In measurement uncertainty, which elements are typically included in the uncertainty budget?

• A. The final expanded uncertainty value.
• B. Uncertainty sources, their estimates, the combined standard uncertainty, and the coverage factor (k).
• C. Calibration date and instrument serial number.
• D. The measurement unit and its tolerance.

Answer: (B)

In an uncertainty budget, you capture how doubt enters a measurement by listing each uncertainty source, giving its quantitative estimate (usually as a standard uncertainty), and then combining those contributions to form the overall uncertainty. Because the goal is a transparent accounting, you show how each source contributes and how they’re combined, often using root-sum-square for independent effects. To express a stated confidence, you apply a coverage factor to the combined standard uncertainty to obtain the expanded uncertainty, which is what you typically report. The budget itself usually contains the sources, their estimates, the combined standard uncertainty, and the chosen coverage factor. The final expanded uncertainty value is not a separate budget item but the result of multiplying the combined uncertainty by the coverage factor. Metadata like calibration date or instrument serial number, and details like the measurement unit or its tolerance, aren’t part of the uncertainty budget itself.