What is the purpose of using random samples in research studies?

• A. They always yield exact population parameters.
• B. They require no statistics.
• C. They allow estimation of population properties and to infer about the population.
• D. They are never biased.

Answer: (C)

Random samples are used because they let us learn about a whole population from a smaller group. When everyone has a known chance of being chosen, the sample tends to reflect the population, so we can estimate properties like the average or the proportion and draw inferences about the population as a whole. Exact population parameters aren’t usually obtained from a sample; instead we get estimates with a certain amount of error, and statistics help quantify that uncertainty (confidence intervals, margins of error). So the purpose is to allow estimation of population properties and to infer about the population. While random sampling helps reduce bias, it doesn’t guarantee there will be no bias in practice—issues like nonresponse or a flawed sampling frame can still introduce bias.