The correlation comparison among body sway parameters from the gyroscope data sets

In the postural analysis, body sway parameters have been used to assess the steadiness of posturography in standing subject. The aim of this study was to compare correlations among ten different body sway parameters. We hypothesized that stronger correlations would exist in our system as corresponding to the conventional force plate method. The calibrated gyroscope sensor was attached to the subjects slightly under the navel. Of four healthy subjects, standing quietly on two legs with four different conditions (on a firm surface with opened eyes, on a firm surface with closed eyes, on a foam surface with opened eyes and on a foam surface with closed eyes), each condition was tested twice for 10 seconds. After calculating all parameters, we found the Pearson´s correlation coefficient among them. The ML (Medial-Lateral)amplitude showed the highest correlation coefficient (r = 0.660 at p <; 0.01). It means our measurement method is reliable and proper because normal human has body sway in the roll direction. In case of the correlation among ten parameters, the correlation coefficient between the convex hull area and the ellipse area was the highest correlation value (r = 0.986 at p <; 0.01). Therefore, the convex hull area is almost equal to the ellipse area.