Fig. 4

Bland–Altman plot. The average immunoglobulin G (IgG) concentrations measured by radial immunodiffusion (RID) and ATR methods (x-axis) against the difference in IgG concentrations between the two methods (y-axis) for the prediction set samples (n = 67). The dashed lines represent the 95 % confidence limits of agreement (–670 to 611 mg/dL) and the solid line represents the mean difference between ATR and RID assays (-30 mg/dL), indicating no appreciable systematic difference between the two methods