Research Methods & Study Design

A visual framework organizing outcome domains into three layers: an inner circle of mandatory core domains (recommended 5–9), a middle circle of domains required only in specific circumstances, and an outer circle of candidate domains needing further study. Guides consensus-building and voting in Core Domain Set development.

The process of systematically narrowing down a large list of items or options to focus on the most relevant or important ones — filtering out less suitable elements through a structured review process.