Role Of Measurement Uncertainty Research Articles

Fundamentals in Measurement: The Role of Measurement Uncertainty in Conformity Assessment: Some Examples

Fundamentals in Measurement: The Role of Measurement Uncertainty in Conformity Assessment: Some Examples

The role of measurement uncertainty in the validation of a measurement procedure

The role of measurement uncertainty in the validation of a measurement procedure

Role of measurement uncertainty in the comparison of average areal rainfall methods

The main motivation for this research is the growing awareness of the impact of climate change and the increasing relevance of the United Nations Sustainable Development Goals, aiming to contribute to the measurement of quantities like precipitation and rate of rainfall. This knowledge is widely used in hydrology, climatology and meteorology, providing data and information applied in modelling, pattern definition and recognition, and forecasting. This work is concerned with estimating the average areal rainfall in a stipulated region from rainfall intensity observations made at measurement stations within that region. It focuses on three straightforward estimation approaches: the arithmetic mean method, the Thiessen polygon method and the isohyetal method. The evaluation of the associated measurement uncertainty, for which the law of propagation of uncertainty and a Monte Carlo method as described in guidance documents from the Joint Committee for Guides in Metrology are applied, is the main consideration. The approaches described may be readily applied by practitioners. A comparison of results from applying these methods to a simple example is made. Such results are required for conformity assessment and support in urban management and water resources management worldwide.

Use of the Concept of Measurement Uncertainty in Applied Problems of Metrology

Problems related to the use of the concept of measurement uncertainty in different types of metrological problems, such as calibration, type evaluation, and the verification of measuring instruments are considered. A classification of risks in the assessment of the correspondence of measuring instruments to specific requirements is presented. Examples of conformity decision rules used in verification of measuring instruments are presented and the role of measurement uncertainty in these rules is demonstrated.

The Role of Measurement Uncertainty in Health Technology Assessments (HTAs) of In Vitro Tests.

IntroductionNumerous factors contribute to uncertainty in test measurement procedures, and this uncertainty can have a significant impact on the downstream clinical utility and cost-effectiveness of testing strategies. Currently, however, there is no clear guidance concerning if or how such factors should be considered within Health Technology Assessments (HTAs) of tests.ObjectiveThe aim was to provide an introduction to key concepts in measurement uncertainty for the HTA community and to explore, via systematic review, current methods utilised within HTAs.MethodsHTAs of in vitro tests including a model-based economic evaluation were identified via the Centre for Reviews and Dissemination (CRD) HTA database and key reimbursement authority websites. Data were extracted to explore the specific components of measurement uncertainty assessed and methods utilised. The findings were narratively synthesised.ResultsOf 107 identified HTAs, 20 (19%) attempted to assess components of measurement uncertainty: 15 did so via some form of pre-model assessment (such as a literature review or laboratory survey); four also included components within the economic model; and one considered measurement uncertainty within the model only. One study quantified the impact of measurement uncertainty on cost-effectiveness and found that this parameter significantly changed the results, but did not impact the overall decision uncertainty.ConclusionA minority of HTAs identified from this review used various approaches to assess and/or incorporate the impact of measurement uncertainty, indicating that these assessments are feasible. Uncertainty remains around best practice methodology for conducting such analyses; further research is required to ensure that future HTAs are fit for purpose.Electronic supplementary materialThe online version of this article (10.1007/s40273-018-0638-1) contains supplementary material, which is available to authorized users.

The role of measurement uncertainty in the conformity assessment of the chemical composition of feeds

Official feed inspection has been directly related to the dispersion of the measures achieved by control laboratories, which can be due to several analytical techniques, calculation models and estimation approaches. The present study aims to demonstrate the importance of calculating the measurement uncertainty (MU) in the analysis of the chemical composition of several feedingstuffs, in order to avoid making wrong decisions due to incomplete measures. Samples of feedingstuffs (n=690), collected from 321 establishments, were analyzed. Complete measurements were compared to the labeling information declared by the processor. Animal feeds and mineral mixtures were the most frequent non-compliant samples and, among them, crude protein (n=94), calcium (n=50) and phosphorus (n=40) were the most frequent violations. Method performance was assessed in terms of in-house precision and recovery and by international proficiency testing. MU was calculated by using a bottom-up approach, combined with random effects inherited from the performance evaluation. A top-down approach based on the interlaboratory deviation was also carried out. The MU values calculated by the combined bottom-up approach were mostly lower than those calculated by interlaboratory experimental data. This latter approach overestimated the MU in most results, becoming inadequate. Titrimetric and spectrometric methods presented the higher and the lower MU among all techniques, respectively. A detailed study of the MU plays a key role in the conformity assessment of feedingstuffs, because the use of complete measures avoided 314 wrong decisions taking and prevented the disposal of approximately 1,000,007tons of animal feed.

