⊿ Point. {R} Glossary. ◢ Keyword: N. ◥ University. {q} PhD. {tr} Training. ⚫ UK. ↂ EndNote. ☢️ Convenience. ☢️ NRS. ☢️ Purposive. ☢️ Quota. ☢️ Representative. ☢️ Sample. ☢️ Snowball. ☢️ Volunteer. ☝️ Weerakkody. Sampling: how to select participants in my research study? - PMC.