Procurement Anomalies
Benford Second-Digit Test
Applies the Benford second-digit distribution to invoice values for finer anomaly detection.
Why the second-digit Benford test sharpens anomaly detection
Benford's Law predicts the natural frequency of leading digits in genuine financial populations, and material departures point auditors toward fabricated, manipulated or threshold-managed values. The second-digit test refines the first-digit screen, catching subtler distortions such as rounding and bunching that first-digit analysis can miss. AuditPro Core runs the second-digit distribution over invoice values so analytics teams can target sampling at the segments most likely to contain anomalies.
The Numbers
AuditPro Core renders this view from your tenant's live, tamper-evident records. The figures below are illustrative sample data.
Invoices Tested
62,400
Max Deviation
+3.1%
at digit 0
MAD Score
0.018
marginal conformity
Flagged Strata
4
Second-Digit Frequency: Actual vs Expected %
Strata With Greatest Benford Deviation
| Value Band | MAD | Invoices | Verdict |
|---|---|---|---|
| R 9k-10k | 0.031 | 1840 | Non-conform |
| R 19k-20k | 0.026 | 920 | Non-conform |
| R 49k-50k | 0.022 | 610 | Marginal |
| R 99k-100k | 0.019 | 430 | Marginal |
Figures shown are illustrative sample data for demonstration. AuditPro Core renders these views from your own tenant's live, tamper-evident records.
What Benford expects
In many naturally occurring financial datasets, lower digits appear more often than higher ones in a predictable pattern. Significant deviation from that pattern suggests the numbers were not generated naturally.
Why the second digit matters
First-digit tests catch gross distortion; the second-digit distribution is more sensitive to rounding, psychological pricing and amounts engineered just under thresholds. It adds resolution to the screen.
A pointer, not a proof
Benford identifies populations worth examining, not guilty transactions. Conformity does not prove integrity and non-conformity does not prove fraud; both simply direct where to look.
How AuditPro Core Bridges the Gap
- Distribution testing: computes the second-digit frequency over invoice values and compares it to the Benford expectation.
- Deviation scoring: ranks segments by departure from expected frequencies to focus the auditor's sample.
- Drill-through: links anomalous digit bands to the underlying invoices for inspection.
- Continuous monitoring: reruns the test on each data refresh to track emerging distortion.
Key Takeaways
- Second-digit analysis catches rounding and threshold-bunching the first digit misses.
- Benford directs sampling; it does not convict transactions.
- Test reasonably large, homogeneous populations for meaningful results.
- Treat deviation as a starting point for targeted substantive testing.
See This on Your Own Data
AuditPro Core renders this dashboard from your tenant's live, tamper-evident records — every figure traceable to source.