TS ISO 5725-2

TS ISO 5725-2 focuses on how to determine the repeatability and reproducibility of a standard measurement method when assessing the accuracy of measurement methods and results. It provides a basic, practical approach for estimating precision through collaborative interlaboratory experiments, helping users understand how consistently the same method performs across laboratories.

What repeatability and reproducibility mean

In general technical usage, repeatability describes how close successive measurements are under the same laboratory conditions, while reproducibility describes how closely results agree between different laboratories. That distinction matters because a method can perform well in one setting yet vary when used by different analysts, instruments, or facilities. Within the ISO 5725 framework, these concepts are part of the precision profile of a measurement method and are closely linked to standard deviation estimates used to express measurement variability.

The application context covered by this part

• It applies only to measurement methods that produce results on a continuous scale and yield a single test result, even when that result is calculated from several observations.
• It assumes a balanced, uniform-level experiment in which each laboratory provides the same number of results and analyses the same levels of test sample.
• It describes the basic method for procedures that have been standardized and are in routine use in multiple laboratories.
• It is suitable when the test materials are homogeneous, or when any heterogeneity can be incorporated into the precision values.
• It uses the statistical model from ISO 5725-1 for interpreting results that are approximately normally distributed.
• The same approach can also be used to obtain a preliminary estimate of precision for methods that are not yet standardized or not yet in routine use.

The document also guides personnel involved in designing, conducting, or analysing precision tests. In practice, that makes it both a methodological reference and a framework for organising interlaboratory studies so that precision can be expressed in a comparable way across users and laboratories.

The basic method is only one part of the wider ISO 5725 series. Other parts address modifications for particular purposes, so this part should be understood as the core reference approach rather than a catch-all procedure for every measurement scenario.