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. Author manuscript; available in PMC: 2018 Dec 29.
Published in final edited form as: J Biomech. 2016 Dec 1;53:1–8. doi: 10.1016/j.jbiomech.2016.11.059

Figure 4:

Figure 4:

Stride variabilities and covariances. (A.) Individual stride deviations (dots, colors denote different subjects) and associated covariances ellipses for forward placement, lateral placement, external rotation, and combinations thereof, for each subject (thin ellipses) and for all subjects and strides together (thick ellipse), for both Young (N =15) and Elderly (N =11)subjects. (B.) Significance of covariances, (left to right:) Root-mean-square (RMS) variability for each measure (square root of each diagonal of covariance matrix); Covariance for off-diagonal terms; Coupling angle between measures, defined as angle of covariance axis. Data are shown for Young (N =15) and Elderly (N =11)subjects, with error bars denoting standard deviations across subjects. Significant covariances (differing from zero, p < 0.01) are denoted with asterisks. Significant covariance was observed between external foot rotation and lateral foot placement for both subject groups.