Uncertainty Budgets: Check for Double Counting Along the Measurement Chain

Map each contribution to a physical origin

An uncertainty budget documents components and their evaluation. An instrument-level uncertainty statement may already include contributions from its sensing element. Adding the same sensor contribution again as though it were independent can overstate the budget, while omitting uncovered use influences can understate it.

An invented document bundle

Suppose a buyer has a sensor datasheet, an instrument calibration certificate and an installed-system evaluation. Before adding three headline numbers, ask what each statement covers. The system evaluation may already incorporate the instrument calibration information and the sensor’s behavior.

Create a contribution map linking each physical influence to the report that evaluates it. This does not authorize removing a term merely because another number looks similar. Scope, information origin and dependence must be established by the reviewer.

Retain the inclusion decision

For every term, record the source, covered conditions, uncertainty definition, sensitivity and whether it is included elsewhere. Keep excluded terms with a documented reason instead of silently deleting them. Review the resulting budget against the actual measurement model and use conditions.

Primary references: NIST measurement handbook, JCGM international vocabulary.

Measurement review worksheet

This blank worksheet is for your own project. It contains no H M machine trial result.

Customer Questions

Primary References

These references support the technical principles discussed in this guide. The worked examples and review questions are educational.

• NIST measurement handbook
• JCGM international vocabulary