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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.