Which statement best describes probability sampling?

• A. It guarantees a perfectly representative sample
• B. It ignores sampling frames
• C. It is always easy to implement
• D. It ensures every member has a known, nonzero chance of selection

Answer: (D)

Probability sampling rests on selecting units through random processes so that every member of the population has a known, nonzero chance of being included. That known probability is what allows researchers to quantify sampling error and make inferences to the whole population, even though the sample may not be perfectly representative due to chance and nonresponse. It also depends on a defined sampling frame that identifies who could be selected and assigns those probabilities; ignoring the frame would undermine the method. In practice, probability sampling isn’t always easy to implement because of logistical, cost, or frame quality constraints.