Fig. 2

a-d Bland Altman analysis of the balance measurement instruments to visualize differences between (a) GVMBT and the BBS and (c) GVMBT and TUG. Bland Altman plots of the balance MIs and corresponding scatter plots. BA plots describe the agreement between two methods: a GVMBT and BBS; c GVMBT and TUG, where the difference is plotted against the mean. The solid line reveals the bias and the dashed lines represent the upper and lower limits of agreement as bias ± 1.96 standard deviation. Scatter plots show the relationship between the balance MIs: b GVMBT and BBS; d GVMBT and TUG. The regression equation is expressed as: y = a (95% CI) + b (95% CI) x. The correlation coefficient with its 95%CI between the GVMBT and the BBS is rs = 0.93 (0.88;0.96) and between the GVMBT and the TUG is rs = − 0.85 (− 0.91;-0.75)