The purpose of ISO 5725 is as follows: a) to outline the general principles to be understood when assessing accuracy (trueness and precision) of measurement methods and results, and in applications, and to establish practical estimations of the various measures by experiment (ISO 5725-1); b) to provide a basic method for estimating the two extreme measures of the precision of measurement methods by experiment (IS0 5725-2); c) to provide a procedure for obtaining intermediate measures of precision, giving the circumstances in which they apply and methods for estimating them (IS0 5725-3); d) to provide basic methods for the determination of the trueness of a measurement method (IS0 5725-4); e) to provide some alternatives to the basic methods, given in IS0 5725-2 and IS0 5725-4, for determining the precision and trueness of measurement methods for use under certain circumstances (IS0 5725-5);
f) to present some practicaI applications of these measures of trueness and precision (IS0 5725-6). 1.2 This part of IS0 5725 is concerned exclusively with measurement methods which yield measurements on a continuous scale and give a single value as the test result, although this single value may be the outcome of a calculation from a set of observations. It defines values which describe, in quantitative terms, the ability of a measurement method to give a correct result (trueness) or to replicate a given result (precision). Thus there is an implication that exactly the same thing is being measured, in exactly the same way, and that the measurement process is under control.
This part of IS0 5725 may be applied to a very wide range of materials, including liquids, powders and solid objects, manufactured or naturally occurring, provided that due consideration is given to any heterogeneity of the material.