When to deepen sampling of procurement spend
· Maya Ellison
Routine matching catches duplicates and price variances. It does not catch trails that never existed — purchases raised after the fact, approvals skipped under urgency, or category codes that hide off-policy spend.
Widen sampling when three signals appear together: spend growth in a category without a matching headcount or project plan; a cluster of new suppliers paid within sixty days of creation; and exception rates that finance has normalised as 'how we work'.
Deepening a sample does not mean reviewing every invoice. It means selecting transactions where the trail is most likely incomplete — emergency POs, single-source awards, and invoices just under approval thresholds — and reconstructing them end to end.
Write the method before you start. A findings schedule that states population, selection basis, and exceptions is far more useful to an audit committee than a narrative of 'we looked at some invoices'.