Reliability of test results

Attestation of the test procedure is realized with the aim to confirm both the correctness of the choice of method and NDT facilities and fullness of requirements included in the test procedure. Attestation ensures reliability of testing results with required accuracy. 

Quality of analytical equipment specificity, accuracy, precision, and sensitivity of measuring and analyzing equipment determine the reliability of test results. 

Some of the challenges facing the industrial laboratory are limited resources, cost containment, productivity, timeliness of test results, chemical safety, spent chemicals disposal, technician capability, analytical capability, disappearing skills, and reliability of test results. The present R D climate in the chemical industry is one of downsizing at corporate level (lean and mean), erosion of boundaries between basic and applied science, and polymer science and analytical chemistry as Cinderella subjects. Difficult chemical analyses are often run by insufficiently skilled workers (a managerial issue). 

The standard recognizes the factors that determine the correctness and reliability of test results human factors, accommodation and environment, methods, equipment, sampling, and the handling of test items. In this list, measurement traceability is mentioned, but in fact metrological traceability, with measurement uncertainty and method validation, are really subsumed in methods. (subsection 5.4). The effect of each of these factors on measurement uncertainty will differ considerably among kinds of tests. 

Tab. 10.2 Factors influencing the reliability of test results and the detection of SHE frequency...

Various factors (s. tab. 10.2) can influence the reliability of test results. 

If software systems are viewed as a manufacturing facility that produces the desired output products, then statistical sampling procedures and statistical inference can be used to predict the reliability of test results. Instead of paying too much attention to the development of the application, another factor that requires attention is the data (raw material) to be converted into information (product). Information flow is a design technique that may be helpful in achieving this task. 

It is important to recognize that the various standardized methods developed for the analysis of water-based samples are not fail-proof. In this regard, the utility of specific methods and the reliability of test results are dependent upon the use of proper laboratory practices and understanding the limitations of a given method. This section is designed to illustrate some of the important issues in this area. 

The advantage of dry chemistry technology is that it eliminates the need for reagent preparation and many other manual steps common to liquid reagent systems, resulting in greater consistency and reliability of test results. Each test unit contains all the reagents and reactants necessary to perform analyses. 

The purpose of validating an analytical procedure is to d onstrate that it suits the use for which it was conceived. The objective is to dose as exactly and accurately as possible the molecules a laboratory intends to analyze. Validation guarantees the reliability of test results, that is, the measurements carried out with a method are close to true. ... 

No acute-duration oral MRL was derived for endosulfan because no suitable end point was available among the reliable acute-duration studies. The lowest LOAEL, 1.8 mg/kg/day, was for a serious end point, convulsions in pregnant rabbits, appearing 10 days after the start of daily gavage dosing in the EMC (1981) study. Because animals from both the control and the test groups developed ascites, and six rabbits were added without concurrent controls, the reliability of these results is questionable. 

Analytical laboratories need to check their performance with regard to the production of accurate results with satisfactory precision. The most desirable way to ensure the reliability of analytical results is the participation of laboratories into regular interlaboratory tests. An interlaboratory study has to be understood as a study in which several laboratories measure a quantity in one or more identical portions of homogeneous, stable materials under documented conditions, the result of which are compiled into a single document (IUPAC [1994] Prichard et al. [2001]). 

The robustness of an analytical method can be defined as a measure of the capability of the method to remain unaffected by small, but deliberate, variations in method parameters. The parameter therefore provides an indication of the method reliability during normal usage. The ruggedness of a method is the degree of reproducibility of test results obtained by the analysis of the same samples under a variety of conditions, such as different laboratories, different analysts, different instruments, different lot of reagents, different days, etc. 

A critical attitude towards the results obtained in analysis is necessary in order to appreciate their meaning and limitations. Precision is dependent on the practical method and beyond a certain degree cannot be improved. Inevitably there must be a compromise between the reliability of the results obtained and the use of the analyst s time. To reach this compromise requires an assessment of the nature and origins of errors in measurements relevant statistical tests may be applied in the appraisal of the results. With the development of microcomputers and their ready availability, access to complex statistical methods has been provided. These complex methods of data handling and analysis have become known collectively as chemometrics. 

