Using sampling concepts, it is found that the correct option is:
(a) Charlie did not use any randomization; he took a convenience sample.
How are samples classified?
- Convenient: Drawn from a conveniently available pool.
- Random: All the options into a hat and drawn some of them.
- Systematic: Every kth element is taken.
- Cluster: Divides population into groups, called clusters, and each element in the cluster is surveyed.
- Stratified: Also divides the population into groups. Then, a equal proportion of each group is surveyed.
In this problem, his classroom is the most convenient sampling method, hence it is a convenient sample, hence option a is correct.
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