Why are random samples used in most research studies?

• A. Because random samples are always cheaper than studying the entire population.
• B. Because sampling is faster but not necessarily representative.
• C. Because random samples allow estimation of population properties with feasible resources.
• D. Because it eliminates any sampling bias entirely.

Answer: (C)

The main idea is that researchers often can’t study every member of a population, so they use samples to learn about the whole group. Random samples are valuable because giving everyone an equal chance to be chosen helps the sample reflect the population’s true characteristics. This makes it possible to estimate population properties—like averages or proportions—with a known level of uncertainty, all while keeping time, money, and effort of the study manageable. It isn’t that random sampling is guaranteed to be perfect, but it provides a practical balance: we can generalize findings to the population and quantify how confident we are in those estimates. The other statements don’t capture this balance as well—cost isn’t guaranteed to be lower, randomness aims to improve representativeness rather than simply being faster, and random sampling doesn’t remove all biases entirely.