Fundamentals of Measurement

Accuracy: Closeness with which an instrument reading approaches the true value of the variable being measured.

Precision: A measure of the reproducibility of the measurements or degree to which successive measurements differ from one another.

The following illustration, would give you an idea of accuracy vis-à-vis precision when the bulls eye represents the actual value of the measurand.


Sensitivity: The ratio of output signal or response of the instrument to a change of input or measurand variable.

Resolution: The smallest change in measured value to which the instrument will respond.

Error: Deviation from the true value of the measured value.