Fig. 1

Mean absolute percentage error (MAPE) of each wearable technology across walking speeds. Participants walked on a treadmill for 5-min bouts beginning at 0.8 km/h (0.5 mph) and increasing in 0.8 km/h (0.5 mph). MAPE (%) was computed for each person bout subtracting the directly observed steps (criterion measurement) from the wearable technology-derived steps and dividing it in absolute value by the directly observed steps. Black dots represent the averaged MAPE across all sample for a given speed. Bars represent standard deviation of MAPE. The standard deviation bars were not drawn when they were shorter than the height of the symbol. Lower MAPE values indicate higher accuracy of the wearable technology of interest. See Additional file 2 for a graphical classification of wearable technologies by age groups