Case study: Case study is a method of studying phenomena through the analysis of an individual case. The case may be a person, a group, an institution, a classroom, an episode, a process, a society or any other unit of social life. All data relevant to the case are gathered and all available data are organized in terms of the case. The case study method gives a unitary character to the data being studied by inter-relating a variety of facts to a single case. It also provides an opportunity for the intensive analysis of many specific details that are often overlooked with other methods. This approach rests on the assumption that the case being studied is typical of a case of a certain type, so that through intensive analysis generalizations may be made which will be applicable to other cases of the same type.

In brief, case study is a closely-focused analysis of a single unit in which all behaviour is examined using a range of methods. Some measurement is likely to be required (for example, frequency with which males wash-up in a household). The techniques of case study are: observation; interviews; questionnaire; press reports; letters; diaries; participation. 

II. Distinguish between Survey and Case Study:

1. Case Study: A research approach that involves a detailed and thorough analysis of a single case of a unit is called case study.

2. Survey: A survey is a form of planned collection of data for the purpose of description or prediction as to action or analyzing the relationship between certain variables.

3. Surveys are generally conducted on a fairly large scale as contrasted with case studies which tend to be more intensive but on a smaller scale.

4. Case Study is done in terms of limited space and broader time, whereas survey is done in terms of limited time with broader space.