A Methodological Framework for Sample Size Determination in Quality Control of Financial Payment Messaging

Within the framework of regulatory compliance and payment systems oversight, financialinstitutions are required to implement rigorous analysis protocols, including ex-post qualitycontrol operations. This paper defines a structured methodological approach for identifyingstatistical samples that are strictly representative of the total population of processedtransactions. The objective is to provide an operational framework that balances applicativesimplicity with statistical rigor, enabling an objective assessment of the statistical error andconfidence levels associated with internal audit processes. Particular attention is devoted tothe specific context of financial sanctions controls, where the statistical unit of interest maydiffer from the monetary unit traditionally employed in financial auditing.