Fig. 2 exhibits some results obtained from the exploratory principal components analysis. Regarding the variations covered by the first two principal components (PC1 and PC2), one can see from Fig. 2(a) that PC1 explains most of the variation in the data (96.8%); it indicates the high level of dependence between the bins as well as the goodness-of-fit of PC1 to capture such dependence. In turn, two samples from the non-irradiated group were considered