was obtained via memory tests, IQ tests and MRI scanning of his brain
Results are not generalisable or representative due to (usually) only one person being the focus of the study
The researcher may be biased in their interpretation of the information
Often case studies rely on their participants having a good memory which means that information/details can be missed which would impact the validity of the findings