In short: Calibration compares an instrument with a reference standard, while measurement uncertainty quantifies the doubt around any measurement result. Both are needed to make reliable decisions about product conformity.
What is calibration?
A comparison of an instrument’s readings with a traceable reference, documenting any deviation and, if needed, adjusting the instrument.
What is measurement uncertainty?
A parameter describing the range within which the true value is expected to lie, combining effects such as the instrument, operator, method and environment.
Why does it matter for conformity?
When a result is close to a specification limit, uncertainty can determine whether you can confidently claim a pass or fail.
Key takeaways
- Use calibrated, traceable instruments.
- Estimate uncertainty for critical measurements.
- Consider uncertainty near specification limits.
Frequently asked questions
What is traceability?
An unbroken chain of calibrations linking a measurement to national or international standards.
How often should instruments be calibrated?
Based on usage, stability, risk and manufacturer guidance.
Is uncertainty the same as error?
No. Error is the difference from the true value; uncertainty describes the doubt about the result.