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
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