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Table 1 Technical properties of different existing smoothness measures

From: On the analysis of movement smoothness

Measure

Validity

Sensitivity

Reliability

Practicality

 

D

M1

M2

 

Measurement noise

 

Root mean square jerk

×

-

-

-

-

✓

Normalized mean absolute jerk

×

-

-

-

-

✓

Dimensionless jerk

✓

✓

✓

×

×

✓

Log dimensionless jerk

✓

✓

✓

✓

×

✓

No. of peaks

✓

✓

✓

×

×

✓

Speed arc length

✓

✓

✓

✓

×

✓

Spectral arc length

      

(SAL introduced in [4])

×

✓

✓

✓

✓

✓

Spectral arc length

      

(SPARC introduced in this paper)

✓

✓

✓

✓

✓

✓

  1. D - Dimensionless; M1 - Monotonic response to changes in submovement interval; M2 - Monotonic response to changes in number of sub-movements. (× means the measure does not satisfy this property, \(\checkmark \) indicates that it does satisfy the property. − indicates that information about this property is not available)