Fig 1.
Typical ways of visualizing trajectories of the CoP.
(a) statokinesigram and (b) AP and ML stabilograms.
Fig 2.
Schematic representing the elements used to approximate curvature values.
The blue curved line represents the trajectory, γ(ti−1…i+1) are the involved points to estimate the curvature value at the γ(ti) point, a, b and c are the sides of the triangle, the dotted line is the fitted circle, and R is its radius.
Fig 3.
Heat map visualizing 400 CoP ML stabilograms.
The horizontal axis represents trials per participant, with participants ordered by age. The vertical axis represents time from 6 to 26 seconds. The color-shaded vertical lines represent the CoP medial lateral position per trial.
Fig 4.
Violin plots representing CoP ML transitions between feet.
The horizontal axis represents the distribution of CoP ML measurements per participant as violin plots, and the vertical axis represents the CoP ML coordinate. This figure appeared in [54]. Eurographics Proceedings 2016. Reproduced by kind permission of the Eurographics Association.
Fig 5.
Heat map visualization of measures by trial and participant.
The horizontal axis represents trials, as vertical lines, per participant, with participants ordered by age; the vertical axis represents our measures of balance (—mean curvature, κ—median curvature, “′” represents a variant of the measure, I—turbulence intensity, CoV coefficient of variation, RMS—root mean square, SD—standard deviation), and shades of “red” indicate higher and lower values for measures of balance. This figure appeared in [54]. Eurographics Proceedings 2016. Reproduced by kind permission of the Eurographics Association.
Fig 6.
Overlapping violin plots showing differences between older and younger participants.
The three values above each pair of overlapping violin plots are the overlapping area (OVL), the U-statistic and the p-values. The t-test results for κ are in the main text.
Fig 7.
Normalized measures as a parallel coordinate plot.
In the box plots points beyond the whiskers are outliers as specified by [62].
Fig 8.
Biplot and projection of the balance measures onto the first two principal components PC1 and PC2.
The arrows represent the variable vectors and the ellipses cluster older and younger participants. This figure was adapted from [54]. Eurographics Proceedings 2016. Reproduced by kind permission of the Eurographics Association.
Fig 9.
Contribution of the variables to the first two PCs.
The horizontal axis represents the variables and the vertical axis represents the percentage of contribution. The green dashed line represents the mean contribution of the variables (100/11).
Fig 10.
Correlation and scatterplot matrix.
Lower triangular matrix: scatterplot matrix, to maintain a good aspect ratio of the plots, values larger than 3.4 from the normalized data (2.5%) were excluded (only for visualization purposes). To estimate the correlation coefficients all data were used. Each point represents a single trajectory. Upper triangular matrix: Pearson correlation matrix. Larger font size indicates stronger correlation, either positive or negative. Absolute correlation values smaller than 0.21 are not significant.