{
      "tool_id": "art-229-compute-disparity-metrics",
      "tool_version": "1.0.0",
      "display_name": "Compute Disparate Impact Metrics",
      "mcp_name": "compute_disparity_metrics",
      "mandate_type": "compliance_mandate",
      "wave": 39,
      "gpu": false,
      "url": "https://ainumbers.co/chaingraph/art-229-compute-disparity-metrics.html",
      "description": "Computes three fair lending disparate impact metrics from aggregate lending counts: 4/5ths (80%) rule (adverse_impact_ratio) per EEOC 29 CFR §1607.4(D), z-statistic for statistical significance of the approval-rate difference, and standardised mean difference (Cohen's d). Inputs are aggregate counts only; no individual applicant records, names, demographic identifiers, or scores. ZERO PII BY CONSTRUCTION. EEOC Uniform Guidelines on Employee Selection Procedures (29 CFR §1607), HMDA/Reg C.",
      "input_schema_ref": "chaingraph/art-229-compute-disparity-metrics.html#manifest",
      "consumes": [
        "art-230-compute-hmda-rate-spread"
      ],
      "feeds": [],
      "status": "live",
      "conformance_fixtures": true,
      "compute_capability": "server",
      "compute_images": [{"system":"sha256-source","image_id":"sha256:1dc8545c4d3f629c66a7ba5ecc65ad105f855135774e745190e7d089b5ad9b27","valid_from":"2026-07-10"},{"system":"risc0","image_id":"sha256:a1a0bc89b5b1febaeda3519f6dbade0fa5ac16beeb143c4e1b01689573567bc6","valid_from":"2026-07-04"}],
      "export_capability": [
        "json"
      ],
      "compute_proof_ready": "ready",
      "compute_proof": {
        "type": "ZkVmReceipt",
        "system": "risc0",
        "receiptFormat": "groth16-bn254",
        "imageId": "sha256:a1a0bc89b5b1febaeda3519f6dbade0fa5ac16beeb143c4e1b01689573567bc6",
        "seal": "BdXJ3wtetYbubXPz3CS5C7kar/WZpvvaLgTwtgAnMGoEkspOwYqmWs9/OpwufQu+VBG8p+A9qd4lTZEIiHYY8xzgzNtUdodd7t9REjqBauFxWEBfhLmDS+pj/inF/N72BknYNn1bKeRqY6z+gUudl4n3vPkgpdjItm2eAw3MLocapJAMzZgWrFYP2bounKY6d04p/s2DEGjx+p0meYnQnRVDKG0E9iWl1sjDPlkT7qOcW1RodfmTtC4y2WSkPOzYH7TVqwf/ly3hr1eEILkfBqvFL5J0sXgZ3w+nGxVNRkYjy3T3YaqVC6x5SC3gkj3k89hz8/n83bTvSsGN0BVg2A==",
        "journal": {
          "chaingraph_version": "0.4.0",
          "kernel_digest": "sha256:1dc8545c4d3f629c66a7ba5ecc65ad105f855135774e745190e7d089b5ad9b27",
          "output": {
            "adverse_impact_ratio": 0.7778,
            "four_fifths_flag": true,
            "four_fifths_result": "ADVERSE_IMPACT_FLAGGED",
            "four_fifths_threshold": 0.8,
            "group_a": {
              "approval_rate": 0.7,
              "approvals": 70,
              "label": "protected_class",
              "total": 100
            },
            "group_b": {
              "approval_rate": 0.9,
              "approvals": 90,
              "label": "control_group",
              "total": 100
            },
            "n_total": 200,
            "odds_ratio": 0.2593,
            "pii_note": "All inputs are aggregate count data only. No individual applicant records are processed. Zero PII by construction.",
            "pooled_proportion": 0.8,
            "regulatory_basis": "29 CFR §1607.4(D) (EEOC UGSP); ECOA 15 USC §1691; 12 CFR Part 1002 (Reg B); HMDA 12 USC §2801; OCC Fair Lending Handbook 2020",
            "standardized_mean_difference": -3.6515,
            "table_source": "29 CFR Part 1607 Uniform Guidelines on Employee Selection Procedures (Federal Register 43 FR 38290 1978-08-25); CFPB HMDA Examination Procedures; OCC Fair Lending Handbook Oct 2020",
            "table_version": "EEOC-UGSP-29CFR1607-2024",
            "two_proportion_z": -3.5355,
            "z_critical_flag_onetail_05": true,
            "z_critical_flag_twotail_05": true,
            "zero_pii_confirmation": "Inputs are aggregate count data only. No individual applicant records processed."
          }
        }
      }
    }