Fig. 4

Effect of speed on overall accuracy (mean absolute percentage error, MAPE) of wearable technology’s step counting ability. MAPE and corresponding 95% confidence intervals (CIs) respective to each technology are plotted across speed bouts. Slow speed bouts: 0.8, 1.6, 2.4, 3.2 km/h (0.5, 1.0, 1.5, 2.0 mph); normal speed bouts: 4.0, 4.8, 5.6, 6.4 km/h (2.5, 3.0, 3.5, 4.0 mph); fast speed bouts: 7.2, 8.0 km/h (4.5, 5.0 mph). Each black dot represents grouped averages of MAPE values, with 95% CIs estimated using mixed effect models and extending above and below that point estimate. The 95% CIs bars were not drawn when they were shorter than the height of the symbol. MAPE values closer to 0 (indicated by a dashed line) are indicative of greater accuracy. 95% CIs bars that do not overlap are interpreted as significantly different among them. Likelihood ratio test P value is reported for the effect of all speeds on MAPE for each specific device. See Additional file 2 for a graphical classification of wearable technologies’ location by age groups