Table 4.

Primitive-level classification using IMU or accelerometer data.

Primitives	Classification performance (PPV)
	IMU	Accelerometer
Reach	93%	77%
Transport	91%	80%
Reposition	93%	82%
Idle	92%	88%
Average	92.5%	82%

Classification performance is shown using the 7-sensor configuration (pelvis, sternum, head, and the active shoulder, upper arm, forearm, and hand). Accelerometers provided systematically poorer classification performance compared to IMUs across all primitives. Classification performance using accelerometry data was particularly low for reach (PPV 77%) and relatively higher for idle (PPV 88%).