A case study by definition is a triangulation of research methods. A typical case study may employ both qualitative (observations, interviews) and quantitative (surveys) research methods in order to get a holistic picture of the behaviour being studied.

An idiographic approach is a holistic approach to the study of an individual or group with the goal of helping or understanding that individual or group. The goal of most case studies is not to generalize to a larger population.

A case study approach is rich in data. It also is able to determine that the research method itself is not the reason for the results. In a typical case study, I may give an individual a questionnaire, carry out an interview and then put the participant into a situation and observe his/her behaviour. If the findings are all the same, then I know that the conclusions that I am drawing about the participant's behaviour are credible and most likely not due to the choice of research method. In addition, case studies are also usually high in ecological validity. If I carry out a case study on an open office environment in the workplace with the goal of assessing the effect on productivity and worker morale, the study is naturalistic and thus has high ecological validity. A final advantage is that because case studies generate a lot of data and are often of unique or specific cases, new theories may be generated from the research.

The most basic problem of a case study is that it cannot be replicated. Because of the idiographic approach that focuses on the unique nature of individuals and groups, it is also difficult to generalize to other situations. However, qualitative psychologists believe that case study findings can be transferred to similar situations - that is, a study of an international school with roughly 200 students who are all studying IB coursework could be applied to a similar school, but not all schools.

Another disadvantage is that they generate a lot of data that is difficult to analyse. In long-term case studies of groups, attrition of participants can be a problem - that is, people drop out of the study. Another problem with longitudinal case studies is that the researcher may develop a relationship with the participant(s) which jeopardizes the objectivity of the researcher.

The ethical considerations of a case study are the same as for any research in psychology. However, in many cases related to abnormal psychology, there is the issue of informed consent and whether the person being studied understands what it happening. There is also the concern that the desire to study unique events may actually jeopardize the health and/or recovery of individuals. For example, when a case of severe child abuse/deprivation is in the news, there is a desire to study the individual and determine how they cope with their new life. Is this too invasive? What are the costs and benefits to the individual of being studied? To psychology?

In addition, anonymity must be guaranteed and the individual has the right to withdraw from a case study at any time. Finally, the researcher has to keep a "professional relationship" with the participants. In the classic study of Genie, a child who was severely abused by her parents, there was concern that Curtiss was trying to take on the role of parent for Genie and that this relationship was inappropriate and lacking objectivity.

The key to setting up a case study is to, first of all, determine the aim of the case study. Usually, the aim of a case study is quite broad. In the case of HM - it was to study memory and memory loss. In your school, it might be to study stress. Once the aim is determined, then how the case study will be carried out has to be determined. The researchers should consider how the data will be triangulated - that is, what will be the sources of the data? How many members of the school will be chosen to be studied/ How will that be decided? Secondly, how will methods be triangulated? Which methods will be used in order to gather data? Data from all these different research methods and sources will need to be interpreted and conclusions drawn.

Transferability is the term used by qualitative researchers with regard to the generalizability of case studies. The researchers would have to clearly document the characteristics of the school so that readers of the study would be able to determine whether they could potentially draw similar conclusions in their own school. Characteristics which may be important include the size of the school, the level of diversity, is it public or private, is there a rigid admissions procedure, the socio-economic make-up of the student body, the philosophy of the school, the competitiveness of the student body, etc. Since there are so many variables which could affect the nature of this school community, it is very difficult to generalize from a single case study. However, if there are several case studies of similar schools that yield similar results, then these trends will lead researchers to generate hypotheses.