Measurement uncertainty according to ISO/BIPM-GUM

Uncertainty of Thermal Diffusivity Measurements Using the Laser Flash Method

“…The true value associated with the measured property is an idealized notion, which cannot be determined. It is only an approximation or an estimate of the value measured [7][8][9].…”

“…The analyses follow general rules for evaluating and expressing the uncertainty in measurement, established as the ISO GUM method (Guide to the Expression of Uncertainty in Measurement) -the method that has been adopted by various regional metrology and related organizations worldwide [7][8][9]. The GUM approach has been followed in expressing the estimated uncertainty of several thermophysical properties including thermal conductivity using the transient hot-strip technique [10], the guarded hot-plate technique [11], or the transient hot-wire method [12,13].…”

Validation and measurement uncertainty evaluation of the ICP-OES method for the multi-elemental determination of essential and nonessential elements from medicinal plants and their aqueous extracts

“…For consistent interpretation of the measurement results, it is necessary to evaluate the confidence that can be placed in, therefore, the presentation of an analytical result which must be accompanied by indication of the data quality. This information is essential for the interpretation of the analytical result (Kessel 2002;Drolc and Pintar 2011). Method validation is an essential component of the measures that a laboratory should implement in order to produce reliable analytical data (EURACHEM 1998).…”

Use of Pooled Standard Deviation of Paired Samples in Calculating the Measurement Uncertainty by the Monte Carlo Method

“…The GUM lists possible sources of uncertainty in a measurement, including: a) incomplete definition of the measurand; b) imperfect realization of the definition of the measurand; c) nonrepresentative sampling -sample measured may not represent the defined measurand; d) inadequate knowledge of the effects of environmental conditions on the measurement or imperfect measurement of environmental conditions; e) personal bias in reading analogue instruments; f) finite instrument resolution or discrimination threshold; g) inexact values of measurement standards and reference materials; h) inexact values of constants and other parameters obtained from external sources and used in the data-reduction algorithm; i) approximations and assumptions incorporated in the measurement method and procedure; j) variations in repeated observations of the measurand under identical conditions. For Kessel [5] and Silva [6], the evaluation of measurement uncertainties proposed by GUM has been well implemented since 1993 for measuring instruments calibration and measurements in general. According to Martins [7], the application of the GUM is not without difficulties, associated with the need to create a mathematical model that represents the measurement process and to determine the sensitivity coefficients, as well as correlation between input quantities.…”