Accuracy assessment

Simonson, T. Briinger, A.T., Solvation free energies estimated from macroscopic continuum theory an accuracy assessment, J. Phys. Chem. 1994, 98, 4683-4694... 

Ewing B et al. Base-calling of automated sequencer traces using Phred I Accuracy assessment. Genome Res 1998 8 175-185. 

Ewing, B., Hillier, L., Wendl, M. C., and Green, P. (1998). Base-calling of automated sequencer traces using Phred. I. Accuracy assessment. Genome Res. 8, 175-185. 

Referee Laboratories and Spike Recovery Testing. Outside laboratories, with demonstrated performance records, can be used to evaluate the suitability of a candidate method when none of the other accuracy testing options is feasible. However, This technique provides a very weak form of accuracy assessment. Indeed, it provides a comparability check, not an accuracy measure. Similarly, spike recovery tests provide only weak evidence of method accuracy. Quantitative spike recovery only indicates that the added form of the analyte was recovered. If the added form responds differently toward sample preparation or detection the utility of spike recovery testing remains doubtful. 

So how accurate are DFT calculations It is extremely important to recognize that despite the apparent simplicity of this question, it is not well posed. The notion of accuracy includes multiple ideas that need to be considered separately. In particular, it is useful to distinguish between physical accuracy and numerical accuracy. When discussing physical accuracy, we aim to understand how precise the predictions of a DFT calculation for a specific physical property are relative to the true value of that property as it would be measured in a (often hypothetical) perfect experimental measurement. In contrast, numerical accuracy assesses whether a calculation provides a well-converged numerical solution to the mathematical problem defined by the Kohn-Sham (KS) equations. If you perform DFT calculations, much of your day-to-day... 

Accuracy Assessed using nine Compound % Accuracy... 

The accuracy of an analytical method is the extent to which test results generated by the method and the true value agree. The true value for accuracy assessment can be obtained in several ways. 

One alternative is to compare the results of the method with results from an established reference method. This approach assumes that the uncertainty of the reference method is known. Second, accuracy can be assessed by analyzing a sample with known concentrations (e.g., a certified reference material) and comparing the measured value with the true value as supplied with the material. If such certified reference material is not available, a blank sample matrix of interest can be spiked with a known concentration by weight or volume. After extraction of the analyte from the matrix and injection into the analytical instrument, its recovery can be determined by comparing the response of the extract with the response of the reference material dissolved in a pure solvent. Because this accuracy assessment measures the effectiveness of sample preparation, care should be taken to mimic the actual sample preparation as closely as possible. 

EN17 Daggett, S.G., Greenberg, N. and Peters, C. (1991). Examples of non-physio-logical interferences in external quality control (proficiency test) samples that affect accuracy assessment. Clin. Chem. 37, 959, Abstr. 234. 

Chan, B.K.C. Chan, D.Y.C. Electrical doublelayer interaction between spherical colloidal particles an exact solution. J. Colloid Interface Sci. 1983, 92 (1), 281-283 Palkar, S.A. Lenhoff, A.M. Energetic and entropic contributions to the interaction of unequal spherical double layers. J. Colloid Interface Sci. 1994, 165 (1), 177-194 Qian, Y. Bowen, W.R. Accuracy assessment of numerical solutions of the nonlinear Poisson-Boltzmann equation for charged colloidal particles. J. Colloid Interface Sci. 1998, 201 (1), 7-12 Carnie, S.L. Chan, D.Y.C. Stankovich, J. Computation of forces between spherical colloidal particles Nonlinear Poisson-Boltzmann theory. J. Colloid Interface Sci. 1994, 165 (1), 116-128 Stankovich, J. Carnie, S.L. Electrical double layer interaction between dissimilar spherical colloidal particles and between a sphere and a plate nonlinear Poisson-Boltzmann theory. Langmuir 1996,12 (6), 1453-61. 

The Digital Material is a material description based on measurable quantities that provides the necessary link between simulation and experiment. Critical components of the Digital Material, a feature based material description with a statistical description of attributes, include 1) experimental methods that provide initial data for simulations and simulation methods to evolve the material attributes, 2) simulation tools that can be used to build virtual specimens, characterize them and compute material properties, 3) coordinated experiments to verify simulations and to supplement critical data and 4) accuracy assessment techniques for both simulation and experiment. Development of this program will itself require simulations and experiments of a fundamental nature. The output will be a model that will permit virtual experiments to be conducted on a two-phase material of previously selected and characterized microstructure. 

C.C. Oliveira, R.P. Sartini, E.A.G. Zagatto, J.L.F.C. Lima, Flow analysis with accuracy assessment, Anal. Chim. Acta 350 (1997) 31. 

This expresses the agreement between estimated (or measured) value and the true or reference value [161,162]. Results obtained with flow-based analytical procedure should agree with the certified values (within 95% confidence intervals) associated with standard reference materials, and this is the ideal procedure for accuracy assessment. When certified values are not available, other values, e.g., from intercomparison exercises involving several laboratories are acceptable. If such values are not available, results obtained with official or recommended analytical procedures can be used. If these procedures are not available or if official (or recommended) analytical procedures for the specific analyte do not exist, the results obtained with any properly validated procedure are a minimum requirement. 

Regardless of the protocol for accuracy assessment, several samples covering the entire dynamic range, particularly at the lower end of the range, should always be used [163]. 

Several measurements can be performed on the same sample for e.g., wide-range spectrophotometry, simultaneous determinations, selectivity evaluation, accuracy assessment or compensation of matrix effects by the standard addition method. Each measurement normally relates to a different sample (or standard) volumetric fraction, hence a different degree of dilution. To this end, different approaches involving single or multiple sample (or standard) insertions and/or exploitation of concentration gradients have been used, as emphasised in Chapter 7. 

Li Y, Shen J, Sun X et al (2010) Accuracy assessment of protein-based docking programs against RNA targets. J Chem Inf Model 50 1134-1146... 

Precision and Accuracy Assessment for State and Local Air Monitoring Networks 1988... 

QC accuracy assessments can be challenging when the therapeutic drug shares an endogenous protein. In this case, the endogenous protein concentration can either be added to or subtracted from the final value. Before establishing the calculations, the necessary experiments must be performed, and the consistency of the endogenous value contribution must be documented. 

Estimated From Macroscopic Continuum Theory An Accuracy Assessment. 

K. Kiekens, F. Welkenhuyzen, Y. Tan, P. Bleys, A. Voet, J.P. Kruth, W. Dewulf. A test object with parallel grooves for calibration and accuracy assessment of industrial computed tomography (CT) metrology. Measurement Science and Technology, 22 (2011) 115502. 

Jansen, P.L., Lorenz, R.D., A Physically Insightful Approach to the Design and Accuracy Assessment of Flux Observers for Field Oriented Induction Machine Drives," IEEE Transactions on Industry Apphcations, 1994, 30(1) 101-110. 

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