It is one of the qualitative research methods used mostly by the clinical psychologists. It is an in-depth look at the individual in the context of his environment. Sometimes much can be learned from studying just one individual and his unique experiences and behaviors for helping him improve some aspects of his behavior. Even if the focus is on the individual's behavior, yet the case-study method carries implications for understanding human mind and behavior in general.
Usually; case study examines behaviors in the real life context, collecting information about the individual from multiple sources, such as parents, family members, peers, teachers, and other relevant persons in the life of the individual. The background variables that have contributed to the present status of the individual are assessed. His medical, family, and social histories are taken into consideration to understand his unique experiences. The assessment of individual's current level of psychological functioning is done within the context of all the background variables. Such an exercise helps the investigator in understanding the fears, aspirations, and fantasies of the individual, and provides guidelines regarding what can be done to deal with the problems faced by the individual. Usually, case studies have a clinical orientation with a focus on helping the individual for self-improvement. In special cases, case studies of the lives of great persons can be an illuminating experience for those willing to learn from the life experiences of such people.
A researcher while using the case-study method may use psychological tests and questionnaires, and may interview relevant persons to collect information regarding the life experiences of the individual.
The two most important figures in psychology, Sigmund Freud and Jean Piaget, used case-study approach. Freud observed his patients, and his insights led to the development of psychoanalytic school of thought. Jean Piaget observed his children to understand how development takes place, and his insights led to the development of the most powerful theory in developmental psychology. A good deal of insight is required to generalize from the experiences of a single person.
Case studies closely resemble naturalistic observations, as they focus on understanding behaviors in a natural context. But a great deal of caution needs to be exercised when we try to generalize information from case studies. This method has some limitations. First of all, case studies suffer from problems of reliability and validity, because people interviewed may overemphasize certain selected aspects of behavior while ignoring others. The unique experiences that are prone to arouse feelings of shame and guilt may not be easily accessed. It is, therefore, extremely important that researchers use multiple sources of information, objective measurements, and repeated assessments of the relevant variables.