Which sampling could be effective when a sampling frame is difficult to identify in research?

RRB Nsg. Superintendent 21 July 2019 (shift 1st)

Nursing Research & Statistics

Medium

Appeared in: RRB Nsg. Superintendent 21 July 2019 (shift 1st)

Explanation

Snowball sampling is specifically designed for situations where a sampling frame is unavailable and the target population is hard to locate.
It operates on a chain-referral basis, where initial participants help recruit subsequent participants from their network.
This method is highly effective for accessing hidden or marginalized populations that are difficult for researchers to find through conventional means.
Examples include studies on commercial sex workers, drug abusers, or individuals with a rare disease, where no official list of the population exists.

Option A: Quota sampling requires the researcher to have prior knowledge of the population's characteristics and their proportions (e.g., 50% male, 50% female). This is not possible if the sampling frame is difficult to identify.
Option B: Convenient sampling involves selecting participants who are most easily accessible. It does not provide a strategy for locating individuals who are hard to find; it simply takes advantage of who is available, leading to high risk of bias.
Option C: Purposive sampling relies on the researcher's judgment to select participants who are considered 'typical' or particularly knowledgeable. This is not feasible if the researcher cannot identify or locate these individuals in the first place.

Visual 1: Flowchart - A diagram illustrating the chain-referral process of snowball sampling, showing how one initial participant leads to the recruitment of several others in successive waves.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Non-probability sampling methods in research as background academic context rather than a clinical decision trigger.
In nursing research, it is often necessary to study vulnerable or hard-to-reach populations to understand health disparities and needs (e.g., homeless individuals, victims of domestic violence, or patients non-adherent to treatment).
Snowball sampling provides a practical method for nurse researchers to access these groups and gather crucial data that would otherwise be unobtainable, leading to better-informed health interventions.
What if? - If the research was on 'nurses' attitudes towards a new hospital policy,' a different method like stratified random sampling (if a list of all nurses is available) or quota sampling would be more appropriate because the sampling frame (list of nurses) is easily identifiable.

How to Approach the Question

First, identify the key challenge presented in the question stem: 'a sampling frame is difficult to identify'. This means you cannot easily create a list of everyone in the population.
Next, review the definitions of each sampling method provided in the options.
Evaluate each option against the challenge. Ask yourself: 'Does this method work if I don't have a list of my population and they are hard to find?'
Quota sampling requires knowing population proportions, so it's out. Convenient sampling just takes who's easy, not who's hidden. Purposive sampling requires you to know who to pick, which you don't.
Recognize that Snowball sampling is the only method that uses referrals to find hidden participants, directly solving the problem in the stem.

Concept Tested & Keywords

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