Figure 3
From: Pooling samples for “top-down” molecular exposomics research: the methodology
When the random grouping numbers of pools risen to eight, the expected frequency of non-significant difference between the case and control for some arsenic species reached down to the value of that the difference calculated by individual data*. The pool numbers (i.e., numbers of pools in x-axis) was set as 2, 3, 4, 5 and 8 and coded as G2, G3, G4, G5 and G8; n = 157, 140, and 151 for the case-1, case-2 and control subjects (Table 2); 100 times random grouping was applied to the populations; AsV: arsenate; As: the total arsenic; MMA: methylarsonic acid; AsIII: arsenite; DMA: dimethylarsinic acid; AsB: arsenobetaine. *For the upper mentioned bio-monitoring data can not be normalized by logarithmic transformation, calculated differences by using >5 random pool means of the case and control, respectively, may be close to by using the individual data.