Fig. 4
From: Diagnostic value of serum versus plasma phospho-tau for Alzheimer’s disease
Correlations and biases in paired serum vs. plasma p-tau concentrations. A–C Spearman correlation (rho) of serum vs. plasma p-tau concentrations in paired samples. The plots show correlations for p-tau181 in cohort 1 (A), p-tau231 in cohort 1 (B), and p-tau181 (using the commercial Quanterix kit) in cohort 2 (C). Bland-Altman plots for the same sample pairs are shown in D–F, respectively. The y-axes display the individual differences (serum subtracted from plasma)/average of the two, whereas the x-axes display the mean of the two. For each plot, the top and bottom horizontal lines show the 95% limit of agreement while the middle horizontal line shows the estimated bias