Audit Execution and Evidence Gathering
Execution is where the lead auditor controls interview flow, sampling, and evidence quality. Understand the audit trail: criteria → interview/observation → record → conclusion. Evidence types include interviews (testimony), document and record review, and direct observation of activities. Strong evidence is sufficient (enough to conclude), appropriate (relevant to the criterion), and verifiable (another auditor could reach the same conclusion from it).
Concepts to master: sampling (judgmental vs. statistical; sample size and selection rationale), opening and closing meetings, audit trails through processes, tracing a product or record end-to-end, interview technique (open questions first, then probe), and handling resistance or coached answers. The lead auditor manages time, keeps the team on scope, and resolves disagreements within the team before reporting.
Traps: (1) Accepting verbal assurance as sufficient evidence without corroborating records. (2) Sampling only conforming examples (e.g., reviewing only the best-kept batch record). (3) Recording conclusions without the underlying evidence detail. (4) Letting the auditee control the sample. (5) Reporting a systemic conclusion from a single isolated instance, or the reverse-dismissing a systemic pattern as one-off.
Rule of thumb: triangulate. Confirm each significant conclusion with at least two independent evidence sources (e.g., interview plus record plus observation). If sources conflict, expand the sample before concluding.
Worked example: an operator says all inspections are recorded. You verify by selecting a recent lot, observing the inspection, and checking the corresponding record. If the record is missing, the interview claim is contradicted-expand the sample to determine whether it is isolated or systemic.