Methodology

How the numbers are made.
Openly, and in writing.

Supervisors ask how a figure was produced. So do auditors, validators and your own management body. This is how Halden answers, for data matching, validation, scenario design, model development and governance.

Download the methodology paper (PDF)
01 · Data matching

AI proposes a rule. A person decides whether it becomes one.

Every value in the template comes from a mapping rule: a source range, an optional transform and a target area. You write rules by pointing and clicking, or ask the optional AI assistant to draft them. Either way, a rule is explained, checked and approved before it fills anything.

  1. 01
    Select

    You pick a source range and a template area. Only that evidence is used, and the app shows it before anything is sent.

  2. 02
    Propose

    Rules are written by hand or drafted by the AI assistant against the template's row and column identifiers.

  3. 03
    Explain & check

    Each draft carries its reasoning and passes the same technical checks as a manual rule: target exists, no calculated cells, no overlaps.

  4. 04
    Approve & compile

    A checker approves the rule set; approved rules are deterministic and versioned. AI plays no part in the fill itself.

Draft rule · AI assistantIllustrative
Sourceloans.xlsx · Exposures!C4:C9 TargetCSV_CR_SCEN · rows 0020–0070 · col 0010 Transformvalue / 1,000,000
Reasoning. Source amounts are in euros; the template reports in EUR million. Row labels match the six exposure classes in order.
Target cells exist and are input cellsPassed
No overlap with existing rulesPassed
Template checks on the preview0 blocking
StatusAwaiting checker
02 · Validation

Checks at every step. And all of them again on export.

CheckWhat it catchesWhenStatus
Rule checksTargets outside the template, writes to calculated or formula cells, two rules writing the same cellWhen a rule is savedAvailable
Template data validationsValues outside a cell's dropdown list, with a suggested correctionBefore exportAvailable
Template-aware tab checksSign conventions, percentages entered as whole numbers, zeros where blank selects a different methodology, empty selectorsBefore exportAvailable
Calculated totalsTotals recomputed from the template's own formulas, so you see what the supervisor will seeIn reviewAvailable
Four-eyes approvalA second person approves the exact rule-set version; any change needs new approvalBefore exportAvailable
EBA validation rulesBreaches of the published EBA validation rule setBefore exportPlanned
Plausibility & reconciliationMovements against the prior cycle; differences against FINREP, COREP and the ledgerBefore reviewPlanned
03 · Scenario design

A scenario is a set of paths. Each one with a source, a method and an approver.

StageMethod in Scenario Creator 0.1.0
DataSeries from the ECB Data Portal, Eurostat and CBS StatLine, downloaded from your computer, or your own CSV. Stored with source address, retrieval time and SHA-256. Annual paths; incomplete years are left out.
BaselineAn AR(1) per variable, x(t) = μ + ρ (x(t−1) − μ), estimated by least squares on the history window, with ρ limited to 0–0.95. Alternatives: convergence to the mean, flat, or an entered path.
ShocksDeviations from the baseline that rise to a peak year and then decay by 0.35, 0.7 or 1.0 a year. Templates size them in each series’ historical σ; severities scale them by 0.5, 0.75 or 1.0.
PropagationA VAR(1) on standardised annual data with ridge shrinkage (λ = 0.1 × T). Shocked variables are imposed; the others take their conditional expectation. Linear, and can be switched off per scenario.
ClimateNGFS Phase 5 GDP impacts relative to Current Policies, converted into a growth deviation for the matching country. The carbon price is a fixed path.
ChecksBlocking: missing values, impossible values, sample data at submission. Review: stale data, short history, an adverse path milder than the baseline, GDP down without unemployment rising, no narrative.
ApprovalA content hash covers data, methods, shocks, paths and narratives. With a team server, a checker who is not the maker approves that exact hash.

The checks support a reviewer; they do not certify that a scenario is severe but plausible. The methods are documented approximations and do not replace expert judgement or supervisory guidance. Scenario Creator →

04 · Model development

A lifecycle with gates. Agents can't open them.

In Model Studio, agents carry out the work between gates. Each gate is a decision by a named person, recorded with the evidence it was based on.

  1. Data scan

    Availability, depth and quality

  2. Design

    Gate · methodology approval

  3. Estimation

    Selection, segmentation, calibration

  4. Testing

    Performance, stability, back-tests

  5. Documentation

    Gate · owner sign-off

  6. Validation

    Gate · independent review

  7. Monitoring

    Ongoing performance tracking · Planned

Agent-executed stageHuman approval gate
05 · Governance

Who did what, when, and on which version.

Roles

The EBA Filler and Scenario Creator separate maker and checker. Model Studio adds a model owner and an independent validator, who open its gates. No one approves their own work.

Versioning

Every rule set is versioned and hashed; an approval is bound to that exact version. Re-run any approved version to reproduce its export.

Lineage

From any reported value back to the rule, the approver and the source row.

06 · Model library

Methodology by model type.

PD models

Scorecards and rating models, through-the-cycle and point-in-time.

Model details →

LGD models

Workout and cure-based LGD, including downturn adjustments.

Model details →

EAD & CCF

Credit conversion factors for revolving and off-balance exposures.

Model details →

IFRS 9 ECL

Lifetime PD term structures, staging and macro scenarios.

Model details →

Satellite models

Macro-to-risk links for stress testing and climate scenarios.

Model details →

Behavioural models

Prepayment and non-maturing deposits for IRRBB and NII.

Model details →
Methodology paper

The full methodology, for your validators and supervisors.

How rules are built, checked and approved, what the template checks cover, how lineage and the audit trail work, and what is not yet covered. No form, no gate.

Download PDF · 11 pages All guides & videos →

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