Error improvements by the NS as a function of recorded torso movement amplitudes. The RMSE improvement by NS was defined as RMSEMS –RMSENS. Recorded torso movement amplitude was defined as max – min angle. A: Flexion/extension, B: Axial rotation, and C: Lateral bending. Error bars indicate 95th percentile confidence intervals. 25%, 50%, 75%, and 100% denote 25th, 50th, 75th, and 100th percentile torso movement amplitudes, respectively.