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# Table 1 Overview of Smoothness metrics identified from the literature

From: Smoothness metrics for reaching performance after stroke. Part 1: which one to choose?

Metric (Abbreviation) | Units |
Articles used^{a}
| Exclusions | Category | Earliest citation |
---|---|---|---|---|---|

Index of curvature (IC) | [] | 1 | E3 | Trajectory | [33] |

Standard deviation in 2D plane (SD_XY) | [] | 1 | E3 | Trajectory | [72] |

Number of sub-movements (NOS) | [] | 1 | Velocity | [37] | |

Speed metric (SM) | [] | 15 | Velocity | [14] | |

Normalized reaching speed (NRS) | [] | 2 |
E4 (SM)
| Velocity | [35] |

Movement arrest period ratio (MAPR) | [] | 3 | Velocity | [34] | |

Tent Metric (TM) | [] | 1 | E2 | Velocity | [14] |

Velocity Arc Length (VAL) | [] | 1 | Velocity | [4] | |

Correlation Metric (CM) | [] | 2 | Velocity | [38] | |

Peaks Metric (Peaks) | [] | 61 | Acceleration | [39] | |

Number of Movement Units (NMU) | [] | 3 |
E4a (Peaks)
| Acceleration | [73] |

Number of peaks normalized by movement duration (NPt) |
[s^{−1}]
| 1 | E1 | Acceleration | [40] |

Number of peaks normalized by movement distance (NPd) |
[m^{−1}]
| 3 | E1 | Acceleration | [41] |

Inverse number of peaks and valleys (IPV) | [] | 1 | Acceleration | [44] | |

Acceleration metric (AM) | [] | 2 | E1 | Acceleration | [35] |

Integrated absolute jerk (IAJ) |
[ms^{−2}]
| 2 | E1 | Jerk | [74] |

Mean absolute jerk (MAJ) |
[ms^{−3}]
| 2 | E1 | Jerk | [33] |

Mean absolute jerk normalized by peak speed (MAJPS) |
[s^{−2}]
| 7 | E1 | Jerk | [14] |

Integrated squared jerk (ISJ) |
[m^{2}s^{−5}]
| 1 | E1 | Jerk | [75] |

Root mean squared jerk metric (RMSJ) |
[ms^{−3}]
| 1 | E1 | Jerk | [76] |

Normalized integrated jerk (NIJ) |
[ms^{−3} \(\sqrt{\mathrm{s}}\)]
| 1 | E1 | Jerk | [77] |

Dimensionless squared jerk (DSJt) | [] | 12 | Jerk | [3] | |

Log dimensionless squared jerk (LDSJt) | [] | 1 | Jerk | [5] | |

Dimensionless squared jerk (DSJm) | [] | 1 |
E4a (DSJt)
| Jerk | [2] |

Dimensionless squared jerk (DSJb) | [] | 1 | Jerk | [4] | |

Log dimensionless squared jerk (LDSJb) | [] | 1 | Jerk | [4] | |

Rotational jerk (RJ) | [] | 1 | E3 | Jerk | [48] |

Spectral metric (SPMR) | [] | 1 | Frequency | [49] | |

Spectral method (SPM) | [] | 1 | Frequency | [1] | |

Spectral arc length 2012 (SPAL) | [] | 8 | Frequency | [4] | |

Spectral arc length (SPARC) | [] | 1 | Frequency | [6] | |

Combined smoothness metric (CSM) |
[− −]^{b}
| 1 | E1 | Other | [78] |