The lowest average systematic error in the walking tests was -0.2%, recorded on the Garmin Vivofit 2 at 3.5 km/h; the highest error was the Fitbit Charge HR at 2 km/h with an error margin of 26.8%. 
Garmin Vivofit 2
The lowest average systematic error in the walking tests was -0.2%, recorded on the Garmin Vivofit 2 at 3.5 km/h; the highest error was the Fitbit Charge HR at 2 km/h with an error margin of 26.8%.  Comparisons of pulse measurements from the Fitbit Charge HR revealed a margin error of -3.42% ± 7.99% compared to the electrocardiogram. 
Fitbit Charge HR
The Beddit sleep tracker measured a systematic error of -3.27% ± 4.60%.



Beddit