Vitals / Glossary

Glossary

Every term used across the site, one line each.

Architecture

Term	Meaning
Medallion	Three quality tiers — bronze (raw), silver (cleaned/conformed), gold (consumption-ready). A lifecycle, not a schema.
Bronze	Raw ingested data, as-is; schema drift tolerated; PHI present & access-gated.
Silver	De-identified, type-clean, standardized. The PHI boundary — everything downstream reads only from here.
Gold	Consumption-shaped outputs: analytics marts, feature store, vector index.
Delta / Iceberg	Open table formats giving object storage ACID transactions, schema evolution, time travel.
Unity Catalog	Databricks governance layer: catalogs/schemas, table/column access, automatic lineage.
Lineage	The dependency graph from sources → models → outputs (auto-generated from dbt here).

Healthcare data

Term	Meaning
FHIR	HL7's standard for clinical data as JSON Resources (Patient, Encounter, Condition, Observation…). Often exported as NDJSON.
OMOP CDM	OHDSI's Common Data Model — one standard format + vocabulary so disparate sources analyze the same way.
Concept id	OMOP's standard integer code for a clinical concept (e.g. gender 8507 = male); loaded from OHDSI Athena.
ICD-10 / LOINC / SNOMED / RxNorm	Vocabularies for diagnoses / labs & observations / clinical findings / medications.
PHI	Protected Health Information — names, SSN, address, full dates, etc.
Safe Harbor	HIPAA de-identification route: remove 18 specified identifier types.
Date-shift	Shift each patient's dates by a fixed per-patient offset — preserves intervals while de-identifying.
patient_key	Salted-hash surrogate replacing the real patient id.

Standards, organizations & acronyms

Term	Meaning
HL7	Health Level Seven International — publishes FHIR (and older HL7 v2 messaging).
HIPAA	US health-privacy law. Defines PHI and the two de-identification routes.
Expert Determination	HIPAA de-id route #2: a qualified statistician certifies re-identification risk is "very small".
De-identification	Removing PHI so data can be used for analytics/ML. In Vitals: done at the silver boundary.
OHDSI ("Odyssey")	Observational Health Data Sciences and Informatics — the open community maintaining OMOP, its tools, and vocabularies.
Athena	OHDSI's vocabulary repository — where standard OMOP concept_ids are downloaded from.
Interoperability	Different systems exchanging data they can both use — FHIR's purpose.
NDJSON	Newline-delimited JSON — one object per line; the FHIR bulk-export format.
EHR	Electronic Health Record — the clinical source system.
Claims (837 / 835)	Billing data: 837 = claim submitted to the payer; 835 = the payer's remittance/payment.
CPT	Current Procedural Terminology — procedure codes in claims (MRI, physical therapy, injection…).
PRO	Patient-Reported Outcome — a survey the patient fills in (e.g. pain, disability).
ODI	Oswestry Disability Index — the PRO instrument used here (0–100; higher = worse).
Synthea	Open-source synthetic FHIR patient generator — PHI-free data the project can publish.
Value-based care	Paying for outcomes, not volume — the cost mart reflects it.

Transformation & serving

Term	Meaning
dbt	SQL transformation framework: versioned models, tests, docs, lineage. Builds silver→gold here.
Dimensional model	Kimball star schema: dim_ (entities) + fct_ (events/measurements).
Semantic layer / metric	Governed, reusable metric definitions analysts consume (e.g. surgery rate).
Feature store	Serves ML features consistently for training (offline) and scoring (online). Here: Feast.
Vector index	Embeddings of text for similarity search / RAG. Here: pgvector (TF-IDF fallback).
RAG	Retrieval-Augmented Generation: fetch relevant text, feed it to an LLM.
MLflow	Experiment tracking + model registry.

ML & reliability

Term	Meaning
ROC-AUC	Ranking quality of a classifier (0.5 = random, 1.0 = perfect).
Label leakage	A feature that encodes the outcome — inflates offline scores, fails in production. Avoided by using only conservative-care claims.
Feature selection	Using a curated subset of available features in a model (store stays rich, model stays clean).
PSI	Population Stability Index — drift metric per feature: <0.1 stable, 0.1–0.2 moderate, >0.2 significant.
Structured Streaming	Spark's streaming engine; same API as batch. Uses trigger, checkpoint, watermark.
Window function	Per-partition ordered computation (e.g. 7-row rolling mean per patient).

Tooling

Term	Meaning
DuckDB	In-process single-file analytical DB. Runs the MVP with no cloud (Databricks is the deploy target).
mise / uv	Pin tool versions / manage Python deps fast.