On this example, we can notice that the resistor R004 has the lowest standard deviation but the highest mean value. So, if we modify – where it is allowed – the value of the resistor from 1000 by 1040 in the calculation, we can decrease the uncertainty by a factor of 5 (type B) by 0.1% (type A). But this uncertainty would only be valid for the resistor R004.
In our case, it is necessary to apply this determination of uncertainty to determine the uncertainty of the elements of influence which are the reference sensor, the temperature sensor, the acquisition card and various components on the interface card.
If several uncertainties occur for an element, it is necessary to apply Equation 1 (General uncertainty) before applying this equation. It is important to check that all the uncertainties are given in the same confidence interval and that they follow a standard law, otherwise the calculation would be wrong.
Once the uncertainties of the different elements of influence are determined, it is necessary to be able to combine them in order to determine the uncertainty of the pressure sensor under test. To quantify the impact of the influence elements on the sensor, it is necessary to know the best fitted linear equation of the pressure sensor.