Activities

The use of uncertainty

02/02/2022
Uncertainty calculation in chemical analysis
- Why is measurement uncertainty is important?
- Why do we need to know how to estimate measurement uncertainty?

• It is required by ISO 17025 – Accreditation.
• Establishing traceability for the measurements.
• It improves the knowledge about the measurement procedure.
• To allow comparison of results.
• Your best defense in discussions!

Type A and Type B uncertainty

02/02/2022
Uncertainty calculation in chemical analysis
Type A evaluation
Evaluation of a component of measurement uncertainty by a statistical analysis of measured quantity values obtained under defined measurement conditions.
* type A uncertainty is based on the experimental results and is quantified in terms of the standard deviation of the repeated measurements.
02/02/2022
Uncertainty calculation in chemical analysis
Type B evaluation
Evaluation of a component of measurement uncertainty determined by means other than a Type A evaluation of measurement uncertainty.
Evaluation based on information,
- associated with authoritative published quantity values.
- associated with the quantity value of a certified reference material.
- obtained from a calibration certificate.
- about drift.
- obtained from the accuracy class of a verified measuring instrument.
- obtained from limits deduced through personal experience.