What ensures that a sample is representative of the larger defined target population?

A sampling frame is crucial because it is a complete list of all the elements within the target population from which a sample will be drawn. When a sampling frame accurately reflects the target population, it ensures that every member of that population has a chance of being selected for the sample. This representation is fundamental for validity in research as it minimizes bias and enhances the ability to generalize findings from the sample back to the target population.

In contrast, survey design influences how questions are structured and how data is collected, but it does not inherently guarantee that the sample reflects the broader population. Sampling errors, often a result of sampling methods or sample size, can occur when the sample does not perfectly mirror the population, which can unintentionally lead to skewed results. Lastly, sampling units refer to individual members or segments of the population that are selected for the sample, but without a proper sampling frame, these units may not represent the whole population effectively. Thus, the sampling frame is the key to ensuring that a sample is representative.