Figure 6. A box and whisker plot showing the root mean squared error (RMSE) of the Leave One Subject Out (LOSO) validation, using the previously selected hyperparameters for $\mathit{G}R{F}_{ap}$ estimation.

The solid line within each box represents the median error across all foot contacts, the box spans from the 25th to the 75th percentile (interquartile range), and the whiskers encompass $1.5\times$ the interquartile range. The participants included in the hyperparameter optimisation process are shown in the left section of the graph, those not included are shown in the right section.