Table 1 Example measures of surgical expertise/performance. Note that definitions may vary slightly across studies and measurements must be considered with relevance to the task

Idle time [20]

Length of time in which there is little movement in both hands.

May represent periods devoted to action planning or decision-making. Shorter periods of idle time are linked with higher expertise.

Working volume [21]

Area of space occupied by hands whilst completing a task.

Measure of efficiency with lower working volume linked with higher expertise.

Path length [22, 23, 25]

The length of the trajectory that the hand travels in a given task.

Measure of efficiency. Relative to tissue and task expertise. May be linked with either shorter or longer path lengths [25].

Task completion time [24,25,26]

Time taken to complete a task.

Measure of efficiency with faster completion times linked with higher expertise.

Number of movements [24, 26, 27]

Number of movements used to complete a given task, sometimes within a given time.

Measure of efficiency with fewer movements linked with higher expertise.

Rate of change in tool orientation [25]

The speed at which the tool angle changes during movement.

Faster rates of change linked with expertise.

Velocity [23]

Displacement over time

Higher velocity linked with expertise.

Acceleration [23]

Velocity over time

Lower acceleration linked with expertise; higher acceleration may reflect attempts to make up for slower action overall.

Smoothness [28]

Acceleration over time

Increased smoothness linked with the expertise. Reflective of better action planning and execution.