Project Details Risks of conformity assessment of a multicomponent material or object in relation to measurement uncertainty of its test results

Project No.:
2016-007-1-500
Start Date:
01 June 2016
End Date:
30 June 2018
Division Name:
Analytical Chemistry Division
Division No.:
500

Objective

To develop an approach for evaluation of the probability of false decisions in conformity assessment of a multicomponent material or object in relation to measurement uncertainty of test (chemical analytical) results of a sample of the material or object. This probability, combining probabilities of false decisions concerning different components of the material or object, will characterize the sample conformity as a whole. The solution to this problem is important for understanding conformity assessment risks in customs control, clinical analysis, pharmaceutical industry, environmental control, and other fields.

Description

The Joint Committee for Guides in Metrology (BIPM and others, including IUPAC) published the document, named “JCGM 106:2012. Evaluation of measurement data – The role of measurement uncertainty in conformity assessment” (link to pdf). This document provides guidance and procedures for assessing the conformity of an item (entity, object or system) with specified requirements. The item might be, for example, a blood sample. These procedures can be applied where the item is distinguished by a single scalar quantity (a measurable property). In other words the conformity assessment is performed separately for every parameter of the item, e.g. one only property of a blood sample from twenty or more properties in a routine blood test report. The same is also in the Eurachem/CITAC Guide 2007 “Use of uncertainty information in compliance assessment, and other known documents”.

When separate conformity assessment for each component of a sample is successful, the total probability of false decisions at the assessment of the sample in whole may still be significant. Such a situation is possible, for example, at customs control of denatured alcohols, where conformity assessment is performed also separately for test results of ethanol and denaturant(s) content. Thus, the problem is that one may “not to see the forest because of the trees”.

Since risk of conformity assessment is probability of false decisions and their severity, evaluation of total probability of false decisions at assessment of a sample of multicomponent material or object (in whole) will be helpful for the risk management.

Progress

December 2016 update – The task group has published a position paper titled “Conformity assessment of multicomponent materials or objects: Risk of false decisions due to measurement uncertainty – a case study of denatured alcohols”, I. Kuselman, F. Pennecchi, R.J.N.B. da Silva, D.B. Hibbert. Talanta 164C (2017):189-195; doi.org/10.1016/j.talanta.2016.11.035

Also relevant to this project is the workshop organized as a satellite event of the Isranalytica Conference and Exhibition, 24-25 Jan 2017, Tel Aviv, Israel.

Related publications:

Kuselman, I. (2017) Validation of test methods, human errors and measurement uncertainty of results. Chemistry International 39/2:40-42 (https://doi.org/10.1515/ci-2017-0231), and Reference Materials 13/1:63-66 (in Russian).

Kuselman, I., Pennecchi, F., da Silva, R.J.N.B., Hibbert, D.B. (2017) Risk of false decision on conformity of a multicomponent material when test results of the components’ content are correlated. Talanta; https://doi.org/10.1016/j.talanta.2017.06.073

Pennecchi, F., Kuselman, I.,  da Silva, R.J.N.B., Hibbert, D.B. (2018)  Risk of a false decision on conformity of an environmental compartment due to measurement uncertainty of concentrations of two or more pollutants. Chemosphere Vol. 202, July 2018, pp. 165-176; https://doi.org/10.1016/j.chemosphere.2018.03.054

See project 2018-004-1-500 for continuation

Page last updated 26 July 2018