Sociology is a science, and therefore sociologists must create scientific studies to prove their theories and demonstrate data.
Some would say that sociology is a "soft science" because sociology does not produce hard and unwavering data like natural sciences or math. However, unlike the "hard sciences," sociology studies humans, which are never one in the same. Therefore, sociological studies must do their research assuming that their studies may not fit into every single person, but that the studies may be overlying to most.