Documentation

Explanation

Documentation coverage checks whether every required piece of model documentation - purpose, data sources, methodology, assumptions, limitations, validation results, monitoring plans - actually exists and is complete, so that supervisors, auditors, and internal reviewers can understand a model without reverse-engineering it. For regulatory models this is non-negotiable, because incomplete documentation means the bank cannot demonstrate the model is understandable by design. It is measured as Documentation Coverage = Σ(Doc_Component_Weight_i × Completion_Score_i) / Σ(Doc_Component_Weight_i) for regulatory models, a weighted average where each documentation component carries a weight reflecting its importance and a completion score reflecting how fully it is filled in. To implement it, define the mandatory component list and weights, attach a completion score to each (via a structured model-documentation template and a reviewer or automated completeness check), and compute the weighted ratio on every model release and periodic review. Log the per-component scores, the weights used, the reviewer, and the resulting coverage figure as evidence. The threshold is 100% for regulatory models, meaning every weighted component must be complete; any shortfall is a breach that should block the model's approval or continued use and trigger remediation of the missing documentation. Aligns with RBI Understandable by Design, NIST MEASURE 3.1 and 4.1, and ISO Clauses 6.2.2 and 9.1.