Fig. 3.

Intra-observer variability in repeated measurements. (A) Maximum protraction; (B) maximum retraction; (C) maximum abduction; (D) maximum adduction. Maximum excursion is influenced by the force applied by observers. Note small standard deviation (black error bars) within the repeated measurements performed by P.A. All subsequent manipulations were performed exclusively by P.A. to avoid potential confounding inter-observer variability.