Identification confidence

Targets for measurement uncertainty describe how accurate and precise the measurements need to be. Targets for identification confidence describe how certain one needs to be that the correct analyte has been identified. 

Establishing method fitness consists of showing that the targets for measurement uncertainty and identification confidence have been met. 

A method s limit is the point where the targets for acceptable measurement uncertainty or identification confidence can no longer be met. Given this definition, the empirical or top-down approach is preferable for describing method limits when... 

Identification criteria are neither absolute nor arbitrary they arise from the level of identification confidence that is considered acceptable for a given application. 

Method limits may be determined according to either qualitative or quantitative considerations the point where identification confidence is unacceptable could be different from the point where precision and accuracy are unacceptable. For qualitative methods, the desired balance between the acceptable rates of false positives and false negatives should be described. 

Show that validation data support claim for diagnostic power of method identification criteria, rates of false outcomes Harmonize with core confirmation criteria Compare diagnostic spectrum with relevant library of spectra Estimate selectivity index of total method Report identification confidence in numeric or prose terms... 

YES/NO outcome based on whether criteria met, identification confidence achieved... 

Because these bottom-up proteomic approaches are conducted in a data-dependent mode, it is foreseeable that other p-lactamases can be identified. In addition, an increase in the detection and identification confidence level is accomplished by the detection of mnlhple pephdes per protein. The discovery of unique pephde bio-... 

Notes Effects of user variability in image cropping and rotation. The identification confidence from the species ANNs is reported before and after recropping and rotation. Off centre was a deliberate attempt to badly crop an image. Numbars greater than 0.5 indicated a correct identification. Numbers less than 0.5 are reported when the system returned no match found, but the first choice was the correct species, nmf refers to situations when there was no positive identification and the first choice was not the correct species. 

Searle, B. C. Turner, M. Identifying peptides the way experts do A scientist-driven scoring system for improving ms/ms peptide identification confidence. Presented at the Association of Biomedical Research Facilities (ABRF) Meeting, Long Beach, CA, 2006. 

Thousands of atoms of 257-104 and 259-104 have ben detected. The Berkeley group believes their identification of 258-104 is correct, but attaches less confidence to this work than to their work on 257-104 and 259-104. 

Analytical investigations may be undertaken to identify the presence of an ABS polymer, characterize the polymer, or identify nonpolymeric ingredients. Fourier transform infrared (ftir) spectroscopy is the method of choice to identify the presence of an ABS polymer and determine the acrylonitrile—butadiene—styrene ratio of the composite polymer (89,90). Confirmation of the presence of mbber domains is achieved by electron microscopy. Comparison with available physical property data serves to increase confidence in the identification or indicate the presence of unexpected stmctural features. Identification of ABS via pyrolysis gas chromatography (91) and dsc ((92) has also been reported. 

Ion exchange (qv see also Chromatography) is an important procedure for the separation and chemical identification of curium and higher elements. This technique is selective and rapid and has been the key to the discovery of the transcurium elements, in that the elution order and approximate peak position for the undiscovered elements were predicted with considerable confidence (9). Thus the first experimental observation of the chemical behavior of a new actinide element has often been its ion-exchange behavior—an observation coincident with its identification. Further exploration of the chemistry of the element often depended on the production of larger amounts by this method. Solvent extraction is another useful method for separating and purifying actinide elements. 

Extended Plant-Performance Triangle The historical representation of plant-performance analysis in Fig. 30-1 misses one of the principal a ects identification. Identification establishes troubleshooting hypotheses and measurements that will support the level of confidence required in the resultant model (i.e., which measurements will be most beneficial). Unfortunately, the relative impact of the measurements on the desired end use of the analysis is frequently overlooked. The most important technical step in the analysis procedures is to identify which measurements should be made. This is one of the roles of the plant-performance engineer. Figure 30-3 includes identification in the plant-performance triangle. 

The cost of performing the hazard identification step depends on the size of the problem and the specific techniques used. Techniques such as brainstorming, what-if analyses, or checklists tend to be less expensive than other more structured methods. Hazard and operability (HAZOP) analyses and failure modes and effects analyses (FMEAs) involve many people and tend to be more expensive. But, you can have greater confidence in the exhaustiveness of HAZOP and FMEA techniques—their rigorous approach helps ensure completeness. However, no technique can guarantee that all hazards or potential accidents have been identified. Figure 8 is an example of the hazards identified in a HAZOP study. Hazard identification can require from 10% to 25% of the total effort in a QRA study. 

The assembly process (Figure 10-1) brings together all of the assessment tasks to provide the risk, its significance, how it was found, its sensitivity to uncertainties, confidence limits, and how it may be reduced by system improvements. Not all PSAs use fault trees and event trees. This is especially true of chemical PSAs that may rely on HAZOP or FMEA/FMECAs. Nevertheless the objectives are the same accident identification, analysis and evaluation. Figure 10-1 assumes fault tree and event tree techniques which should be replaced by the equivalent methods that are used. 

The power of mass spectrometry lies in the fact that the mass spectra of many compounds are sufficiently specific to allow their identification with a high degree of confidence, if not with complete certainty. If the analyte of interest is encountered as part of a mixture, however, the mass spectrum obtained will contain ions from all of the compounds present and, particularly if the analyte of interest is a minor component of that mixture, identification with any degree of certainty is made much more difficult, if not impossible. The combination of the separation capability of chromatography to allow pure compounds to be introduced into the mass spectrometer with the identification capability of the mass spectrometer is clearly therefore advantageous, particularly as many compounds with similar or identical retention characteristics have quite different mass spectra and can therefore be differentiated. This extra specificity allows quantitation to be carried out which, with chromatography alone, would not be possible. 

The degree of confidence in the final estimation of risk depends on variability, uncertainty, and assumptions identified in all previous steps. The nature of the information available for risk characterization and the associated uncertainties can vary widely, and no single approach is suitable for all hazard and exposure scenarios. In cases in which risk characterization is concluded before human exposure occurs, for example, with food additives that require prior approval, both hazard identification and hazard characterization are largely dependent on animal experiments. And exposure is a theoretical estimate based on predicted uses or residue levels. In contrast, in cases of prior human exposure, hazard identification and hazard characterization may be based on studies in humans and exposure assessment can be based on real-life, actual intake measurements. The influence of estimates and assumptions can be evaluated by using sensitivity and uncertainty analyses. - Risk assessment procedures differ in a range of possible options from relatively unso-... 

However, there is a critical lack of information on this system, mainly due to insufficient studies of its spectral signatures, which makes it difficult to insert this molecule with confidence in the astrochemical schemes. During these years, only a few experimental and theoretical studies were performed, aiming to the different spectra useful for interstellar identification and chemistry. Still a lot remains to do. 

The distinction between detection and identification is important, since it may affect the overall response time and options. A detection occurs when a chosen parameter exceeds its threshold value. The detection may be nonspecific—that is, it registers the occurrence of an anomaly but does not necessarily indicate the presence of a particular threat substance. By contrast, identification establishes the identity of the threat substances in a given set. Nonspecific detection systems may have a relatively rapid response time compared with that of specific identification systems, but the former typically provide a lower confidence level that a threat substance is in fact present. In some cases, an alarm from a rapid but nonspecific detection system may be used... 

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