Define-Variables Skill

Map each exposure, outcome, covariate, and eligibility variable to a canonical guideline/consensus definition, cross-check it against prior operationalizations in comparable cohorts, then map it to the available DB variables. Call after /design-study (and /search-lit), before /write-protocol.

Inputs

1. Research question (one sentence)
2. Candidate variables — exposure, outcome, key covariates, eligibility filters
3. Data dictionary path (xlsx / csv / markdown) OR explicit list of available DB columns
4. Cohort type (e.g., health-screening, NHANES-like, claims, registry) — informs which prior-art cohort to compare against

Missing inputs → ask once, then proceed.

4-Tier Pipeline (DB codebook + token-efficient literature)

Tier 0 — DB codebook lookup (mandatory for DB-backed observational studies)