To illustrate the actual importance of dynamic properties for the functioning of metabolic networks, we briefly describe and summarize a recent computational study on a model of human erythrocytes [296]. Erythrocytes play a fundamental role in the oxygen supply of cells and have been subject to extensive experimental and theoretical research for decades. In particular, a variety of explicit mathematical models have been developed since the late 1970s [108, 111, 114, 123, 338 341], allowing us to test the reliability of the results in a straightforward way. 

Reliability is a more customer-friendly term for uncertainty Users of test results, including legislators and competent authorities do not always understand how uncertainty can be used to help them meet their needs. 

If the purpose of the test is to establish whether tlie analyte exceeds or meets some established level, the limit of detection becomes of minor importance, whereas the performance of the test at the level of interest determines actually the reliability of the results. Ideally, screening tests should give no positive results when there are drug residues below the tolerance/MRL level. Equally desired is for the tests to give a positive result 100% of the time when the drug concentration... 

Present-day analytical laboratories are increasingly under pressure to supply objective evidence of their technical competence, of the reliability of their results and performance, and to seek formal certification or accreditation. This pressure may come from the laboratory s customers (e.g., industry and national bodies) but may also be due to scientific considerations. A QM system in place, validation of methods, uncertainty evaluation, the use of primary standards and CRMs, participation in ILCs, and PT, all serve to assure and demonstrate the quality of measurements. Compared to, say, 30 years ago, the stability of the equipment now available is much improved, and a greater range of RMs for method validation and calibration is accessible. Nevertheless, to achieve mutual (international) acceptance of various bodies of evidence for QA activities, a number of protocols have been developed. The most widely recognized protocols used in chemical measurements and testing are the ISO Guide 9000 2000, ISO/IEC 17025 2005, and OECD Guidelines for GLP, as well as its national and sector equivalents. 

There are two categories of common tests for adhesives fundamental property tests and end-use tests. End-use tests, such as peel and shear, are those that try to simulate the type of loading and service conditions to which a joint will be subjected. These tests are relatively straightforward, but experience is required to establish the correct sample type and testing procedures, judge the reliability of the resulting data, and interpret the results and apply them to a practical application. 

Impact Testing (Nonins t rumen ted). Because the Izod impact is a failure test, some scatter of data is expected. Reasons for this scatter include the presence of weak domains, mechanical anisotropy, and any variability in test conditions. Extreme care was taken to maintain constant test conditions. To increase the reliability of the results, 10 test pieces of each sample were tested and the average was calculated. 

To test the reliability of the results obtained, additional computations were performed on the adsorption complexes with extended (HO)3SiOSi(OH)3 and Si(OH)4 + H20 complexes using the extended 3-21G basis set. The results appeared qualitatively quite similar. One could mention only some decrease (to 0.4 kcal/mol) of the energy of (a)-type coordination observed for the extended cluster. This may likely be ascribed to the increased repulsion from the bridged oxygen atom of the extended cluster caused by the... 

The quality and reliability of microarray results largely depend on the quality and consistency of both the substrate and the reagents used to manufacture and process the arrays, but also on the considerable variation in the experimentalist s skills. A number of different substances have been tested as the solid support for nucleic acid immobilization [7,8], but glass slides are generally favored for DNA and oligonucleotide microarrays [9-11]. Optimal... 

Replication involves repeating the experiment under identical conditions. It improves the reliability and validity of test results and is necessary to provide an estimate of experimental error. The number of replications completed is determined by time, cost, and sample constraints. However, the more replications completed, the better the estimate of experimental error and the more reliable the results. 

The theoretical treatment of biomolecular systems is becoming increasingly important in modem science for at least two different reasons. From the one hand, theoretical studies allow to obtain information that cannot be easily accessed by experimental methods and to dissect an overall effect into different contributions simply switching different interactions on and off in a selective way. From the other hand, working hypotheses can be formulated that can stimulate further experimental work and reduce the number of different tests to be performed. Of course, these tasks can be fulfilled only if the accuracy and the reliability of theoretical results match the experimental standards. Whale conventional approaches have reached a remarkable accuracy for small and medium size systems, biologically interesting molecules are invariably large. 

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