Phases of Accuracy Diagnosis: (In)visibility of System Status in the Fitbit


  • Molly Zellweger Mackinlay Stanford University


Fitbit, Activity trackers, system status, maxim of quality


This paper analyzes the Fitbit – an all-in-one step, floor, distance, calorie, and sleep tracker – in order to discover how users approach and deal with the question of accuracy in black-box systems. Due to learned expectations of system unreliability, users are skeptical of the authenticity of Fitbit-recorded data. However, due to the limited visibility of system status their efforts to test and calibrate their data are ultimately flawed. Users move through four main phases in which they perform a number of tests to diagnose and understand the Fitbit's level of precision, while revising their mental model of the Fitbit itself and attempting to calibrate their personal use of the device. This paper examines the results of seven interviews with Fitbit users, hypothesizes and describes four phases of use many Fitbit users undergo, and critiques the usability problems that these interviews unearthed.

Author Biography

  • Molly Zellweger Mackinlay, Stanford University
    Molly is a CoTerm student in the Department of Computer Science persuing her masters in Human Computer Interaction.






Research Articles