The ISO 5725 standard defines accuracy as the combination of trueness and precision. Trueness is the closeness of the mean of a large series of measurements to the accepted reference value, quantifying systematic error or bias. Precision is the closeness of agreement among a set of results, quantifying random error. Thus, accuracy requires both high trueness and high precision.
ISO 5725 Definition of Accuracy
- International Organization for Standardization (ISO)
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).
Type
Disruption
Usage
Precursors
- Earlier statistical work on error analysis by figures like Ronald Fisher
- The need for international harmonization in trade and science
- Development of quality management systems like iso 9000
- Previous national standards on measurement uncertainty
Applications
- laboratory quality assurance (e.g., iso/iec 17025)
- chemical analysis and analytical chemistry
- manufacturing process control
- clinical laboratory testing
- environmental monitoring and compliance
Patents:
Potential Innovations Ideas
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Historical Context
ISO 5725 Definition of Accuracy
(if date is unknown or not relevant, e.g. "fluid mechanics", a rounded estimation of its notable emergence is provided)
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