Rollup Reconciliation Report¶
Audit report — instantiates Regroupable Aggregation
Reconciles a hierarchy's subtotals against an independent recomputation and its coverage lineage, flagging omissions, double-counts, and drift as an auditable artifact.
A rollup can be arithmetically clean and still be wrong — because a partition was dropped, a unit was counted twice after a reorganization, or a stale branch never refreshed. Rollup Reconciliation Report is the standing artifact that catches this. It reconciles the aggregate two ways: it recomputes the total by an independent path and checks the two agree, and it verifies from coverage lineage that every contributing partition is present exactly once — no omission, no overlap, no double count. Its defining move is proving coverage and agreement, not computing the total; it is an audit over an existing rollup, expressed as a report a human or control can sign off on. It does not define the aggregate's meaning or produce the subtotals — it checks the ones already produced.
Example¶
A hospital network reports its 30-day readmission rate up from wards to hospitals to the whole system, for a regulatory filing. The headline rate looks plausible, but Compliance will not sign it without evidence it is complete and correct. The Rollup Reconciliation Report supplies that. From the coverage lineage it confirms that all 214 wards contributed exactly once — and flags that two wards transferred between hospitals mid-quarter, so their patients appear under both old and new hospital, a double count. It then recomputes the system rate by an independent path — summing raw numerators and denominators directly from the patient-level extract, bypassing the ward and hospital subtotals — and finds the independent figure differs from the rolled-up figure by 0.3 points, exactly the double-counted transfers.
The report renders as a reconciliation statement: total wards expected versus covered, the list of overlapping partitions, the rolled-up rate beside the independently recomputed rate, and the residual difference with its cause. The outcome is not a corrected number but evidence — the rollup is held until the two transfers are de-duplicated, and the signed report becomes the audit trail.
How it works¶
- Prove coverage from lineage. Every partition's identity is checked against the expected set: missing partitions surface as omissions, repeated ones as double counts.
- Recompute independently. A separate, usually simpler path computes the same aggregate without reusing the rollup's intermediate subtotals, so shared bugs cannot hide.
- Difference and attribute. The rolled-up and independent figures are subtracted; any residual beyond the tolerance is traced to specific partitions.
- Render as an artifact. The result is a signed, dated report — coverage, agreement, residuals, causes — not just a boolean.
Tuning parameters¶
- Reconciliation cadence — every close, sampled, or incident-triggered; higher cadence catches drift earlier but costs compute.
- Independence of the reference — how far the recomputation path diverges from the rollup; more independence catches more shared bugs but costs more to maintain.
- Tolerance band — the residual that counts as reconciled; zero for exact ledgers, a decision-linked band for estimated rates.
- Lineage granularity — exact contribution sets versus signed coverage summaries, trading audit precision against storage and privacy.
- Escalation rule — what an unreconciled difference blocks — a warning, a hold, or a hard stop on publication.
When it helps, and when it misleads¶
Its strength is that it turns "the total looks right" into signed evidence of completeness and agreement — the discipline of reconciliation[n1] as a control, catching the omission and double-count failures that pure arithmetic cannot see. It is what lets a rollup be trusted for a regulatory or financial filing.
Its failure mode is a reference that is not truly independent: if the "independent" recomputation quietly reuses the same buggy subtotals or the same flawed lineage, the two agree and certify an error. A tolerance set too loose hides real drift; lineage too coarse cannot localize the cause. The guarding discipline is to derive the reference from a genuinely separate path (raw records, a different system) and to keep lineage fine enough to attribute any residual — treating agreement within tolerance as evidence, not proof, of correctness.
How it implements the components¶
partition_lineage_map— the coverage record that proves every partition contributed exactly once, exposing omission and overlap.reference_computation_path— the independent recomputation the rollup is reconciled against.divergence_monitor— the differencing-and-attribution step that flags residuals beyond tolerance and traces their cause.
It does not define what the total means or produce the subtotals — aggregate_semantics_contract and merge_compatibility_contract belong to Hierarchical Subtotal Rollup, whose output this report audits — and it is not a pre-deployment fuzz harness: the regrouping_test_oracle is Randomized Partition Replay's.
Related¶
- Instantiates: Regroupable Aggregation — it is the archetype's audit mechanism, proving a rollup is complete and correct.
- Consumes: Hierarchical Subtotal Rollup produces the subtotals and total this report reconciles.
- Sibling mechanisms: Hierarchical Subtotal Rollup · Randomized Partition Replay · Versioned Merge Protocol · Mergeable Summary Object · Weighted Moment Accumulator · Tree Reduction · Map–Combine–Reduce Pipeline · Deterministic Pairwise Accumulation · Associativity Property Test
Editorial Notes¶
Form Classification¶
Form family: Assessment, Review & Assurance
Rationale: Rollup Reconciliation Report operates as a bounded evaluation of existing evidence or work that produces a finding or disposition because it reconciles a hierarchy's subtotals against an independent recomputation and its coverage lineage, flagging omissions, double-counts, and drift as an auditable artifact.
Independent corroboration: The frozen evidence defines Rollup Reconciliation Report as 'Reconciles a hierarchy's subtotals against an independent recomputation and its coverage lineage, flagging omissions, double-counts, and drift as an auditable artifact', so its operative form is Assessment, Review & Assurance.
Nearest alternative: Record, Log & Register — Rollup Reconciliation Report includes features of a persistent ledger, log, register, or case record that preserves history and traceability, but its defining operation is a bounded evaluation of existing evidence or work that produces a finding or disposition.
Review outcome: Independent reviewer agreement; medium confidence.
Origin Attribution¶
Primary origin: Accounting & Auditing
Origin pattern: Convergent development
Present-day reach: Multi-domain
Rationale: Reconciling hierarchical totals against independent recomputation is a canonical accounting and audit control.
Related originating lineages:
- Data Science & Analytics — Data-lineage and aggregation validation materially expose omissions and double counts in analytic pipelines.
- Economics & Finance — Economics, finance, and mechanism-design practice supplies a parallel or contributing lineage for the mechanism's defining operation: reconciles a hierarchy's subtotals against an independent recomputation and its coverage lineage, flagging omissions, double-counts, and drift as an auditable artifact.
Review resolution: Both blind reviewers agree that accounting_auditing is the primary historical origin. Explicit reconciliation of alternate origin disagreement, origin mode disagreement, domain reach disagreement, encyclopedia synthesis disagreement starts from reviewer_a’s mechanism-specific evidence: Reconciling hierarchical totals against independent recomputation is a canonical accounting and audit control. Reviewer A proposed alternates=data_science, origin_mode=convergent, domain_reach=multi_domain, and encyclopedia_synthesis=true; reviewer B proposed alternates=economics_finance, origin_mode=single_lineage, domain_reach=specialized, and encyclopedia_synthesis=false. The final record retains every independently supported alternate from either review (data_science, economics_finance) without an arbitrary cap, selects origin_mode=convergent to represent the combined lineage evidence, and keeps domain_reach=multi_domain and encyclopedia_synthesis=true from the more mechanism-specific assessment. Present-day transfer is recorded as reach and is not treated as proof of historical origin.
Encyclopedia synthesis: The exact catalogued form synthesizes established practice rather than reproducing a single standard historical label.
Review outcome: Reconciled after independent review; high confidence.
Notes¶
[n1] Reconciliation is an accounting control that verifies two independently derived figures for the same quantity agree, and investigates any difference; it is the standard mechanism for detecting omission, double counting, and drift in aggregated totals. ↩