9.6.2 Sampling in Qualitative Studies
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Describes Additional Approaches to Sampling in Qualitative Studies: Purposive Convenience and Snowball
Sampling is a crucial aspect of qualitative research. It involves selecting a group of participants that represent the target population in a study. The participants are usually chosen using different methods based on the research question, purpose, and available resources. This teaching piece focuses on additional approaches to sampling in qualitative studies, including purposive, convenience, and snowball sampling.
Purposive Sampling:
Purposive sampling is a non-probability sampling technique used to select participants based on a specific criterion. The criterion may be related to their expertise, experience, or characteristics that align with the research question. For example, if a researcher is interested in exploring the experiences of healthcare professionals in managing patients with chronic conditions, they may purposively sample healthcare professionals with experience in managing such patients. Purposive sampling helps researchers to select participants who are knowledgeable about the research topic, ensuring the validity and credibility of the findings.
Convenience Sampling:
Convenience sampling is a non-probability sampling technique that involves selecting participants who are easily accessible or available. This method is commonly used in exploratory studies or when the researcher has limited time and resources. For example, a researcher may choose to conduct a survey with patients who are waiting in the clinic waiting room. Convenience sampling is not representative of the target population and may introduce bias into the study.
Snowball Sampling:
Snowball sampling is a non-probability sampling technique used to select participants through referrals. The researcher selects a few participants who meet the inclusion criteria and ask them to refer other potential participants. The process continues until the desired sample size is achieved. Snowball sampling is useful when the target population is hard to reach or when the researcher wants to select participants who share similar characteristics or experiences. For example, if a researcher is interested in exploring the experiences of people living with a rare condition, snowball sampling may be an appropriate method to select participants.
| Sampling method | Description | Advantages | Disadvantages |
| Purposive sampling | Participants are selected based on specific criteria that are relevant to the research question | Ensures representation of specific populations or subgroups, allows for in-depth exploration of a phenomenon | Potential for bias if sampling criteria are too narrow or not well-defined |
| Convenience sampling | Participants are selected based on their accessibility and willingness to participate | Easy and cost-effective, useful for pilot studies or when a specific population is difficult to reach | Potential for selection bias and lack of representativeness |
| Snowball sampling | Participants are recruited through referrals from existing participants | Useful for hard-to-reach populations, allows for exploration of hidden populations or sensitive topics | Potential for bias if participants refer others who are similar to them, may not be representative of the broader population |
In conclusion, qualitative research requires a purposive selection of participants who can provide rich data to address the research question. Purposive sampling helps researchers to select participants based on specific criteria related to the research question, while convenience sampling is used in exploratory studies when the researcher has limited time and resources. Snowball sampling is useful when the target population is hard to reach or when the researcher wants to select participants who share similar characteristics or experiences.
References:
- Guest, G., Bunce, A., & Johnson, L. (2006). How Many Interviews Are Enough?: An Experiment with Data Saturation and Variability. Field Methods, 18(1), 59–82. https://doi.org/10.1177/1525822X05279903