TABLE 2. Endoscope Motion Tracker Position Calibration. All Uncertainty Values are Quoted at One Standard Deviation.

	Bottom Trackball	Top Trackball	Reconciled Position
Counts per ± 50 mm (% Uncertainty)	413 ± 27 (6.5 %)	403 ± 21 (5.1 %)	419 ± 12 (2.9 %)
Linear Distance in mm per Count	0.121 ± 0.008 mm	0.124 ± 0.006 mm	0.119 ± 0.003 mm