Analytical Results and Chemometric Evaluation

Whereas application of LMS regression (Eq. 9-5) results in considerable improvement of the rank correlation coefficients, the correlation coefficients obtained by RLS regression (with outlier elimination Eq. 9-6) are again markedly lower. 

Plant lead content/soil lead content 0.3013 0.7434 0.5473 

Plant lead content/distance from the road -0.3839 -0.7788 -0.4014 

The coefficient of the LMS regression function for the relationship between plant and soil lead content, ao soii = 0.90 mg kg 1 Pb, corresponds to the median amount of lead taken up by the plants from atmospheric emissions if the soil lead content were zero, 

It is obvious that LS regression yields values that are too high and cannot be used for interpretation of plant lead content. The introduction of the reweighted median-related values enables comparison of the results of the various LMS regressions with one another. For this purpose the regression coefficient a7/ of the function 

---