ISO 5725-1:1994 pdf download – Accuracy (trueness and precision) of measurement methods and results
1.1 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 ap- plications, and to establish practical estimations of the various measures by experiment (ISO 5725-I)
b) to provide a basic method for estimating the two extreme measures of the precision of measure- ment methods by experiment (ISO 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 (ISO 5725-3);
d) to provide basic methods for the determination of the trueness of a measurement method (ISO 5725-4);
e) to provide some alternatives to the basic meth- ods, given in ISO 5725-2 and IS0 5725-4, for de- termining the precisior measurement methods fo cumstances (ISO 5725-5); and trueness of * use under certain cir- f) to present some practica I applications of these measures of trueness and precision (ISO5725-6).
1.2 This part of IS0 5725 is concerned exclusively with measurement methods which yield measure- ments 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 observa- tions. 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 un- der 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.
3.2 test result: The value of a characteristic ob- tained by carrying out a specified test method. 3 The measure of trueness is usually expressed in terms of bias. 4 Trueness has been referred to as “accuracy of the mean”. This usage is not recommen ded. NOTE 1 The test method should specify that one or a number of individual observations be made, and their aver- age or another appropriate function (such as the median or the standard deviation) be reported as the test result. It may also require standard corrections to be applied, such as correction of gas volumes to standard temperature and pressure. Thus a test result can be a result calculated from several observed values. In the simple case, the test result is the observed value itself.
4.2.1 The accuracy (trueness and precision) meas- ures should be determined from a series of test re- sults reported by the participating laboratories, organized under a panel of experts established spe- cifically for that purpose. Such an interlaboratory experiment is called an “ac- curacy experiment”. The accuracy experiment may also be called a “precision” or “trueness exper- iment” according to its limited purpose. If the purpose is to determine trueness, then a precision experiment shall either have been completed previously or shall occur simultaneously. The estimates of accuracy derived from such an ex- periment should always be quoted as being valid only for tests carried out according to the standard measurement method.