Which sampling approach involves selecting participants based on predefined criteria for inclusion, without randomization?

• A. Purposive sampling
• B. Snowball sampling
• C. Convenience sampling
• D. Quota sampling

Answer: (A)

Purposive sampling involves choosing participants who meet predefined inclusion criteria that are directly relevant to the research question, and doing so without randomization. This approach is nonrandom and deliberate: the researcher uses judgment to select individuals who can provide the most pertinent or rich information for studying the topic, such as experts, patients with a specific condition, or users of a particular intervention. Snowball sampling relies on referrals from initial participants, not predefined criteria-driven selection. Convenience sampling picks anyone who is readily available, which may not meet specific inclusion criteria. Quota sampling aims to fill predefined subgroups in fixed numbers, but within each subgroup the selection is typically nonrandom. The defining feature here is meeting explicit inclusion criteria through intentional, nonrandom selection, which is why this approach is the best fit.