# 22. Calibration – Measurement Uncertainty Setup

2020-11-26

**Measurement Uncertainty Modelling Process Flow**

Before measuring the uncertainty mode, the following things shall be considered

**Measurement Uncertainty Inputs**:- Mean and standard deviations from
**experimental data (type A)**and**expert evaluation (type B)**. - Specification limits from gauge manufacturer
- Certified tolerance for acceptance
- Published datasheet
- Reasonable source for uncertainty.

- Mean and standard deviations from

**Evaluate standard uncertainty from both type A and type B evaluation.**- After completing the listing of uncertainty sources, combine all possible sources with a
**mathematical formula**to express the relation for uncertainty to measurement result. Type A and Type B standard uncertainty shall also be calculated before coming to the next step.

- After completing the listing of uncertainty sources, combine all possible sources with a
**Calculating Sensitive Coefficient**:- When y = f (x1 , x2 , x3)
- Then y’s uncertainty is actually contributed by uncertainties from x1 (u1), x2 (u2) and x3 (u3).

- if x1, x2, x3 is related, then
**u****c****= u****1****+ u****2****+ u****3**

- if x1, x2, x3 is independent completely, then
**u****c²****= u****1²****+ u****2²****+ u****3²**

- When calculating the uncertainty individually, refer to the mathematical and take
**partial derivative**from y to calculate.**u****1****= δy / δx1****u****2****= δy / δx2****u****3****= δy / δx3**

- When y = f (x1 , x2 , x3)

**Calculating Combined Standard Uncertainty and Extended Uncertainty**:

The following process flow are the detailed example of how to setup the measurement uncertainty: