Table 2.
Analysis of the computed features from the displacement of the COP.
| Young Adult (Groups 1 and 2) | Elderly Adult (Groups 6 and 7) | ANOVA p-value | Correlation with age | Correlation Groups | |||||
|---|---|---|---|---|---|---|---|---|---|
| Features | OE | CE | OE | CE | OE | CE | OE | CE | |
| Mean Velocity | 6.15 | 9.45 | 8.27 | 14.52 | < | r = 0.3 | r = 0.28 | ||
| Ap (mm/s) * | ± 1.32 | ± 3.08 | ± 3.69 | ± 10.74 | 0.03 | A | |||
| Mean Velocity | 5.40 | 7.54 | 7.14 | 12.91 | < | < | r = 0.25 | r = 0.29 | |
| Ml (mm/s) * | ± 1.05 | ± 2.77 | ± 3.35 | ± 9.15 | 0.04 | 0.02 | B | ||
| Mean Velocity | 9.11 | 13.45 | 12.12 | 21.55 | < | < | r = 0.29 | r = 0.29 | |
| RD (mm/s) * | ± 1.59 | ± 4.05 | ± 5.43 | ± 15.63 | 0.03 | 0.04 | C | ||
| Range | 21.10 | 27.84 | 18.62 | 27.90 | r = -0.03 | r = -0.07 | |||
| Ap (mm) | ± 5.57 | ± 8.03 | ± 4.74 | ± 10.80 | D | ||||
| Range | 19.80 | 21.59 | 20.37 | 24.53 | r = -0.05 | r = 0.02 | |||
| Ml (mm) | ± 6.40 | ± 7.32 | ± 7.98 | ± 10.43 | E | ||||
| Displacement | 230.6 | 320.0 | 299.3 | 500.2 | < | < | r = 0.27 | r = 0.28 | |
| Ap (mm) * | ± 47.7 | ± 90.7 | ± 118.8 | ± 369.2 | 0.03 | 0.05 | A | ||
| Displacement | 171.4 | 235.8 | 229.4 | 414.7 | < | < | r = 0.28 | r = 0.3 | |
| Ml (mm) * | ± 30.8 | ± 81.6 | ± 102.1 | ± 300.6 | 0.03 | 0.02 | B | ||
| Displacement | 273.4 | 403.6 | 363.7 | 646.7 | < | < | r = 0.29 | r = 0.29 | |
| RD (mm) * | ± 47.6 | ± 121.4 | ± 163.0 | ± 469.2 | 0.03 | 0.04 | C | ||
| RMS | 4.52 | 5.74 | 3.60 | 4.91 | r = 0.42 | r = 0.48 | |||
| Ap (mm) | ± 1.52 | ± 1.82 | ± 0.94 | ± 1.95 | p < 0.01 | p < 0.001 | F | ||
| RMS | 4.04 | 4.27 | 3.79 | 4.57 | r = 0.33 | r = 0.44 | |||
| Ml (mm) | ± 1.39 | ± 1.47 | ± 1.22 | ± 1.82 | p < 0.001 | G | |||
| Mean Freq. | 0.21 | 0.25 | 0.33 | 0.42 | < | < | r = 0.41 | r = 0.51 | |
| Ap (Hz) * | ± 0.06 | ± 0.07 | ± 0.16 | ± 0.19 | 0.01 | 0.001 | p < 0.01 | p < 0.001 | F, H |
| Mean Freq. | 0.22 | 0.28 | 0.30 | 0.41 | < | < | r = 0.34 | r = 0.46 | |
| Ml (Hz) * | ± 0.07 | ± 0.06 | ± 0.08 | ± 0.12 | 0.01 | 0.001 | p < 0.01 | p < 0.001 | G, I |
| Peak Freq. | 0.05 | 0.08 | 0.09 | 0.19 | r = 0.27 | r = 0.28 | |||
| Ap (Hz) | ± 0.03 | ± 0.06 | ± 0.07 | ± 0.24 | |||||
