S accuracy

There are numerous articles and references on computational research studies. If none exist for the task at hand, the researcher may have to guess which method to use based on its assumptions. It is then prudent to perform a short study to verify the method s accuracy before applying it to an unknown. When an expert predicts an error or best method without the benefit of prior related research, he or she should have a fair amount of knowledge about available options A savvy researcher must know the merits and drawbacks of various methods and software packages in order to make an informed choice. The bibliography at the end of this chapter lists sources for reviewing accuracy data. Appendix A of this book provides short reviews of many software packages. 

The amount of Co in an ore sample is to be determined using a procedure for which Fe is an interferent. To evaluate the procedure s accuracy, a standard sample of ore known to have a Co/Fe ratio of 10.2 1 is analyzed. When pure samples of Co and Fe are taken through the procedure, the following calibration relationships are obtained... 

Caro s acid, H2SO5 is used as a titrant for determining Fe +. Directions are given for exploring the method of end point detection, the titrant s shelf-life, the method s accuracy and precision, and the susceptibility of the method to interference from other species. 

Eortunately, a 3D model does not have to be absolutely perfect to be helpful in biology, as demonstrated by the applications listed above. However, the type of question that can be addressed with a particular model does depend on the model s accuracy. At the low end of the accuracy spectrum, there are models that are based on less than 25% sequence identity and have sometimes less than 50% of their atoms within 3.5 A of their correct positions. However, such models still have the correct fold, and even knowing only the fold of a protein is frequently sufficient to predict its approximate biochemical function. More specifically, only nine out of 80 fold families known in 1994 contained proteins (domains) that were not in the same functional class, although 32% of all protein structures belonged to one of the nine superfolds [229]. Models in this low range of accuracy combined with model evaluation can be used for confirming or rejecting a match between remotely related proteins [9,58]. 

Knowing when the instrument s accuracy was last checked so that you can have confidence in its results - calibration records and labels fulfill this need. 

The measurement uncertainty is transformed into a corresponding uncertainty of the final result due to algebraic distortions and weighting factors, even if the calculator s accuracy is irrelevant. 

Proton NMR Spectra of Zr(benzyl)t (0.06 M) in Styrene and Toluene,Respectively, Obtained with the 220-MHz Spectrometer. 600-Hz Expansion Relative to T.M.S. Accuracy S... 

The broadest class of models, phenomenological models, account explicitly for individual phenomena such as swelling, diffusion, and degradation by incorporation of the requisite transport, continuity, and reaction equations. This class of models is useful only if it can be accurately parameterized. As phenomena are added to the model, the number of parameters increases, hopefully improving the model s accuracy, but also requiring additional experiments to determine the additional parameters. These models are also typically characterized by implicit mean-field approximations in most cases, and model equations are usually formulated such that explicit solutions may be obtained. Examples from the literature are briefly outlined below. 

From the laboratory of K. Y. Kigoshi in Tokyo, we obtained a 2000 year ring sequence of a cedar from the southern tip of Japan, in which Kigoshi had counted and labeled the rings in addition he verified his dates by making 50 radiocarbon measurements in its wood. Although radiocarbon dating s accuracy is only about 40 years, from 50 measurements the verification achieves an accuracy of 40/(50)1/2 or about 6 years. 

This assumption provides a convenient check on the calculation s accuracy, since we already know the fluid s barium content. 

The virial methods differ conceptually from other techniques in that they take little or no explicit account of the distribution of species in solution. In their simplest form, the equations recognize only free ions, as though each salt has fully dissociated in solution. The molality m/ of the Na+ ion, then, is taken to be the analytical concentration of sodium. All of the calcium in solution is represented by Ca++, the chlorine by Cl-, the sulfate by SO4-, and so on. In many chemical systems, however, it is desirable to include some complex species in the virial formulation. Species that protonate and deprotonate with pH, such as those in the series COg -HCOJ-C02(aq) and A1+++-A10H++-A1(0H), typically need to be included, and incorporating strong ion pairs such as CaSO aq) may improve the model s accuracy at high temperatures. Weare (1987, pp. 148-153) discusses the criteria for selecting complex species to include in a virial formulation. 

FDA routinely requires analytical data on tests under review to demonstrate that they measure what they claim to measure. Analytical performance is usually directed at evaluating a test s accuracy or bias compared with a predicate or reference test, precision or repeatability, and analytical specificity and analytical sensitivity. 

