Pressure Measurement Glossary-Accuracy and Precision

Does Precision mean the same as Accuracy for Pressure Measurement Devices?

In the context of a pressure measurement device, precision refers to how well it provides repeatable and linear results with increasing or decreasing pressure over many cycles. It is therefore an indication of the quality of measurement technology utilised and is a major factor effecting the cost of an instrument.

Accuracy is very closely connected with precision, but unlike precision it is constrained by a series of fixed reference points or absolute values that all readings are compared with to define the exactness of the instrument. Typically these comparison absolute values are read from a more accurate instrument ideally with a 10 to 1 ratio difference in accuracy to ensure it does not contribute significantly to the overall error calculation.  However in practise it is not always possible to achieve such a high ratio difference in accuracy. When this is the case the overall accuracy should also include the reference instrument uncertainty which better reflects the true accuracy of the device.

A sensors measurement error is normally defined as precision because tight electrical tolerances are difficult to achieve with an analog output signal. Once the zero and full scale points have been ascertained, device scaled via a digital panel meter or other analog to digital converter instrument, the error can then be expressed as accuracy rather than precision. 

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