Table 1.

The average ICC and RMSE values for the Head movements recorded from the Qualisys and the Oculus Quest systems. The values are for the three axes (ML, AP and Vertical) and the calculated distance (sway) are presented for the three different stances (Double, Tandem, Single). ICC values can be interpreted as follows: ICC > 0.8 is excellent; ICC < 0.8 > 0.6 is good; ICC < 0.6 > 0.4 is moderate, while ICC < 0.4 is poor [19]. RMSE values are measured in mm with values closest to 0.0 indicating the highest levels of precision.

	Oculus vs. Qualisys Head Movement
Stance	ICC				RMSE (mm)
	ML	AP	Vertical	Distance	ML	AP	Vertical	Distance
Double	0.877	0.983	0.978	0.936	4.2	1.3	3.3	3.8
Tandem	0.994	0.996	0.937	0.994	3.4	4.2	1.6	3.9
Single	0.990	0.998	0.994	0.998	3.9	4.3	4.4	4.7