Field,"Conservative u, exact","Conservative u, fuzzy",Basis / assumption
First Name,0.02,0.03,Common-name concentration; deterministic nickname handling first; fuzzy limited to a single minor edit or adjacent transposition and only when the normalized value is at least 5 characters.
Middle Name,0.01,Not used,This field has been dismissed due to observed data quality issues and low selectivity
Last Name,0.005,0.01,Heavy-tailed surname distribution; no phonetics; fuzzy limited to a single minor edit or adjacent transposition and only when the normalized value is at least 5 characters.
Suffix,0.2,Not used,This field has been dismissed due to observed data quality issues and low selectivity
Date of Birth (full),0.0001,Not used,Exact comparison only.
Year of Birth,0.015,Not used,This field has been dismissed due to observed low adoption and low selectivity
ZIP Code (5-digit),0.0003,Not used,Conservative geographic concentration assumption; exact comparison only.
City,0.01,Not used,Exact comparison only.
State,0.06,Not used,Exact comparison only.
Street line,0.00003,0.00006,"Street line and ZIP standardized; ZIP must remain exact. Fuzzy, when allowed, applies only to the street line."
Phone Number,0.000001,Not used,Normalized to E.164
Email Address,0.000001,Not used,Exact comparison only after deterministic normalization.
SSN Last 4 Digits,0.0001,Not used,Exact comparison only.
ITIN Last 4 Digits,0.0001,Not used,Exact comparison only.
Legal ID (full exact value within issuing-authority namespace),0.000001,Not used,Conservative floor for exact DL/passport or equivalent legal identifier; exact comparison only within namespace.
MBI (CMS-issued Medicare Beneficiary Identifier),0.000001,Not used,CMS-issued MBI only; generic insurance identifiers are excluded unless separately validated.
"Namespace bound unique identifiers (e.g. EMPI, FHIR Patient Identifier, CSP UUID, etc.)",≈0,Not used,Exact comparison only; treated as effectively zero collision for under namespace-bound exact matching.
"Insurance Member ID (full individual-level value within payer namespace, i.e., including any dependent suffix)",0.000001,Not used,Conservative floor for exact individual member identifier issued by a single payer; exact comparison only within payer namespace. Family-plan dependent suffixes must be included; a bare subscriber base value without dependent suffix SHALL NOT be treated as a Member ID under this row.
Insurance Subscriber ID (policyholder-level base value within payer namespace),0.0001,Not used,Conservative estimate reflecting documented family-plan sharing: approximately 40% of commercially insured individuals are dependents sharing a base subscriber ID with one or more household members. This degrades the effective per-individual selectivity to roughly the level of SSN last 4 digits. Exact comparison only within payer namespace.
Relationship Linkage — clinical source,0.01,,
Relationship Linkage — self-reported/intake,0.05,,