The research may also continue for an extended period of time, so processes and developments can be studied as they happen.
Amongst the sources of data the psychologist is likely to turn to when carrying out a case study are observations of a person’s daily routine, unstructured interviews with the participant herself (and with people who know her), diaries, personal notes (e.g.
They can help us generate new ideas (that might be tested by other methods).
They are an important way of illustrating theories and can help show how different aspects of a person's life are related to each other.
Case studies allow a researcher to investigate a topic in far more detail than might be possible if they were trying to deal with a large number of research participants (nomothetic approach) with the aim of ‘averaging’.
Because of their in-depth, multi-sided approach case studies often shed light on aspects of human thinking and behavior that would be unethical or impractical to study in other ways.
letters, photographs, notes) or official document (e.g. The case study method often involves simply observing what happens to, or reconstructing ‘the case history’ of a single participant or group of individuals (such as a school class or a specific social group), i.e. The interview is also an extremely effective procedure for obtaining information about an individual, and it may be used to collect comments from the person's friends, parents, employer, workmates and others who have a good knowledge of the person, as well as to obtain facts from the person him or herself.
Most of this information is likely to be qualitative (i.e.
descriptive) data a lot depends on the interpretation the psychologist places on the information she has acquired. In The Pelican Freud Library (1977), Vol 8, Case Histories 1, pages 169-306 Freud, S. Bemerkungen über einen Fall von Zwangsneurose (Der "Rattenmann").
This means that there is a lot of scope for observer bias and it could be that the subjective opinions of the psychologist intrude in the assessment of what the data means.