In most disciplines, studies are required to prove a hypothesis. These studies are usually very large in nature, with the goal of proving a hypothesis. With a case study, a narrow topic is chosen that can prove (or disprove) an idea, question or hypothesis. Often, case studies are used alongside a larger formal study, or are used on their own.

Case studies are used in most disciplines that use or require statistical or informational data. For example, a well-known case study in the field of psychology is the case of "Genie", a feral child.

Obviously, researchers cannot lock up a child for a decade, and do research on the results. So, when a child was discovered locked up for 13 years, it was a perfect opportunity to do research and try to discover what the effects were of a child being isolated their entire life.