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Table 1 Review of four sampling strategies commonly used in community-engaged research

From: Comparing two sampling methods to engage hard-to-reach communities in research priority setting

Sampling method Definition Strengths Limitations Community engagement and rigor
Purposive Sampling [54, 55] Strategy allows for selection of a sampling frame that may be most affected by a specific issue. • Aims to maintain rigor and identify a sampling frame based on specific study driven variables or characteristics. • Requires collaboration from others to identify participants matching characteristics sought.
• Can take time due to specific variables or characteristics sought.
Convenience Sampling [10, 56] Strategy uses existing relationships to identify participants. • Benefits from existing relationships to identify participants.
• Can focus on recruitment from specific locations, settings or activities.
• Efficient and inexpensive.
• May complete quickly.
• May result in homogeneous sampling frame.
• Limited generalizability to broader population.
• Less rigorous if organizations or partners do not follow a process to identify participants.
Snowball Sampling [10, 29, 57] Based on a referral approach where a small number of individuals with specific characteristics recruit others with these characteristics from their networks or community. • Reach to participants with same characteristics.
• Often used in community engagement research studies and mixed methods approaches.
• Based on networks and relationships which may lend credibility to research.
• Referral contact may not be effective in identifying diverse individuals.
• Referral contact may only identify participants meeting specific characteristics.
• Participants may not share information freely for fear of privacy or confidentiality – especially in qualitative study.
Respondent Driven Sampling [30] Used to reach hidden or most-vulnerable populations basing participation and reach on trust of respondent recruiting frame. • Seeds recruit a fixed number of participants.
• Systematic information collected to identify potential biases.
• Requires training and time to capture and identify respondent relationships.
• Reach may not be diverse.
• Bias if great percent of participants share characteristics.