Final answer:
The disadvantage of using case studies for research is the lack of generalizability to a larger population.
Step-by-step explanation:
The disadvantage of using case studies for research is that there is a lack of generalizability. Case studies often focus on specific individuals or groups, which makes it difficult to apply the findings to a larger population. For example, if a case study examines the effects of a certain treatment on one patient, the results may not be applicable to other patients with different characteristics. This limitation hinders the ability to make broad conclusions based on case study findings.