Which technique is NOT a validation technique of an audit?

Computer analysis is not traditionally considered a validation technique in the context of auditing, particularly when compared to observation, documentation, and interviews, which are direct methods used to verify the information gathered during an audit.

Observation involves watching processes or activities to ensure they comply with established policies and practices, providing real-time evidence of practices in action. Documentation refers to the review of records, reports, and other written materials that substantiate the compliance and effectiveness of HSE practices. Interviews facilitate discussions with personnel to gain insights, clarify processes, and assess their understanding of health, safety, and environmental procedures.

While computer analysis can be useful in auditing (for example, to analyze large sets of data for trends or anomalies), it typically serves as a supplementary tool rather than a primary validation technique. Validation techniques in auditing focus on obtaining evidence through direct observation and interaction with the audit subject matter, which the other options represent effectively.