Figure 3. (a) TT4 and (b) TT3 Between-Method Variability. The figure shows the variability among 11 TT4 (A-P) and 12 TT3 (A-M) methods (shown as assay means 2 sd) relative to the RMP for the method. For the assays differing >10% from the RMP mean, the numerical value of the mean is listed (28).