How we sample API trails without drowning in logs

An audit that tries to read every call becomes a delay. An audit that picks only happy-path transfers misses the exceptions regulators care about. Sampling is the craft in between.

Stratify before you randomize

We typically slice by transaction type (credit, debit, reversal), value band, and counterparty class. Random draws happen inside those slices so high-value partner settlements are not drowned by micro top-ups.

Tie every sample to a control claim

If the policy says dual approval above a threshold, the sample must include cases above and below that line. Orphan samples that do not test a claim waste everyone’s time.

Document what you could not see

Missing logs are findings. Saying “insufficient evidence for path X” is more useful than inventing comfort from neighboring paths. Clients who accept that wording early finish remediation sooner.