| Peak Freq. | 0.06 | 0.10 | 0.07 | 0.15 | r = 0.13 | r = 0.25 | |||
| Ml (Hz) | ± 0.03 | ± 0.07 | ± 0.05 | ± 0.09 | |||||
| F50 | 0.083 | 0.13 | 0.20 | 0.27 | < | < | r = 0.43 | r = 0.48 | |
| Ap (Hz) * | ± 0.03 | ± 0.05 | ± 0.14 | ± 0.18 | 0.01 | 0.01 | p < 0.001 | p < 0.001 | H |
| F50 | 0.11 | 0.16 | 0.17 | 0.28 | < | < | r = 0.28 | r = 0.45 | |
| Ml (Hz) * | ± 0.05 | ± 0.05 | ± 0.10 | ± 0.12 | 0.04 | 0.001 | p < 0.001 | I | |
| F80 | 0.25 | 0.34 | 0.46 | 0.63 | < | < | r = -0.29 | r = -0.22 | |
| Ap (Hz) * | ± 0.11 | ± 0.12 | ± 0.26 | ± 0.33 | 0.01 | 0.001 | D | ||
| F80 | 0.30 | 0.36 | 0.40 | 0.59 | < | < | r = -0.14 | r = -0.05 | |
| Ml (Hz) * | ± 0.11 | ± 0.08 | ± 0.14 | ± 0.23 | 0.03 | 0.001 | E | ||
| Total Power | 23.99 | 38.40 | 14.35 | 28.14 | r = -0.28 | r = -0.2 | |||
| Ap | ± 17.88 | ± 25.04 | ± 7.44 | ± 23.95 | D | ||||
| Total Power | 19.20 | 21.44 | 16.44 | 24.57 | r = -0.16 | r = -0.05 | |||
| Ml | ± 12.80 | ± 14.53 | ± 10.54 | ± 19.45 | E | ||||
| Conf. Ellipse | 223.0 | 325.5 | 172.6 | 305.3 | r = -0.23 | r = -0.14 | |||
| area (mm2) | ± 128.9 | ± 210.4 | ± 93.0 | ± 249.5 | J | ||||
| Conf. Ellipse | 10.77 | 12.29 | 8.79 | 11.02 | r = -0.31 | r = -0.2 | |||
| major axis (mm) | ± 3.29 | ± 3.69 | ± 2.48 | ± 4.11 | D, J | ||||
| Conf. Ellipse | 1.97 | 1.78 | 2.16 | 2.20 | < | r = 0.09 | r = 0.31 | ||
| angle (rad)* | ± 0.38 | ± 0.36 | ± 0.58 | ± 0.40 | 0.01 | ||||
| SDA - Ds | 0.13 | 0.33 | 0.21 | 0.69 | r = 0.21 | r = 0.24 | |||
| Ap | ± 0.06 | ± 0.21 | ± 0.18 | ± 0.89 | A | ||||
| SDA - Ds | 0.12 | 0.23 | 0.21 | 0.58 | < | < | r = 0.26 | r = 0.3 | |
| Ml * | ± 0.04 | ± 0.16 | ± 0.17 | ± 0.57 | 0.04 | 0.01 | B | ||
| SDA - Dl | 0.05 | 0.05 | 0.02 | 0.02 | < | r = -0.27 | r = -0.23 | ||
| Ap * | ± 0.04 | ± 0.05 | ± 0.02 | ± 0.04 | 0.04 | ||||
| SDA - Dl | 0.03 | 0.02 | 0.02 | 0.02 | r = -0.16 | r = -0.09 | |||
| Ml | ± 0.02 | ± 0.03 | ± 0.02 | ± 0.02 | |||||
| SDA - Hs | 1.81 | 1.78 | 1.74 | 1.76 | < | r = -0.31 | r = -0.16 | ||
| Ap * | ± 0.06 | ± 0.04 | ± 0.08 | ± 0.06 | 0.01 | ||||
| SDA - Hs | 1.80 | 1.77 | 1.77 | 1.78 | r = -0.11 | r = 0.03 | |||
| Ml | ± 0.05 | ± 0.05 | ± 0.05 | ± 0.06 | |||||
