Coefficient of variability

A recent interlaboratory comparison of HPLC and microbiological methods for total riboflavin revealed significant variability between the 13 participating laboratories (42). The extraction and hydrolysis of the riboflavin coenzymes were cited as the most likely sources of this variability. A later intercomparison (70) of riboflavin methods showed lower variability between laboratories, although coefficients of variability (CV) of 12-40% were still reported. 

Denotes coefficient of variables omitted by stepwise discriminant function analysis. 

The numbers in parentheses are the coefficients of variability of at least 7 recoveries. 

The assay can be considered reliable if the quality-control values lay within the accepted coefficient of variability. 

This procedure was used mainly to aehieve a reduction of dimensionality, i.e., to fit a A -dimensional subspace to the original / -variate observations p k). The statistics used to summarize the most important results was the percent of the total variation explained by the first k (usually two or three) components. In the case at hand the interpretation of PCA results was based on the diagrams of coefficients of variables (total concentrations of metals in the samples) and the scatter plot of samples (the stations separated in coastal, intermediate and offshore stations). 

The first step is to implement a Poisson model characterized by a mean with one interindividual variance term (see Model 1 in the appendix). The estimate of the population X was approximately 1.42 episodes per day with a 74% interindividual coefficient of variability (CV). Although not executed in the original analyses, for comparison purposes, a zero-inflated Poisson model was also evaluated (Model 2 in the appendix). The estimated probability of the nonsusceptible state was 0.342 (71% interindividual CV). The ZIP population X estimate was 2.33 (55% interindividual CV) episodes per day. Using the formulas given in Eq. (27.11) and (27.12), the population expectation (variance) was 1.53 (2.76) episodes per day. Note the overdispersion as indicated by the variance greater than the expected value. Figure 27.4 shows the predicted probability from the Poisson and the ZIP... 

From the two values, mean aperture and coefficient of variability, a screen test may be totally defined. Greater use of the Powers probability plot would eliminate confusion by buyers and sellers alike. 

Abstract The Canadian Nuclear Safety Commission (CNSC) used the finite element code FRACON to perform blind predictions of the FEBEX heater experiment. The FRACON code numerically solves the extended equations of Biot s poro-elasticity. The rock was assumed to be linearly elastic, however, the poro-elastic coefficients of variably saturated bentonite were expressed as functions of net stress and void ratio using the state surface equation obtained from suction-controlled oedometer tests. In this paper, we will summarize our approach and predictive results for the Thermo-Hydro-Mechanical response of the bentonite. It is shown that the model correctly predicts drying of the bentonite near the heaters and re-saturation near the rock interface. The evolution of temperature and the heater thermal output were reasonably well predicted by the model. The trends in the total stresses developed in the bentonite were also correctly predicted, however the absolute values were underestimated probably due to the neglect of pore pressure build-up in the rock mass. 

Also for phenolic resins it is not clear whether universally valid correlation equations will exist or if they will differ for different types of resins and boards, although the correlations obtained appear to have a lower coefficient of variability than for the aminoplastic resins. Nevertheless, it can be safely assumed that the various parameters used with at least be the same in most cases, even if the actual numerical values of the coefficients within the individual equations might differ. 

The coefficient of variability of the resulting fit was 0.7%. Usually A is zero, and a plot of C/T vs. is linear with intercept y (the electronic specific heat coefficient) and slope j8. A Debye temperature, do, can be extracted from the latter quantity using the numerical relationship... 

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