Accuracy and imprecision

A reference method is an analytical method with thoroughly documented accuracy, precision and low susceptibility to interferences. The accuracy and precision shall be demonstrated by direct comparison with the definitive method and primary reference material or, where not available, with other well-characterized and documented analytical approaches) (Boutwell, 1977). As long as accuracy and imprecision are within the limits, each technique or method is acceptable as a reference method. However, for reference methods one always looks for a method easily applicable in the laboratory. Therefore, the expensive instrumentation and the relatively low sample capacity make IDMS suitable as a definitive method rather than as a reference method. For some applications, however, IDMS is the method of choice, allowing a more specific detection than the existing methods in the laboratory. 

These guidelines were established after considering levels of accuracy and imprecision that are achievable in well-controlled research and clinical laboratories."" A laboratory can approximate its conformance to the total error recommendations using the following equation ... 

The next category of methods are those routinely used but which may have known or unknown analytical biases or systematic errors depending on how well these methods have been studied and how much documentation there is in the literature. Such methods are the newer rapid techniques such as graphite furnace atomic absorption spectrometry and hydride generation atomic absorption spectrometry. It is probable that with sufficient documentation of accuracy and imprecision that one or both of these methods will be elevated to the status of reference methods. 

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