Target accuracy

To achieve these aims, development of reference methods was required as accuracy targets for lipid and lipoprotein measurements and guidelines were established for analytical performance. 

Reference methods are the gold standards or accuracy targets that have been developed for the more common analytes, such as cholesterol, triglycerides, LDL, and HDL cholesterol. The reference method for cholesterol is fully validated and credentialed through the National Reference System for the Clinical Laboratory. The other methods, although not formally credentialed, have been accepted by consensus. 

The reference method, demonstrated to be readily transferable to other laboratories, has been widely adopted by other reference laboratories and diagnostic manufacturers as the accuracy target and the basis for calibration in cholesterol measurements. 

The Model includes the hypotheses to be tested (vahdation parameters), as well as the general data requirements including the precision and accuracy targets that must be established for each experiment. 

Overall, the accuracy of the capital cost targets is more than good enough for the purposes for which they are used ... 

Table 7.8 contains values of p,/p for the common target elements employed in X-ray work. A more extensive set of mass absorption coefficients for K, L, and M emission lines within the wavelength range from 0.7 to 12 A is contained in Heinrich s paper in T. D. McKinley, K. F. J. Heinrich, and D. B. Wittry (eds.). The Electron Microprobe, Wiley, New York, 1966, pp. 351-377. This article should be consulted to ascertain the probable accuracy of the values and for a compilation of coefficients and exponents employed in the computations. 

The thermographic sensor is used as a remote sensing radiometer when a reference target is imaged. It is usually necessary to correct for emissivity and atmospheric transmission to determine surface temperature with a reasonable degree of accuracy. 

In the use of temperature measurement for control of the separation in a distillation column, repeatability is crucial but accuracy is not. Composition control for the overhead product would be based on a measurement of the temperature on one of the trays in the rectifying section. A target would be provided for this temperature. However, at periodic intervals, a sample of the overhead product is analyzed in the laboratory and the information provided to the process operator. Should this analysis be outside acceptable limits, the operator would adjust the set point for the temperature. This procedure effectively compensates for an inaccurate temperature measurement however, the success of this approach requires good repeatability from the temperature measurement. 

Accuracy of Pyrometers Most of the temperature estimation methods for pyrometers assume that the objec t is either a grey body or has known emissivity values. The emissivity of the nonblack body depends on the internal state or the surface geometry of the objects. Also, the medium through which the therm radiation passes is not always transparent. These inherent uncertainties of the emissivity values make the accurate estimation of the temperature of the target objects difficult. Proper selection of the pyrometer and accurate emissivity values can provide a high level of accuracy. 

Although XRF is generally the X-ray spectrometry method of choice for analysis of major and trace elements in bulk specimens, useful PIXE measurements can be made. A detailed review of the main considerations for thick-target PEXE provides guidance for trace analysis with known and unknown matrices and bulk analysis when the constituents are unknown. Campbell and Cookson also discuss the increased importance of secondary fluorescence and geometrical accuracy for bulk measurements. 

Fig. 3.5. The experimental arrangement used for a typical compressed gas gun is shown. The apparatus is designed to impact a selected impactor upon a target material with precision on the alignment of the impacting surfaces. Velocity at the impact surface can be measured to an accuracy and precision of 0.1%. This loading produces the most precisely known condition of all shock-compression events.

Such models have been developed to achieve a target accuracy of 2 kcal-mol"... 

The predicted atomization energy is 3.6 kcal-mol" higher than the experimental value, resulting in an error about twice as large as the target accuracy. 

Given a certain target accuracy, the enor from each of diese four steps should be reduced below the desired tolerance. The error at a given level may defined as the change which would occur if the calculation were taken to the infinite correlation, infinite basis limit. A typical target accuracy is 1 kcal/mol, so-called chemical accuracy. 

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