The closeness of agreement between independent measurements obtained under stipulated conditions. Precision quantifies the spread or dispersion of repeated measurement results.
Precision reflects how consistently an instrument produces the same result when measuring the same quantity under the same conditions. High precision means the measurements cluster tightly together, regardless of whether they are close to the true value. Precision is often expressed numerically as standard deviation or variance of a set of repeated measurements.
In metrology, precision encompasses two related but distinct concepts: repeatability and reproducibility. Repeatability refers to precision under identical conditions (same operator, same instrument, same environment, short time frame), while reproducibility refers to precision under changed conditions (different operators, instruments, or locations). Both are important for understanding the overall capability of a measurement system.
For calibration management, precision matters because it determines the minimum uncertainty that can be achieved with a given instrument. Even after an instrument is adjusted for perfect accuracy, its precision places a floor on the quality of measurements it can deliver. When evaluating whether an instrument is suitable for a particular measurement task, both its accuracy and precision must be considered relative to the tolerance requirements of the application.
Precision is the degree to which repeated measurements under unchanged conditions show the same results. It is quantified using statistical measures like standard deviation and indicates the consistency of a measurement system.
Precision is measured by taking multiple readings of the same measurand under controlled conditions, then calculating the standard deviation or range of those readings. Lower spread indicates higher precision.
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