{
  "tool_id": "art-693-isa530-audit-sampling-mus",
  "kernel_id": "art-693-isa530-audit-sampling-mus",
  "display_name": "ISA 530 Audit Sampling + MUS",
  "tool_version": "1.0.0",
  "mandate_type": "compliance_control",
  "purpose": "Deterministic audit-sampling arithmetic in three caller-declared functions dispatched on method. monetary_unit_sampling sizes a MUS engagement: n = ceil(book_value * confidence_factor / (performance_materiality - expected_misstatement)) and sampling interval = round(book_value / n), failing closed whenever expected_misstatement >= performance_materiality. misstatement_projection applies the tainting method to caller-supplied sampled items (taint = (book - audited) / book, projected misstatement = sum of taint * interval) and adds the basic-precision figure confidence_factor * interval. benford_screen compares the observed first-significant-digit distribution of caller-supplied positive amounts against the Benford expected proportions with a chi-square deviation flag at the 5% level (8 degrees of freedom, critical value 15.507). The method's source standard is ISA 530 (iaasb.org): this node computes the arithmetic of the method and never certifies compliance with any standard, never opines on audit sufficiency, and never selects sample items. No randomness of any kind: the tool performs no selection logic, and any selection start point a caller uses is a caller-declared input, never generated here. Absent, non-numeric, or out-of-domain inputs resolve to INPUT_REJECTED with the field named, never guessed or defaulted.",
  "control_description": "Deterministic audit-sampling arithmetic in three caller-declared functions dispatched on method. monetary_unit_sampling sizes a MUS engagement: n = ceil(book_value * confidence_factor / (performance_materiality - expected_misstatement)) and sampling interval = round(book_value / n), failing closed whenever expected_misstatement >= performance_materiality. misstatement_projection applies the tainting method to caller-supplied sampled items (taint = (book - audited) / book, projected misstatement = sum of taint * interval) and adds the basic-precision figure confidence_factor * interval. benford_screen compares the observed first-significant-digit distribution of caller-supplied positive amounts against the Benford expected proportions with a chi-square deviation flag at the 5% level (8 degrees of freedom, critical value 15.507). The method's source standard is ISA 530 (iaasb.org): this node computes the arithmetic of the method and never certifies compliance with any standard, never opines on audit sufficiency, and never selects sample items. No randomness of any kind: the tool performs no selection logic, and any selection start point a caller uses is a caller-declared input, never generated here. Absent, non-numeric, or out-of-domain inputs resolve to INPUT_REJECTED with the field named, never guessed or defaulted.",
  "declared_inputs": [],
  "declared_outputs": [],
  "kernel_digest": "sha256:e92c7887ebf4004dfc6cc8f68bdea0bc5ae6ac9b7b90356275ea4b1a5ee3cd8c",
  "trust_label": "independently verified: zkVM execution proof (risc0/groth16-bn254)",
  "data_vintage": "2026-09-26",
  "last_validated": "2026-09-26",
  "conformance_fixtures_vendored": true,
  "compute_proof_ready": "ready",
  "wave": 113,
  "source_url": "https://ainumbers.co/chaingraph/art-693-isa530-audit-sampling-mus.html",
  "generated_at": "2026-09-26T18:11:21.795Z"
}