Text: To others, a random sample is necessary for a case study, case studies are nonnormative research that investigate a situation without prejudice, where we could look at a limited number of cases that would represent the universe overall, and a review of relevant conditions in a specific environment with no attempt to project to a larger universe.
Entailment: Case studies don't necessarily represent overall conditions as a whole.
Contradiction: No one uses case studies for research anymore.