In any device, the difference between the measured value & true value is referred as

Error: The deviation of the measured value from the true value (or) actual value is called error.

Error (E) = Am – At

Am = Measured value

At = True value

This is also called as the Absolute Error.

Important:

Relative Static Error: The ratio of absolute error to the true value is called relative static error.

\(R.S.E = \frac{{\left| {{A_m} - {A_t}} \right|}}{{{A_t}}} \times 100\)

Limiting Error: The maximum allowable error in the measurement is specified in terms of true value, is known as limiting error. It will give a range of errors. It is always with respect to true value, so it is a variable error.

Guaranteed Accuracy Error: The allowable error in measurement is specified in terms of full-scale value is known as a guaranteed accuracy error. It is a variable error seen by the instrument since it is with respect to full-scale value.