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Table 2 Mean difference scores (gold standard – activity tracker) and MAPE in the laboratory and free-living condition

From: Reliability and validity of ten consumer activity trackers

Laboratory Condition 1 Free-living condition 2
  N Mean difference (SD) a MAPE b t-value/Z-value c P-value N Mean difference a MAPE b Z-value c P-Value
ActivPAL 25 9 (6) 0.3 7.19 0.000 * 55     
Lumoback 32 8 (20) 0.2 2.24 0.033 * 51 17 0.4 −0.97 0.332
Fitbit Flex 33 188 (219) 5.7 4.93 0.000 * 54 −150 3.7 −2.23 0.026 *
Jawbone UP 32 34 (123) 1.0 1.60 0.119 53 −58 1.4 −0.24 0.851
Nike+ Fuelband 33 598 (618) 18.0 −4.36 0.000 * 20 977 24 −3.55 0.000 *
Misfit Shine 33 −6 (43) 0.2 −0.80 0.430 55 −43 1.1 −0.36 0.719
Withings Pulse 32 15 (23) 0.5 3.70 0.001 * 51 323 7.9 −5.24 0.000 *
Fitbit Zip 32 11 (12) 0.3 5.44 0.000 * 55 −49 1.2 −2.66 0.008 *
Omron 32 −82 (157) 2.5 −2.96 0.006 * 55 17 0.4 −0.71 0.479
Digiwalker 32 38 (145) 1.2 1.46 0.153 55 240 5.9 −2.04 0.041 *
Moves app 33 −319 (366) 9.6 −4.36 0.000 * 11 1529 37.6 −2.85 0.004 *
  1. 1Mean (±SD) Optogait = 3314 (±162) 2 Mean (±SD) ActivPAL = 4070(±2430) *significant p-value indicating a systematic difference of the activity tracker. apositive values indicate an underestimation of the activity tracker and negative values indicate an overestimation. b MAPE = mean absolute percentage error cIn case of non-normality the Wilcoxon Signed Rank Test was used instead of the Paired Samples T-test