Accuracy of the Fitbit Zip for Measuring Steps for Adolescents With Visual Impairments.

Our purpose in this study was to document the criterion validity of the Fitbit Zip for measuring steps taken by youth with visual impairments (VI). A secondary purpose was to determine whether walking pace, mounting position, or relative position to the user's mobility device impacted the criterion validity of the device. Fourteen adolescent-aged individuals (Mage = 15.4; 13 male and 1 female) with VI participated in this study. Participants wore four Fitbit Zips at different mounting positions and completed two, 2-min walking trials while the lead investigator hand tallied steps. Measurement validity was analyzed using absolute percent error (APE), intraclass correlation coefficients estimated level of conformity, and paired samples t tests and Cohen's d effect sizes assessed APE relative to mounting positions. Results supported the use of the Fitbit Zip during regular-paced walking; however, caution must be used during activities exceeding regular walking speeds, as devices consistently underestimated steps.