Identify the sampling techniques used to study hidden populations. A. Simple…

Concept

Hidden or hard-to-reach populations often lack a complete sampling frame and may be difficult to contact directly. Researchers therefore use non-probability access methods that work through trusted networks or knowledgeable intermediaries.

Snowball sampling expands the sample through referrals from participants, while key informant sampling selects well-informed people who can provide access to or knowledge about the target population.

Application

Applying this distinction to the four listed techniques:

• Simple random sampling requires an identifiable sampling frame so that every unit can have a known chance of selection.

• Snowball sampling uses participant referrals and is suited to networked, hidden, or hard-to-reach groups.

• Stratified random sampling first divides a known population into strata and then samples probabilistically within them.

• Key informant sampling purposively selects knowledgeable insiders or intermediaries who can describe or help reach the target group.

Contrast

• A and B only mixes one sampling-frame-based probability method with one chain-referral access method.

• A and C only contains two probability methods that depend on an identifiable population structure.

• C and D only mixes a stratified probability method with a purposive informant-based method.

Thus, the techniques intended for studying hidden populations are snowball sampling and key informant sampling; the answer is B and D only.