INDEX statistical evaluation

Based on previous recommendations [31], a combination of graphical techniques and error index statistics was used for evaluating the goodness-of-fit between the simulated and observed streamflow values, both during the calibration and validation period. The used statistics were the mean error (ME), the percent bias (PBIAS, [32]) and the Nash-Sutcliffe efficiency (NSeff, [33]) ... 

An index of aromatic character based upon statistical evaluation of the deviations in peripheral bond orders has been devised and applied to five-membered ring heterocycles and their mesoionic derivatives including 1,2,3,4-thiatriazole <85TI409> and 5-phenyl-l,2,3,4-thiatriazol-3-oxide <93T8441>. See also <93QSAR146>. 

A new index of aromaticity has been proposed and applied to neutral and mesoionic five-membered heterocycles. The aromaticity index is based on data from experimentally determined bond lengths which yield statistically evaluated bond orders. A reasonable parallel exists between the aromaticity index and resonance energies <85T1409>. 

Bird aromaticity index (I) - An index of aromatic character based on a statistical evaluation of the extent of variation of ring bond orders compared to those of the nondelocalized Kekule structure. Bond orders are determined from experimentally determined bond lengths, or from accurate calculated values. The index was introduced for five-membered ring (7S) in 1985 by Clive Bird and subsequently extended to six-membered rings If) and bicyclic systems (7S,6 and 766). A universal index 7a unifies the approach (7a = 76 = 1.235 7s = 1.840 76,6 = 2.085 I tf) <1992T335>. For examples see Sections 2.24.2.3, 2.34.2.3, and 244.2.3. 

We have shown that the intrinsic electronic contribution to the Hammett substituent constant, cre(o>), may be obtained from a statistical analysis that follows from the comparison of the experimental <7p values and the electronic electrophilicity index co evaluated for isolated molecules.127 The analysis was performed for the electrophilicity of a series of substituted ethylenes, X-CH=CH2, and the crp values reported by Hansch et al.12S for a wide list of functional groups (FG), X-, commonly present in organic compounds. 

As the best available measure of classical aromaticity, Katritzky et al. commended the Bird 4 parameter, which is a new index of aromatic character based on a statistical evaluation of the deviations in peripheral bond orders <8511409, 86T89>, and is later improved to /a <92T335>. Unlike the resonance and aromatic energetical order, the Bird D or 7a estimates that pyrazine has a higher stability than pyridine and other diazines. 

Figure 5. The statistical evaluation of risk index (ir) is part of risk estimation step of risk assessment logic algorithm.

The ZOOM command is a powerful instrument for statistical evaluation in the ESA-IRS command language. Its task is to evaluate and display the occurrence of terms and Registry Numbers among Index Terms and controlled vocabulary, in order to define the next and optimized search step. 

The MEM and MEMSORT commands are powerful instruments for conducting crossfile searches including the World Patents Index and also statistical evaluations of search results. 

A homogeneity index or significance coefficienf has been proposed to describe area or spatial homogeneity characteristics of solids based on data evaluation using chemometrical tools, such as analysis of variance, regression models, statistics of stochastic processes (time series analysis) and multivariate data analysis (Singer and... 

We have recently evaluated the chlorendic imide/hindered phenol for its effect on the oxygen index of polyethylene, and we found only a miniscule increase, not considred statistically significant, in comparison to the same loading of chlorine as chlorendic anhydride. We believe that if the antioxidant approach to flame retardancy is to be successful, special high temperature antioxidant structures must be designed for this purpose. 

The comparison of the safety of equipment is not straightforward. It depends on several features of both process and equipment themselves. It can be evaluated from quantitative accident and failure data and from engineering practice and recommendations. Experience has been used for layout recommendations and for the development of safety analysis methods such as the Dow E F Index (Dow, 1987). Statistics contain details, causes and rates of failures of equipment and data on equipment involved in large losses. 

The chemical and most process factors affecting the index are quite straightforward to estimate. More problematic are the equipment safety and the safety of process structure. The equipment safety subindex was developed based on evaluation of accident statistics and layout information. The evaluation of the safe process structure subindex is based on case-based reasoning, which requires experience based information on accident cases and on the operation characteristics of different process configurations. 

Sulfur. Thiophene and benzo[ >] thiophene are both aromatic heterocycles, as discussed earlier in this review. Isothiazole is a planar molecule with an aromaticity comparable with those of thiazole and pyrazole, and higher than those of isoxazole and oxazole,122 140 as evaluated on the basis of Bird s aromaticity index A, based upon the statistical degree of uniformity of the bond orders of the ring periphery. Theoretical calculations and experimental data in connection with the aromaticity of isothiazole have been reviewed.141 Thiazole is also viewed as an aromatic molecule, similar to thiophene. It lacks an experimental aromaticity value, but the heat of formation together with bond lengths and angles have been calculated by various computational meth-... 

Calibration curve quality. Calibration curve quality is usually evaluated by statistical parameters, such as the correlation coefficient and standard error of estimate, and by empirical indexes, such as the length of the linear range. Using confidence band statistics, curve quality can be better described in terms of confidence band widths at several key concentrations. Other semi-quantitative indexes become redundant. Alternatively, the effects of curve quality can be incorporated into statements of sample analysis data quality. 

This was a multi-centre, pan-European, randomised double-blind placebo-controlled clinical trial in acute stroke to evaluate the effect of ancrod, a natural defribrinogenating agent (Hennerici et al. (2006)). The primary endpoint was based on the Barthel Index a favourable score of 95 or 100 or a return to the pre-stroke level at three months was viewed as a success. The primary method of statistical analysis was based on a logistic model including terms for treatment, age category, baseline Scandinavian Stroke Scale and centre. 

In practice, simpler though less reliable tests are used for evaluating the state of mixing. One of these involves calculating certain mixing indices that relate representative statistical parameters of the samples, such as the variance and mean, to the corresponding parameters of the binomial distribution. One such index is defined as follows ... 

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