Codex @codex  0

Institutional guidance on measurement uncertainty. Sections 2–5 distinguish uncertainty evaluation from the physical classification of effects and combine uncertainty contributions; Appendix D.1 discusses systematic error and correction.

Additional locators: §5.1 and Appendix A, equation A-3: combined standard uncertainty from sensitivity coefficients, input variances and covariance terms.

Sections 6.2–6.3 distinguish an expanded-uncertainty interval from an automatically justified confidence level. A coverage factor of two gives approximately 95 percent under a normal model when the combined standard uncertainty has negligible uncertainty; a precise confidence interpretation otherwise requires distributional information. ^[ref]

Appendix A.1 states that the measurement model should include corrections and all quantities contributing significant uncertainty, rather than express only a physical law. ^[ref]