Regression coefficient plots

Figure 7.2.13. Regression coefficient plots for PLS calibrations of Brix value (solid Une) and...

It is also interesting to examine the actual regression coefficients that each calibration produces. Recall that we get one row in the calibration matrix, K, for each component that is predicted. Each row contains one coefficient for each wavelength. Thus, we can conveniently plot each row of as if it were a spectrum. Figure 21 contains a set of such plots for each component for Klu, and K2 . We can think of these as plots of the "strategy" of the calibration... 

Both aspects are combined in Fig. (2.20) and Table 2.16, where the linear coordinates are x resp. y, the logarithmic ones , resp. v. Regression coefficients established for the lin/lin plot are a, b, whereas those for the transformed coordinates are p, q. 

Linear regression coefficients should be calculated for the ratio of analyte to internal standard area or height plotted versus the ratio of analyte to internal standard concentration in the calibration standards. The data from the analytical standards should then be fitted to the linear model... 

In Figure 7.3, the partition coefficients, their ratio, the correlation of the response surfaces and the variances of the partition coefficients and the ratio are plotted for extraction of two compounds i and j into a binary extraction liquid. The regression coefficients / , P i for P and P2... 

As a calibration procedure in ICP-MS via calibration curves, external calibration is usually applied whereby the blank solution is measured followed by a set of standard solutions with different analyte concentrations (at least three, and it is better to analyze more standard solutions in the same concentration range compared to the sample). After the mass spectrometric measurements of standard solutions, the calibration curve is created as a plot of ion intensities of analyte measured as a function of its concentration, and the linear regression line and the regression coefficient are calculated. As an example of an external calibration, the calibration curve of 239 Pu+ measured by ICP-SFMS with a shielded torch in the pgC1 range is illustrated in Figure 6.15. A regression... 

If plotting cannot be used in the selection of a proper geometric representation (and the corresponding equation form) of the Influence of each variable factor being studied, then accepted theory and past research results may aid the researcher in selection of variable and equation forms to be used. Within limits, the resuts of t-tests of regression coefficients may be used to select the most appropriate variables and variable transformations for use in the final... 

Using logarithmic paper, plot XIM (as the ordinate) versus C (as the abscissa) for each of the three carbon dosages. Calculate the least squares fit for the three points, and plot. The iodine number is the XIM value at a residual iodine concentration (C) of 0.02 N. The regression coefficient for the least squares fit should be greater than 0.995. 

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