Fig. 4

a Stability evaluation calculated as the Euclidean distance between electrode corner digitizations at initial position and after 30 min—setup C (median 1.8 mm [white dot], inter-quartile range 1.5 mm [black box]), setup R (median 2.1 mm [white dot], inter-quartile range 1.8 mm [black box]). Distributions of n = 960 Euclidean distances from 4 corners of 4 stimulation electrodes measured on 20 volunteers, each in three sessions. b Reproducibility evaluation calculated as the Euclidean distance between the initial electrode corner digitizations aligned across sessions—setup C (median 2.8 mm [white dot], inter-quartile range 1.8 mm [black box]) setup R (median 9.0 mm [white dot], inter-quartile range 6.6 mm [black box]). Central black lines indicate 1.5 times the inter-quartile range (IQR). Distributions of n = 640 Euclidean distances from four corners of four stimulation electrodes measured on 20 volunteers for two placement repetitions (session 1–session 2, session 1–session 3)