{
  "specification_version": "3.4.0",
  "source_document_revision": "AHj4eMT9yK21YUzFwGGh-vnHaxeOM8sbBtiC8OSfCm71Y1VYtWxOuiy2SG3GJI-8WRSfEwjhtEaCMBLoCWf40ZnyE823r9u8RkNjxBh2Qg",
  "table": "Table 3: Conservative per-field u-probabilities",
  "columns": [
    "Field",
    "Conservative u, exact",
    "Conservative u, fuzzy",
    "Basis / assumption"
  ],
  "rows": [
    {
      "Field": "First Name",
      "Conservative u, exact": "0.02",
      "Conservative u, fuzzy": "0.03",
      "Basis / assumption": "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."
    },
    {
      "Field": "Middle Name",
      "Conservative u, exact": "0.01",
      "Conservative u, fuzzy": "Not used",
      "Basis / assumption": "This field has been dismissed due to observed data quality issues and low selectivity"
    },
    {
      "Field": "Last Name",
      "Conservative u, exact": "0.005",
      "Conservative u, fuzzy": "0.01",
      "Basis / assumption": "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."
    },
    {
      "Field": "Suffix",
      "Conservative u, exact": "0.2",
      "Conservative u, fuzzy": "Not used",
      "Basis / assumption": "This field has been dismissed due to observed data quality issues and low selectivity"
    },
    {
      "Field": "Date of Birth (full)",
      "Conservative u, exact": "0.0001",
      "Conservative u, fuzzy": "Not used",
      "Basis / assumption": "Exact comparison only."
    },
    {
      "Field": "Year of Birth",
      "Conservative u, exact": "0.015",
      "Conservative u, fuzzy": "Not used",
      "Basis / assumption": "This field has been dismissed due to observed low adoption and low selectivity"
    },
    {
      "Field": "ZIP Code (5-digit)",
      "Conservative u, exact": "0.0003",
      "Conservative u, fuzzy": "Not used",
      "Basis / assumption": "Conservative geographic concentration assumption; exact comparison only."
    },
    {
      "Field": "City",
      "Conservative u, exact": "0.01",
      "Conservative u, fuzzy": "Not used",
      "Basis / assumption": "Exact comparison only."
    },
    {
      "Field": "State",
      "Conservative u, exact": "0.06",
      "Conservative u, fuzzy": "Not used",
      "Basis / assumption": "Exact comparison only."
    },
    {
      "Field": "Street line",
      "Conservative u, exact": "0.00003",
      "Conservative u, fuzzy": "0.00006",
      "Basis / assumption": "Street line and ZIP standardized; ZIP must remain exact. Fuzzy, when allowed, applies only to the street line."
    },
    {
      "Field": "Phone Number",
      "Conservative u, exact": "0.000001",
      "Conservative u, fuzzy": "Not used",
      "Basis / assumption": "Normalized to E.164"
    },
    {
      "Field": "Email Address",
      "Conservative u, exact": "0.000001",
      "Conservative u, fuzzy": "Not used",
      "Basis / assumption": "Exact comparison only after deterministic normalization."
    },
    {
      "Field": "SSN Last 4 Digits",
      "Conservative u, exact": "0.0001",
      "Conservative u, fuzzy": "Not used",
      "Basis / assumption": "Exact comparison only."
    },
    {
      "Field": "ITIN Last 4 Digits",
      "Conservative u, exact": "0.0001",
      "Conservative u, fuzzy": "Not used",
      "Basis / assumption": "Exact comparison only."
    },
    {
      "Field": "Legal ID (full exact value within issuing-authority namespace)",
      "Conservative u, exact": "0.000001",
      "Conservative u, fuzzy": "Not used",
      "Basis / assumption": "Conservative floor for exact DL/passport or equivalent legal identifier; exact comparison only within namespace."
    },
    {
      "Field": "MBI (CMS-issued Medicare Beneficiary Identifier)",
      "Conservative u, exact": "0.000001",
      "Conservative u, fuzzy": "Not used",
      "Basis / assumption": "CMS-issued MBI only; generic insurance identifiers are excluded unless separately validated."
    },
    {
      "Field": "Namespace bound unique identifiers (e.g. EMPI, FHIR Patient Identifier, CSP UUID, etc.)",
      "Conservative u, exact": "≈0",
      "Conservative u, fuzzy": "Not used",
      "Basis / assumption": "Exact comparison only; treated as effectively zero collision for under namespace-bound exact matching."
    },
    {
      "Field": "Insurance Member ID (full individual-level value within payer namespace, i.e., including any dependent suffix)",
      "Conservative u, exact": "0.000001",
      "Conservative u, fuzzy": "Not used",
      "Basis / assumption": "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."
    },
    {
      "Field": "Insurance Subscriber ID (policyholder-level base value within payer namespace)",
      "Conservative u, exact": "0.0001",
      "Conservative u, fuzzy": "Not used",
      "Basis / assumption": "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."
    },
    {
      "Field": "Relationship Linkage — clinical source",
      "Conservative u, exact": "0.01",
      "Conservative u, fuzzy": "",
      "Basis / assumption": ""
    },
    {
      "Field": "Relationship Linkage — self-reported/intake",
      "Conservative u, exact": "0.05",
      "Conservative u, fuzzy": "",
      "Basis / assumption": ""
    }
  ]
}