What it means
PCI evidence sampling selects representative systems, locations, users, events, configurations, and time periods so an assessor can form a defensible conclusion about control operation.
Why it matters
Convenience samples can hide variation, exceptions, or locations where the control is weakest, while samples that are too small or unexplained undermine confidence in the conclusion.
Practical focus
- Define the population and select samples across technologies, locations, roles, risk, time periods, and control implementations.
- Explain why the sample is representative and expand it when evidence is inconsistent or exceptions appear.
- Preserve population data, selection rationale, tested items, results, deviations, and follow-up.
- Preserve this evidence: Retain approved definitions, decisions, operating records, exceptions, test results, and change history that show how PCI Evidence Sampling works over time.
- Exercise this failure scenario: Only the best-documented location is sampled even though other sites use different technology and operating procedures.
Common mistakes
- Using PCI Evidence Sampling as a label without defining its scope, owner, decision criteria, and expected evidence.
- Treating a diagram, policy, tool screen, or meeting as proof that PCI Evidence Sampling operates consistently in real work.
- Optimizing for a one-time review while leaving normal operating decisions, exceptions, and handoffs uncontrolled.
- Testing only the expected path and never rehearsing this failure condition: Only the best-documented location is sampled even though other sites use different technology and operating procedures.
Certification relevance
This subject appears in or supports the following certification bodies of knowledge: