Certificates and Measurement Risk Use as-found and as-left calibration results to decide whether earlier measurements need review. This guide focuses on the evidence chain after an instrument is found outside its required condition, rather than treating the certificate as a simple pass/fail document. Direct answer If an as-found calibration result is outside the requirement used by your organization, do not jump directly from "failed calibration" to "all previous measurements are invalid." Preserve the incoming result, identify the affected range or function, determine which products or decisions relied on that range, consider measurement uncertainty and the applicable decision rule, and document the evidence used to decide what needs reinspection or further investigation. Contents Why as-found evidence matters As-found and as-left are different evidence A six-step previous-meas...