A particular type of probability sample in which every member of the population has an equal chance of being selected, in any combination.

• A. Simple random sample
• B. Random sampling
• C. Sampling frame
• D. Representative sample

Answer: (A)

This item tests probability sampling where every member has an equal chance of being selected and any combination of individuals of the desired size could appear in the sample. That describes a simple random sample. In an SRS, each member’s chance of inclusion is equal (for a population of size N and sample size n, the inclusion probability is n/N), and all possible samples of size n have the same probability (1 divided by the number of possible samples, which is C(N, n)). This equality across all members and all possible groups eliminates systematic bias in who ends up in the sample and makes subsequent analyses straightforward.

Other terms refer to different ideas. Random sampling is a broad umbrella for randomization methods and doesn’t by itself specify equal probabilities for every individual or every combination. A sampling frame is simply the list from which you draw your sample, not a method of sampling. A representative sample is about the sample reflecting the population’s characteristics, which is an outcome, not the sampling process itself.