Fig. 7

Graphical representation of manual measurement reproducibility and absolute operator-induced error. a Bland-Altman and 4 quartiles box plots of absolute errors on ProjA values. b Bland-Altman and 4 quartiles box plots of absolute errors on SafA values. Bland-Altman plots are used to represent the difference between each measurement and the gold standard (GS) on the y axis. If perfect agreement between the 2 compared methods was present, all the points would be located on the 0 line. The 2 lines parallel to the 0 line represent the 95 % tolerance limits which is the expected error on a single measurement with respect to the gold standard with 95 % probablity