Zone of uncertainty

The magnitude of the uncertainty associated with a measurement should always be evaluated even if method development is able to generate the best, error-free standard curve possible in order to obtain the best, error-free concentration values for the unknown. Precision and accuracy values define the compromise between the demand for certainty in reported results and the inherent uncertainty in bioanalytical measurement. Precision and Accuracy are the most important parameters used to set the performance standards of bioanalytical methods. They define if the zone of uncertainty connected with the data produced by the method is or is not acceptable for the specific task [13,21]. 

Predicting regulations is not an easy forecast to make, but the zones of uncertainty are decreasing. Some statutory guidance applies. For example, the Delaney Amendment requires a simplistic risk assessment, centering solely on the questions of... 

Figure 9.2 Illustration of differences between the perspectives of the analyst and client with respect to the statistical Zone of Uncertainty for (a) analyses principally directed at qualitative identification and (b) quantitation. Reproduced with permission from material prepared by Dr David N Heller, FDA Center for Veterinary Medicine.

Settlement and Land Use in the Zone of Uncertainty in Upper Mesopotamia. In Rainfall and Agriculture in Northern Mesopotamia (MOS Studies 3) Proceedings of the ThirdMOS Symposium (Leiden 1999), edited by R. M. Jas, 3-35. PIHANS 88. Leiden Nederlands Historisch-Archaeologisch Instituut te Istanbul. 

Once the pure mineral powders characterized, 3 mixtures were manually prepared and named ML1, ML2 and ML3. They contain each of the 8 minerals in different proportions reproducing 3 mine tailings falling in the uncertainty zone of the static test used. The 3 synthetic tailings were characterized with the same techniques as for the pure minerals. Cp and Sp weight fractions were evaluated from their chemical element tracers (respectively Cu and Zn) obtained from ICP-AES analysis. Qz, Dol, and Sid samples are considered pure and their percentages in the mixtures are not corrected. Table 1 presents the fraction of each mineral in the three mixtures before and after correction taking into consideration the contamination of Po sample by pyrite and calcite, as previously determined. The corrected mineral proportions are used for calculation of the static test parameters based on... 

The upper or lower area of the known safe zone which provides a buffer to ensure that no COP value can reach an uncertain or unsafe zone. Buffer zone size is set by technology and manufacturing management based on operating experiences, laboratory studies, theoretical calculations, degree of uncertainty as to process response, reliability of instrumentation including shutdown devices, and probability and consequence of error. The buffer zone is the basis for establishing the N-E-L. No process is intentionally operated in the buffer zone. 

The extent of published observations of the distribution of displacements across fractures comprising a fault damage zone appears to be minimal. Detection of damage zones from seismic data is uncertain at best. Given the availability of software able to represent juxtaposition of beds across a fault zone, this uncertainty can be addressed by assuming various distributions of displacements and testing the sensitivity to these assumptions. This can then indicate the reliance or otherwise which must be placed on the products of deformation in the fault zone for sealing to be predicted. 

Lastly, practically in any kinetic experiment there are some uncertainties in its conditions and results. This concerns such factors as mixing of reactants, regimes of gas flow in different zones of the reaction system, wall effects, axial and radial temperature gradients, spatial distribution of reaction rates, concentrations, pressure, etc. A lot of effort must be applied even to measure the reactant conversion and the main product distributions at the exit of the reactor, needless to say anything about concentrations of active intermediates and concentration distributions inside the reactor. Moreover, up to now there is no clear understanding about which measured parameters are the most informative and should be preferred. 

Tier 2 - Box Model In this tier, the simple box model developed for the BIOSCREEN model (Newell et al., 1996) has been enhanced to include source mass estimation software and other features. The box model estimates source attenuation from a source mass estimate, the mass flux of constituents leaving the source zone, and biodegradation processes in the source zone. The uncertainty in the source lifetime estimate is also provided. 

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