| SDA - Hl | 0.64 | 0.44 | 0.32 | 0.23 | < | < | r = -0.44 | r = -0.44 | |
| Ap * | ± 0.22 | ± 0.19 | ± 0.24 | ± 0.17 | 0.001 | 0.01 | p < 0.001 | p < 0.001 | |
| SDA - Hl | 0.44 | 0.30 | 0.33 | 0.21 | r = -0.23 | r = -0.18 | |||
| Ml | ± 0.20 | ± 0.13 | ± 0.17 | ± 0.13 | |||||
| SDA-critical time | 1.08 | 1.31 | 1.04 | 0.95 | < | r = -0.1 | r = -0.38 | ||
| Ap (s) * | ± 0.51 | ± 0.31 | ± 0.41 | ± 0.42 | 0.01 | p < 0.01 | |||
| SDA-critical time | 1.43 | 1.28 | 1.25 | 0.98 | < | r = -0.19 | r = -0.38 | ||
| Ml (s) * | ± 0.78 | ± 0.33 | ± 0.32 | ± 0.27 | 0.01 | p < 0.01 | |||
| SDA (mm2) | 0.16 | 0.41 | 0.17 | 0.43 | r = -0.03 | r = -0.02 | |||
| critical mag.-Ap | ± 0.14 | ± 0.27 | ± 0.09 | ± 0.31 | |||||
| SDA (mm2) | 0.21 | 0.30 | 0.21 | 0.38 | r = -0.08 | r = 0.01 | |||
| critical mag.-Ml | ± 0.18 | ± 0.22 | ± 0.13 | ± 0.27 | |||||
| DFA - α | 1.43 | 1.57 | 1.49 | 1.62 | r = 0.16 | r = 0.12 | |||
| Ap | ± 0.09 | ± 0.09 | ± 0.13 | ± 0.16 | |||||
| DFA - α | 1.72 | 1.78 | 1.70 | 1.81 | r = -0.09 | r = 0.01 | |||
| Ml | ± 0.06 | ± 0.09 | ± 0.12 | ± 0.12 | |||||
| HR/S | 0.97 | 1.01 | 0.99 | 1.02 | r = 0.2 | r = 0.04 | |||
| Ap | ± 0.04 | ± 0.02 | ± 0.03 | ± 0.02 | |||||
| HR/S | 1.03 | 1.03 | 1.02 | 1.03 | r = -0.09 | r = -0.01 | |||
| Ml | ± 0.004 | ± 0.005 | ± 0.01 | ± 0.01 | |||||
| ApEn | 0.008 | 0.008 | 0.010 | 0.012 | < | < | r = 0.24 | r = 0.43 | |
| Ap * | ± 0.002 | ± 0.002 | ± 0.003 | ± 0.005 | 0.05 | 0.01 | p < 0.001 | ||
| ApEn | 0.007 | 0.009 | 0.008 | 0.011 | < | r = 0.14 | r = 0.29 | ||
| Ml * | ± 0.002 | ± 0.002 | ± 0.002 | ± 0.003 | 0.01 | ||||
Note that OE is the experimental condition of opened eyes whereas CE is the closed eyes. The mean and standard deviation are presented for each feature. Features that presented a significant difference between the groups are highlighted with '*' and in this case the estimated p-value of the ANOVA is shown. The correlation between the age and the feature is also presented. In the last column we present the analysis of the correlation between the studied features. When a correlation coefficient larger than 0.9 was found the features were included in the same group labeled by letters A, B, C, D, E, F, G, H, I, J.