Different runs were performed by changing the noise level on the measurements as well as initial value of the parameter. Only a single set of experimental data was considered in our calculations. Table 2 gives a summary of the results, that is, the final value of the parameter obtained from the application of the algorithm, as a function of the initial value and the measurement noise. We can clearly see the effect of the noise level on the parameter estimator s accuracy, as well as its effect on the number of iterations. 

Type of Meter Flowrate (kg/s) Accuracy (per cent FSD over 10 1 range) Type of Material... 

The highest quality reference materials are certified for the concentration values of the constituent(s) of interest, reflecting high confidence in the value s accuracy and the thorough investigation of all known or suspected sources of bias. Used appropriately (e.g., Roper et al., 2001 Zschunke, 2000), these certified values provide an effective means to ensure comparability (both among laboratories and over time). It is not always practical, however, to undertake the work required to produce a certified value in many such cases, a value can be carefully determined, but insufficient information exists to assess the associated uncertainty. This information value is nevertheless of substantial interest to other users of the reference material. It can, for example, allow laboratories to compare results even though full traceability is impractical. 

A student repeatedly measures the iron content in a mineral and finds that the mean of five measurements is 5.62%. The student repeats the measurements again in groups of five and obtains means of 5.61%, 5.62%, and 5.61%. On the basis of this information, what can be said about the student s accuracy (or inaccuracy) ... 

Precision is a measure of the reproducibility of a given result. The role of precision in demonstrating a method s accuracy has not been addressed. However, a clear understanding of the Q.C. method being presented here requires that we briefly examine a few basic features of measurement errors. 

In this chapter the following topics will be reviewed KINPTR s start-of-cycle and deactivation kinetics, the overall program structure of KINPTR, the rationale for the kinetic lumping schemes, the model s accuracy, and examples of KINPTR use within Mobil. As an example, the detailed kinetics for the C6 hydrocarbons are provided. 

The performance verification of Karl Fisher apparatus should include checks for the accuracy and precision of the instrument. The linearity of the instrument should be determined at installation. The first step is to standardize the instrument (see Section 14.3.2) pure water is sufficient for this purpose. Sodium tartrate dihydrate standard (water content 15.66 0.05%) can be used to assess the accuracy, precision, and linearity of the instrument. Typically, one would measure the water content of at least five samples, over the intended instrument user range. For example, the water content of sodium tartrate dihydrate samples that were 65 mg (ca. 10 mg H20), 195 mg (ca. 30 mg H20), 325 mg (ca. 50 mg H20), 455 mg (ca. 70 mg H20), and 650 mg (100 mg H20) could be determined. Calculate the percent water to assess the instrument s accuracy. The results should be within 98 to 102% of 15.66% water. Determine the % RSD of the percent water found to assess the precision of the instrument. The % RSD should be less than or equal to 1%. Finally, plot the expected water content versus the percent water content to assess the linearity of the instrument s response. A correlation coefficient (r) value of 0.999 or greater is acceptable. 

An alternative approach for improving predicted pA(a values has been suggested by Klicic et al. (2002), who developed functional-group-specific linear regression corrections for pA a values computed from a particular DFT SCRF PB formalism. Correction of the raw computed pA(aS increases the model s accuracy to about 0.5 pA" units for those acidic functional groups well represented in their parameterization set. 

In the majority of cases addition of substance A to the reaction zone does not change practically the pressure and, consequently, M — M, and w — w. This is indication that there is no reason for a change in (OH)0 with addition of A, and that the expression (5) is correct. Only in the case of reaction with hydrogen the pressure change amounts to 20-25%, and this is within the method s accuracy. To calculate fcx from eq. (6) it is necessary to know not only lc "oh, but the fcoH constant as well. 

It is crucial to understand that, even assuming a zero peculiar velocity, it is only rarely possible, even in principle, for this process to yield a cosmological redshift to better than 10 km/s accuracy—and, because astronomers have no particular need for highly accurate redshift determinations, the effort to obtain them is rarely made. 

Range of instrument and manufacturer s accuracy Materials of construction, especially of process contact (wetted) parts Process connection details (e.g., chemical seals, capillary lengths, flange rating)... 

The interpretation and implementation of published methods invariably differ at different laboratories due to diversity of utilized instruments, their incidental elements and supplies, and the differences in method interpretation. Each analytical method must be validated at the laboratory before it is used for sample analysis in order to demonstrate the laboratory s ability to consistently produce data of known accuracy and precision. Method validation includes the construction of a calibration curve that meets the acceptance criteria the determination of the method s accuracy and precision and the MDL study. A method SOPs must be prepared and approved for use. Method validation documentation is kept on file and should be always available to the client upon request. 

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