Eligibility criteria are crucial for several reasons:
Ensuring Homogeneity: They help create a uniform group of participants, which minimizes variability and increases the study's internal validity. Improving External Validity: By clearly defining who is eligible, researchers can better generalize their findings to the broader population. Ethical Considerations: Criteria ensure that vulnerable populations are either protected or specifically included if relevant to the study's aims. Resource Optimization: They help focus resources on individuals who are most likely to provide meaningful data.
