Although random sampling is generally the preferred survey method, few people doing surveys use it because of prohibitive costs; i.e., the method requires numbering each member of the survey population, whereas nonrandom sampling involves taking every nth member. Findings indicate that as long as the attribute being sampled is randomly distributed among the population, the two methods give essentially the same results. If the attribute is not randomly distributed, the two methods give radically different results. In some instances the nonrandom methods yield much better inferences about the population; in other instances, its inferences are much worse. The reasons for this phenomenon are discussed.
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