Drugs WorkBook (DWB): A tool for the analysis of illicit drugs in seized materials

Accurate and reliable analytical measurements are essential when data are to be used to assist the Court in deciding whether or not a drug offence has been committed and therefore about either the innocence or guilt of the accused. The Italian law on drugs demands that compliance with specification limits be assessed on the basis of the actual content of controlled substance contained in seized materials. As a consequence, the role of measurement uncertainty, significant figures and rounding errors becomes critical. In order to assist analysts of forensic toxicology laboratories with illicit drug-related cases, a software tool named Drugs WorkBook (DWB) has been developed. The tool is useful for the quantification of illicit drugs in seized materials along with their measurement uncertainties, the assessment of compliance to specification limits, the printing of comprehensive laboratory reports and the organization of case archives. Other quality control topics, such as control charts, are included. The tool's databases can be edited by the user and maintained up to date. The tool is made freely available to the scientific community.

Evaluation of Measurement Data: The Role of Measurement Uncertainty in Conformity Assessment

Evaluation of Measurement Data: The Role of Measurement Uncertainty in Conformity Assessment

Measurement uncertainty evaluation of automatic Tan Delta and resistivity test set for transformer oil

Quality of transformer oil plays vital role in the performance of transformer in electrical appliances. Measurement uncertainty is a general concept associated with any measurement and can be used in professional decision processes as well as judging attributes in many domains, both theoretical and experimental. As the tolerances applied in industrial production become more demanding, the role of measurement uncertainty becomes more important when assessing conformity to these tolerances. Measurement uncertainty plays a central role in quality assessment and quality standards. In an effort to meet national, international and commercial accreditation requirements, users of transformer oil testing machines must establish adequate methods of determining calibration and test measurement uncertainties. Determining measurement uncertainty for transformer oil testing equipments and test data can be a very complex process. Many factors affect the uncertainty of test data produced by testing machines. In this paper, the concepts associated with the procedure for estimation of uncertainty is discussed and the application of these for the determination of uncertainty in transformer oil testing equipments in government testing labs is illustrated. The objective of this study is to develop a methodology for determining the result of measurement concerning electrical properties of transformer oil and their respective uncertainties.

Role of measurement uncertainties in observed variability in the spectral backscattering ratio: a case study in mineral-rich coastal waters

The particulate backscattering ratio (b(bp)/b(p)) is a useful indicator of the angular scattering characteristics of natural waters. Recent studies have shown evidence both for and against significant spectral variability in b(bp)/b(p) in the visible domain, but most show significant variability in its magnitude. We present results from a case study in which both backscattering and scattering coefficients were measured at nine wavelengths in a region of UK coastal waters where optical scattering is strongly influenced by inorganic particles and where a wide range of turbidities is found in a small geographic area. Using a new approach based on regression analysis of in situ signals, it is shown that, for this study site, most of the apparent variability in the magnitude of the backscattering ratio can be attributed to measurement uncertainties. Regression analysis suggests that b(bp)/b(p) is wavelength dependent for these mineral-rich waters. This conclusion can only be avoided by positing the existence of undocumented, systematic, wavelength-dependent errors in backscattering measurements made by two independently calibrated sensors. These results are important for radiative transfer simulations in mineral-dominated waters where the backscattering ratio has often been assumed to be spectrally flat. Furthermore, spectral dependence also has profound implications for our understanding of the relationship between b(bp)/b(p) and particle size distributions in coastal waters since the commonly assumed power-law distribution is associated with a spectrally flat particulate backscattering ratio for nonabsorbing particles.

The role of measurement uncertainty in doping analysis

The determination of measurement uncertainty is a critical issue in all fields of experimental science; its importance becomes maximal in the specific case of forensic analytical chemistry (including doping analysis), where uncertainty has not only to be calculated with precision, but it also has to be both small and reliable enough to support effective decision making. This contribution gives a general view of the organisation of the activity of the network of the anti-doping laboratories accredited by the World AntiDoping Agency (WADA), focusing in particular on the current situation related to the determination of measurement uncertainty in doping analysis. Representative examples referring to the procedures followed in the case of threshold substances are also presented and discussed.

Role of measurement uncertainty in conformity assessment in legal metrology and trade

Role of measurement uncertainty in conformity assessment in legal metrology and trade

Role of measurement uncertainty in conformity assessment in legal metrology and trade

There is increasing interest in the role of measurement uncertainty in conformity assessment, particularly where measurements are in support of fair trade, health & safety and the environment. A lack of clarity, however, in treating measurement uncertainties and in setting specification limits for compliance may sometimes lead to drastic consequences. Examples concerning conformity assessment, particularly in the measurement of trace quantities (Cd in plastics and antibiotic trace residues in shrimps), are amongst cases identified in the ongoing EU project MetroTrade, which can be significant impediments to international trade. This paper considers the present status of the role of measurement uncertainty in conformity testing, covering both recent work in international standardisation and physical metrology (e.g. OIML recommendations on weighing). One conclusion is that, while much has been achieved, there still exists some work to be done in order to facilitate acceptance of conformity from both customer and supplier and avoid perceived barriers to trade and serious international trade disputes.