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Table 3 Validity indices (accuracy, bias, and precision) averaged across all wearable technologies and presented by age group

From: A catalog of validity indices for step counting wearable technologies during treadmill walking: the CADENCE-Kids study

  Treadmill speed, km/h (mph)   
Slow Normal Fast
0.8 (0.5) 1.6 (1.0) 2.4 (1.5) 3.2 (2.0) 4.0 (2.5) 4.8 (3.0) 5.6 (3.5) 6.4 (4.0) 7.2 (4.5) 8.0 (5.0)
Children (612 years)
MAPE ± SD 76.7 ± 30.0 58.2 ± 36.2 38.0 ± 32.6 24.1 ± 30.1 17.3 ± 29.3 16.0 ± 28.3 16.3 ± 28.9 18.5 ± 28.1 24.1 ± 30.2
MPE ± SD −76.7 ± 30.0 − 57.6 ± 37.1 −37.6 ± 33.1 −22.8 ± 31.0 − 16.7 ± 29.6 − 14.3 ± 29.2 −15.3 ± 29.4 −17.5 ± 28.8 −22.4 ± 31.5
Adolescents (1317 years)
MAPE ± SD 81.2 ± 30.0 61.7 ± 37.7 39.4 ± 33.6 23.6 ± 29.9 17.0 ± 30.0 14.9 ± 29.1 14.6 ± 28.7 16.0 ± 28.8 18.6 ± 29.3 16.5 ± 25.1
MPE ± SD −80.9 ± 31.2 − 60.8 ± 39.1 −38.2 ± 35.0 −22.3 ± 30.9 −16.0 ± 30.5 −14.0 ± 29.6 −13.5 ± 29.2 −15.1 ± 29.3 −17.6 ± 29.9 −15.4 ± 25.8
Young adults (1820 years)
MAPE ± SD 80.6 ± 31.9 60.6 ± 38.7 36.9 ± 35.5 21.0 ± 28.8 15.8 ± 29.4 14.9 ± 29.5 14.4 ± 28.7 14.9 ± 28.4 16.2 ± 28.9 20.4 ± 28.4
MPE ± SD − 80.6 ± 32.1 − 59.7 ± 40.0 −35.4 ± 37.1 −19.6 ± 29.8 −14.8 ± 29.9 −14.8 ± 29.9 −13.8 ± 29.1 −13.9 ± 28.9 −15.3 ± 29.4 −16.6 ± 30.9
  1. All mean absolute percentage error (MAPE) and mean percentage error (MPE) values are presented as mean percentage ± standard deviation (SD). MAPE and MPE values were calculated for all wearable technologies (Actical, ActiGraph GT3X+ [waist], ActiGraph GT3X+ [non-dominant wrist], activPAL, Digi-Walker SW-200, NL-1000, SenseWear, and StepWatch) when compared to the directly observed steps. MAPE and SD values closer to 0% indicate higher accuracy and precision, respectively. MPE values closer to 0% indicate lower bias and negative values mean undercounting