Figure 7:

Error (ϵ) (difference) between manual FHR ($h_m^f$) and automatic FHR ($h_a^f$) of the LHU validation set. Shaded area shows the 10% PPA bounds (error no greater than 10 percent of the $h_m^f$). N stands for the number of segments in the validation set, and in parenthesis is the percentage of segment satisfying the PPA. The red line is the robust least square fit of ϵ along the manual FHR estimations ($ϵ=-0.571+0.04h_m^f;r^2=0.99$).