Doublechecks

Doublechecks are verification actions performed on a result, document, or process to confirm its correctness by a separate check, typically by someone other than the original performer. The aim is to reduce errors and increase reliability, especially in tasks that affect safety, compliance, or quality.

Common modes include independent re-checks, cross-verification of data, duplicate entry with reconciliation, and applying a second set of eyes before finalizing a decision. In safety-critical contexts, doublechecks often take the form of the four-eyes principle or the two-person rule, requiring two qualified individuals to approve a change or action.

Applications span many domains: in data handling and finance, a second reviewer validates entries or calculations; in medicine and aviation, procedures require multiple confirmations; in software development, code reviews, pair programming, and release approvals serve as doublechecks.

Limitations and considerations include that, while helpful, doublechecks incur time and cost, and can give a false sense of security if both checks share common failings or if independence is compromised. They should be proportionate to risk and designed with clear criteria for success and documented rationale.

Best practices emphasize independence of the checker, the use of documented criteria, logging of results, and periodic review of the process to assess effectiveness. Related concepts include cross-checking, verification and validation, the four-eyes principle, and the two-person rule.