Rank-order correlation

IVIVCs can be divided into non-quantitative and quantitative. In non-quantitative correlations the two variables are not related to each other via a mathematical relationship. A characteristic example is the rank-order correlation that was popular in the 1970s (10-15). In quantitative correlations the in vitro variable correlates with the in vivo variable via a linear or a non-linear equation. A quantitative IVIVC can be established, with or without the framework of a model, by using estimated values of characteristic parameters of the in vitro dissolution process and estimated values of the characteristic parameters of the in vivo arrival-in-bloodstream... 

Rank order correlations are qualitative and are not considered useful for regulatory purposes. 

FIGURE 26.2 Spearman ranking order correlation between time to peak heat release rate (TTPHRR) and single wire burn. (From Cogen, J.M. et al., Assessment of flame retardancy in polyolefin-based non-halogen FR compounds, In Proceedings of the 53rd IWCS/Focus International Wire and Cable Symposium, 2004, pp. 185-190.)... 

The 28 toxoplasma-positive sera that had been titrated for antibody by FA were titrated by RIA, and the titers of the two tests were correlated, using Spearman s rank-order correlation test. The correlation coefficient was 0.68, and probability that this value differs from zero (no correlation) by chance alone was <0.001. Thus there was reasonably good agreement between the titers obtained in the two tests. 

If correlation analysis is used with the raw data, ideally both data types should have similar ranges and distributions. If data is directly linearly correlated, this can be neglected, but is rarely the case for metabolome and transcriptome data. Changes in gene expression may not alter metabolite pools significantly. Therefore, data have to be normalized in an appropriate way and correlation methods other than linear correlation have to be used (e.g., Spearman s rank-order correlation or Kendall rank correlation should be preferred over Pearson correlation). 

These automated assays can be used for high-throughput ADME screening in early drug discovery. The double-sink PAMPA permeability assay mimics in vivo conditions by the use of a chemical sink in the acceptor wells and pH gradient in the donor wells. The use of the pION gut-box integrated on the deck has shortened the PAMPA assay incubation time to 30 minutes. The permeability coefficient and rank order correlate well with data obtained using the in vitro Caco-2 assay and in vivo permeability properties measured in rat intestinal perfusions. 

The Spearman rank-order correlation coefficients for the various parameters are ... 

One-way analysis of variance (ANOVA) was used for assessment of the differences among groups and subgroups of subjects. Spearman s rank order correlations were used for analyses of the relationships between isoflavones and thyroid hormone parameters. 

Factor 3 had the highest loadings on Ni and V which have been reported as tracers of petrochemical industry and oil combustion (Moreno et al. 2006a Meza-Figueroa et al. 2007 Salvador et al. 2007 Viana et al. 2007). The same link was identified by PCA at each sampling site with the exception of Simcoe and Toronto where, unlike the other sites, there was no correlation between these elements (Spearman Rank Order Correlations less than 0.5). The Abbotsford,... 

Table 9.2 is an example of "perfect rank-order" and "imperfect rank-order" correlations. 

Table 9.2 Examples of perfect and imperfect rank order correlations ...

We analyzed many of these pulps by IGC to determine if there was an increase in donor or acceptor character for the pulp or if the dispersive energy characteristics of the pulp were changed in a manner that correlates to the methylene blue binding result. Table II shows the surface acid-base characteristics and dispersive component for these pulps. The ability to act as a Lewis acid was the only statistically significant correlation when compared with methylene blue binding, with rs = -0.56 (Spearman rank-order correlation coefficient) and P = 0.03. The ability to act as a Lewis base, the dispersive component, and the ratio of acid to base had no relationship with methylene blue binding. 

For the statistical analysis, the results for each test specimen were coded either one for a pass (i.e., no liquid penetration) or zero for a failure. The effects of fabric type and challenge liquid on the liquid penetration of the fabrics were analyzed using separate two-way analyses of variance, Fisher s LSD post hoc comparison tests, and Spearman s rank order correlations. The level of statistical significance was set at 0.05. The statistical tables and raw data are available in the technical report (8). 

In addition, we examined to which extent the three groups differ in means on each competence, both phases together, visually and with an analysis of variance (ANOVA). We also calculated rank order correlations between the variable time and the competence ratings for each group to investigate the differences in progression, separately for two phases in OJT. 

Table 3.6 Rank order correlations (Spearman) between time and competence ratings for learning phases 1 and 2...

Rank order correlations (Spearman) between time and... 

The accelerated weathering task group members reevaluated their analysis method. They determined that rank-order correlation between the outdoor and accelerated tests was less important than whether the accelerated test method accurately predicted which samples would pass outdoor testing and which would fail. In an effort to determine this, threshold maximum EVs were used in subsequent testing. 

Several authors have noted a relationship between the lipophilicity of the solubilizate, expressed as its partition coefficient between octanol and water, Pocianob its Saturation distribution between micelles and the aqueous phase. Rank-order correlations between the amount of substituted barbituric acid solubilized by polyoxyethylene stearates and their Poctanoi values have been reported by Ismail et al. [133]. Similarly the partition coefficients of several steroids between water and micelles of long-chain polyoxyethylene non-ionic surfactants have been correlated with their ether/water partition coefficients [145], Fig. 5.18 shows a linear relationship between the partition coefficient of a... 

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