A researcher planning a survey of school principals in a particular state has lists of the school principals employed in each of the 125 school districts. The procedure is to obtain a random sample of principals from each of the districts rather than grouping all the lists together and obtaining a sample from the entire group. Which of the following is a correct conclusion?
(A)This is a simple random sample obtained in an easier and less costly manner than procedures involving sampling from the entire population of principals. (B)This is a cluster sample in which the population was divided into heterogeneous groups called clusters. (C)This is an example of systematic sampling, which gives a reasonable sample as long as the original order of the list is not related to the variables under consideration. (D)This is a stratified sample, which may give comparative information that a simple random sample wouldn't give.
D