Case study, also known as case investigation, is the study of a specific individual, unit, phenomenon or theme. This kind of research collects relevant data extensively, and makes a detailed understanding, arrangement and analysis of the process of the emergence and development of the research object, internal and external factors and their relations, thus forming a thorough and comprehensive understanding and conclusion on related issues.

Extended data

The conditions for applying the case study are:

1, explaining the population with a small sample; After studying a thing, explain the individual with a case;

2. Some things are not universal and representative, but they are worthy of attention, or they can be individual cases;

3. In the application of a certain theory and method, the case is used for feedback, which is verified in practice;

4. It is also the need of accumulating materials, laying the foundation for future case-based research.

In order to select samples with the characteristics and functions that can complete the research task, case studies often adopt purposeful sampling, that is, when we want to know something about selecting samples, we don't need to summarize all similar cases.

Commonly used case sampling can generally include: representative case sampling, key case sampling, extreme case sampling, confirmed and falsified case sampling, comprehensive sampling and so on. No matter what kind of sampling, we should embody the principle of "purpose".