Validation and Measurement Uncertainty

Method validation allows the characterization and assessment of a method’s performance. While for qualitative methods, this is done in terms of sensitivity, specificity and more advanced performance characteristics such as LOD, for quantitative methods, the aim is to obtain estimates of the method’s bias and precision. Precision estimates can then be used to support an estimate of measurement uncertainty following the top-down approach.

Fields of application in which we have been particularly involved in recent years involve food microbiology, residues in products of animal origin, test-kits, digital PCR, multi-methods and the coupling of machine learning algorithms and MS in connection with food origin / species identification. 

Verification, In-house validation

QuoData can help you conduct a verification or in-house validation study in accordance with the requirements of ISO/IEC 17025:2017. For a verification study, the aim is to show that your laboratory is competent to use a method which has already been validated. For an in-house validation study, the aim is to show that your method meets relevant performance criteria. Due to our considerable experience and our role in international standardization, QuoData can offer valuable guidance regarding experimental design, the statistical model for the estimation of performance characteristics, and the application of assessment criteria. In particular, the use of highly efficient designs can considerably reduce the workload. While we have been applying these standards for 20 years, they have only recently been taken up in international standards (e.g. ISO 16140 and the revision of ISO 5725). Do not hesitate to get in touch with us in order to benefit from our unique expertise.

Interlaboratory validation

As far as the standardization and validation of methods intended to be used in different laboratories is concerned, QuoData provides comprehensive services, including planning, experimental design, setting up an online platform for communication with participants and data submission, checks on data integrity and plausibility, data evaluation, and reporting/publishing results.

The following papers provide a cross-section of our activities and expertise in method validation:

• Uhlig, S. et al. (2015): Validation of qualitative PCR methods on the basis of mathematical-statistical modelling of the probability of detection. Accreditation and Quality Assurance 20.2. 75-83.

• Uhlig, S.; Gowik, P. (2018): Efficient estimation of the limit of detection and the relative limit of detection along with their reproducibility in the validation of qualitative microbiological methods by means of generalized linear mixed models. Journal of Consumer Protection and Food Safety 13.1. 79-87.

• Hettwer et al. (2018): Validation of Arxula Yeast Estrogen Screen assay for detection of estrogenic activity in water samples: Results of an international interlaboratory study. Science of the Total Environment 621:612-625.

• Uhlig, S.; Niewöhner, L.; Gowik, P. (2011): Can the usual validation standard series for quantitative methods, ISO 5725, be also applied for qualitative methods? Accreditation and quality as-surance 16.11: 533.

• Uhlig, S.; Gowik, P. (2009): Factorial interlaboratory tests for microbiological measurement methods. J Verbrauch Lebensm, 5(1):35–46.

Measurement uncertainty

Since the new revision of ISO/IEC 17025, there is a new emphasis on achieving a correct evaluation of measurement uncertainty. QuoData plays a central role in providing conceptual clarification and practical guidance. Not only have we developed a highly use-friendly software implementation of the GUM approach, but we have also developed a web-tool for the evaluation of measurement uncertainty in the field of soil analysis. Do not hesitate to get in touch with us if you need theoretical or practical guidance.

The following examples provide an insight in our activities and expertise in the evaluation of measurement uncertainty

• Webtool for taking measurement uncertainty into account in the implementation of the Federal Soil Protection and Contaminated Sites Ordinance and underlying concept. 

• “Measurement uncertainty in the case of large and heterogeneous variances: A new method for the calculation of asymmetric uncertainty intervals”. Presented at “Eurachem Workshop Uncertainty from sampling and analysis for accredited laboratories”. Berlin 2019.

• “How to address matrix mismatch bias in the uncertainty budget”. Presented at “Eurachem Workshop Uncertainty from sampling and analysis for accredited laboratories”. Berlin 2019.