Reference procedures

What are reference procedures?

In the scientific-technical literature various different definitions of the term "reference procedure" are in use, falling into three main categories as follows:

• Procedure with established high quality of results, which can be used for assessment of other procedures
• Procedure defining a quantity subject to measurement or testing
• Procedure prescribed by legal regulations for specific measurement and testing tasks

Within BAM the term "reference procedure" is used in the sense of the first point with a definition as follows:

Reference procedures are procedures of testing, measurement or analysis, thoroughly characterised and proven to be under control. They are intended for

• quality assessment of other procedures for comparable tasks,
• characterisation of reference materials including reference objects,
• determination of reference values.

The uncertainty of the results of a reference procedure must be adequately estimated and appropriate for the intended use.

The term "reference procedure" applies to testing, measurement and analysis, i.e. all procedures for determining characteristics of materials, products and processes. These characteristics can be of quantitative or qualitative kind, they can be defined independently or by the procedure itself.

Reference procedures are used to validate other procedures, to characterise reference materials or reference objects as well as for determining reference values of materials characteristics. Another application field is testing, measurement or analysis as a basis for important decisions, e.g. for authoritative evidence.

The definition of a "reference procedure" presumes the existence of several procedures for a specified task or of different realisations of the same methodology. Given this, a reference procedure is qualified by the uncertainty of results, proven to be fit for an agreed purpose. Moreover it has to be accepted as such by the relevant target groups.

In the case of quantitative results the uncertainty comprises trueness and precision combined in the sense of measurement uncertainty [1]. In the case of qualitative results the uncertainty is an estimate of the probability of erroneous results. Where possible the assessment of uncertainty includes traceability to the International System of Units (SI) or to other recognised reference systems.

For its various testing activities BAM operates a comprehensive management system complying with the requirements of DIN EN ISO/IEC 17025 ("General requirements for the competence of testing and calibration laboratories"). In many areas this competence is attested and monitored through an accreditation by external bodies.

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