{
  "specification_version": "3.4.0",
  "source_document_revision": "AHj4eMT9yK21YUzFwGGh-vnHaxeOM8sbBtiC8OSfCm71Y1VYtWxOuiy2SG3GJI-8WRSfEwjhtEaCMBLoCWf40ZnyE823r9u8RkNjxBh2Qg",
  "table": "Table 4: Sample administrative restrictions on matching combinations",
  "columns": [
    "Candidate combination",
    "P(collision)",
    "Secondary risk category",
    "Why the risk is not fully captured by P(collision)"
  ],
  "rows": [
    {
      "Candidate combination": "Date of Birth + Street Address + ZIP",
      "P(collision)": "3.00E-13",
      "Secondary risk category": "Twin risk; shared living space risk",
      "Why the risk is not fully captured by P(collision)": "Twins, siblings in the same household, and residents in shared or institutional settings may share these fields; address standardization can also collapse distinctions if unit information is missing or inconsistent"
    },
    {
      "Candidate combination": "Email + Date of Birth + City + State",
      "P(collision)": "1.00E-12",
      "Secondary risk category": "Shared contact channel risk",
      "Why the risk is not fully captured by P(collision)": "Email addresses may be shared by spouses, parents, guardians, or caregivers; City and State add limited incremental discrimination"
    },
    {
      "Candidate combination": "First Name + Last Name + Street + Zip",
      "P(collision)": "3.00E-13",
      "Secondary risk category": "Shared contact channel risk; Generational Name risk",
      "Why the risk is not fully captured by P(collision)": "Parent and child generational names in the same household where suffix was either not disclosed or not transmitted"
    },
    {
      "Candidate combination": "Phone + City + State + Zip",
      "P(collision)": "1.8E-13",
      "Secondary risk category": "Reassignment risk; Shared contact risk; Data independence risk",
      "Why the risk is not fully captured by P(collision)": "Though clearly under the threshold, phone numbers are frequently shared or reassigned. City, State, and Zip are not independent."
    },
    {
      "Candidate combination": "First Name + Last Name + DOB + ZIP",
      "P(collision)": "3e-12 (framework)",
      "Secondary risk category": "Above threshold; geographic dependency question",
      "Why the risk is not fully captured by P(collision)": "With Table 3 u-values this combination yields P(collision) = 3e-12, which exceeds the 2e-12 threshold and is ineligible for approval without a formally documented dependency adjustment. The value 3e-13 appears in some prior analyses of this combination, suggesting an implicit discount is being applied to correlated geographic and demographic fields; that discount must be specified and validated before this rule may be reconsidered."
    },
    {
      "Candidate combination": "Last Name + DOB + City + ZIP",
      "P(collision)": "1.5e-12 (framework)",
      "Secondary risk category": "Data independence risk",
      "Why the risk is not fully captured by P(collision)": "City and ZIP are correlated fields — ZIP already encodes city and state. Per §IV.D assumptions, the combination should not receive full independent credit for both. A dependency adjustment reducing the effective contribution of City is warranted before this rule is approved, and the adjusted value should be validated against population data per §IV.F."
    }
  ]
}