A university has 4,000 freshmen, 3,500 sophomores, 3,000 juniors, and 2,500 seniors. To study study-abroad interest, an administrator separates students by class level and then randomly selects 40 freshmen, 35 sophomores, 30 juniors, and 25 seniors to interview.
Which sampling method is being used?
- A
Cluster sample
- B
Convenience sample
- Ccheck_circle
Stratified random sample
- D
Simple random sample
Explanation
Students are partitioned into homogeneous groups (strata) by class level and an SRS is drawn from each stratum. This is the defining structure of a stratified random sample.