Which of the following best describes a sample?

• A. A sample is identical to the population.
• B. A sample contains all possible observations.
• C. A sample is a fixed descriptor of the population.
• D. A sample is a subset of observations drawn from the population.

Answer: (D)

A sample represents a subset of observations drawn from a population. It is not identical to the population, nor does it include all possible observations. A sample is not a fixed descriptor of the population—that role belongs to population parameters derived from the entire group or census. The key idea is that a sample is a smaller, drawn portion used to infer characteristics of the whole population, with the understanding that there is sampling error due to not observing every member.