Uncertainty Budget Worksheet

Purpose

The uncertainty budget worksheet for a procedure and range (procedure budget) or for a specific job, following the eight-step method in SOP-16 and UKAS M3003. It records each contribution's source, value, distribution, divisor, sensitivity coefficient, standard uncertainty and degrees of freedom, the combination, the coverage factor and the expanded uncertainty, and the approval and review history.

What it covers

• Contributions
• Combination
• Approval and review history

How to complete it

1. 1.State the measurand and model first. List every contribution from the discipline checklist (SOP-16 section 6.4); do not omit a contribution because it is small - record it and show it is negligible.
2. 2.For Type A: value = standard deviation of the mean, divisor 1, degrees of freedom n - 1. For Type B: value = half-width, divisor per distribution (normal with k: k; rectangular: 1.732; triangular: 2.449; U-shaped: 1.414), degrees of freedom infinite unless the estimate is unreliable.
3. 3.Sensitivity coefficient converts input units to measurand units; record its derivation.
4. 4.Compute u_i = c * value / divisor; u_c = sqrt(sum u_i^2); effective degrees of freedom by Welch-Satterthwaite where any Type A term is significant; k = 2 (or from t-table) and U = k * u_c, rounded up to 2 significant figures.
5. 5.Record approval, review dates and the CMC comparison. The validated ValiTrac Uncertainty Calculator may be used instead of the hand table; attach the printout and record the workbook version.

Before you use it

• Replace every square-bracket token, starting with [LABORATORY NAME], [ADDRESS] and [EFFECTIVE DATE]. The full token list is in GD-01 Read Me First.
• Have the content technically reviewed against how your laboratory actually works, then approved by the responsible manager before it becomes a controlled document.
• Update the Word fields after editing so the table of contents and page numbers are correct: select all, then press F9.
• Record the document in your own document register and set its review date.

Related documents

• QM-01

  Quality Manual

  Top-level description of the management system against every clause of ISO/IEC 17025:2017.

• SOP-16

  Evaluation of Measurement Uncertainty

  GUM-based uncertainty evaluation, budgets, CMC consistency and reporting, aligned with UKAS M3003 principles.

• SOP-21

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• SOP-22

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• SOP-23

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• SOP-24

  Electrical Calibration

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• SOP-25

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• SOP-26

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