Answer:
The answer is case study.
Explanation:
A case study is a research method that focuses on a single person, group of people or event. These in-depth observations can be generalised to similar cases, which are useful to predict future outcomes.
The greatest advantage of case studies is that they are often inexpensive and highly reliable. For this reason, they are especially convenient for social sciences such as sociology and anthropology, although they are often used in medicine and psychology.