ISO 5725 精确度定义

The International Organization for Standardization (ISO) standard 5725, “Accuracy (trueness and precision) of measurement methods and results,” provides a formal framework to avoid the ambiguity of the common term ‘accuracy’. By decomposing accuracy into two distinct components, it allows for a more rigorous analysis of measurement error. ‘Trueness’ is a qualitative concept that is expressed quantitatively as ‘bias’. It measures how far the mean of a large set of measurements deviates from the true or accepted reference value. A measurement method with high trueness has low systematic error.

‘Precision’ under ISO 5725 is further subdivided into ‘repeatability’ and ‘reproducibility’. Repeatability refers to the variation in measurements taken by a single person or instrument on the same item and under the same conditions (short-term variation). Reproducibility describes the variation arising when using the same measurement process among different instruments, operators, or laboratories (long-term variation). A measurement method is precise if it has small random errors, leading to low variability under both repeatability and reproducibility conditions. Therefore, according to ISO 5725, a measurement is ‘accurate’ only if it is both true (low bias) and precise (low random variation).