Through the scientific method, repeatability and reproducibility fortify accuracy. Unfortunately, differing operators, equipment, calibration, environment, and time introduce variations and potential inaccuracies in measurements. An international standard, ISO 5725-2:2025 helps determine the repeatability and reproducibility of a standard measurement method.
Accuracy, Precision, and Trueness
ISO 5725 uses two terms to describe accuracy: trueness and precision.
Trueness refers to the “closeness of agreement between the arithmetic mean of a large number of
test results and the true or accepted reference value.”
Precision, alternatively, deals with the “closeness of agreement between test results.”
Accuracy, referring to both trueness and precision, is “the closeness of agreement
between a test result and the accepted reference value.”
ISO 5725-2:2025
The ISO 5725 series of standards deal with the accuracy of measurement and results. General considerations are provided in ISO 5725-1:2025 for trueness and precision quantities; therefore, Part One of ISO 5725 is intended to be used in conjunction with ISO 5725-2:2025, as well as any other standard in the series.
ISO 5725-2:2025 covers a basic method for estimating the precision of measurement methods. To meet this purpose, the standard details guidance relevant to all personnel concerned with designing, performing or analyzing the results of the tests for estimating precision.
Changes to ISO 5725-2:2025
In this third edition, ISO 5725-2:2025 revises the 2019 version of the same standard. Through its changes:
- several typos were corrected
- subscripts were made consistent
- references were updated
The previous revision of this standard, ISO 5725-2:2019, saw some notable updates the 1994 edition and incorporated a corrigendum from 2002. It was changed to:
- allow the use of alternative scrutiny and outlier detection tests provided that the performance is similar
- let the user apply modern statistical methods available for calculations of the relevant precision and trueness characteristics
- feature new guidance on the number of laboratories required for a precision study
- include new information on the computation of critical values
ISO 5725-2:2025 – Accuracy (Trueness And Precision) Of Measurement Methods And Results – Part 2: Basic Method For The Determination Of Repeatability And Reproducibility Of A Standard Measurement Method is available on the ANSI Webstore.
Other ISO 5725 Standards
Together, the various ISO 5725 standards outline general principles that need to be understood when assessing the accuracy of measurement methods, along with applications and some specific methods. Other
than Part Two, these standards include:
This standard has a corrigendum: ISO 5725-6/Cor1:2001
All these standards are available together at a discount as the ISO 5725-Accuracy of Measurement Methods and Results Package