BACKGROUND: Focusing on the efficiency aspect of computer pointing devices’ usability, this paper reports on a novel and tentative empirically derived efficiency index for 3D CAD.

OBJECTIVE: Three commercially available computer pointing devices were compared: a standard horizontal computer mouse, a vertical device (supporting neutral pronation of the forearm) and a slanted device.

METHODS: Pilot structured observations of 10 subjects’ activity were carried out to estimate the proportion of each unique computer mouse operation during CAD modelling with a 3D parametric software. Pointing, dragging and steering standardized tasks were implemented by software and performed by 20 users. Effectiveness and efficiency were calculated and discomfort, effort and ease of use were subjectively assessed.

RESULTS: The mean efficiency index value was lower for the vertical device. Assessments of discomfort, effort and ease of use also supported considering preference for the horizontal and slanted devices, providing limited internal validation.

CONCLUSION: Results suggest the tentative index may offer a valid means of ranking performance of alternative pointing devices regarding operation efficiency.