Measuring Time in the Office Using Bluetooth Sensors: Feasibility and Validity Considerations

• Published in: Journal for the measurement of physical behaviour 2019-03, Vol.2 (1), p.36-44
• Main Authors: Clark, Bronwyn K., Hadgraft, Nyssa T., Sugiyama, Takemi, Winkler, Elisabeth A.
• Format: Article
• Language: English
• Subjects: Accuracy; Control charts; Movement; Offices; Wearable computers
• ISSN: 2575-6605; 2575-6613
• DOI: 10.1123/jmpb.2018-0046

The office is a key setting for intervening to reduce sitting, therefore office-specific activity measures are needed to evaluate interventions. We tested whether valid measures of office time and office-specific activities could be obtained using Bluetooth sensing with a variety of sampling intervals, receiver wear positions, and beacon placements. Workers from one building (n = 29, 72% female, age 23–68 years) wore, for one workday, the activPAL3 on the thigh (measured sitting, standing and stepping) and the Bluetooth-enabled ActiGraph Link on the wrist and thigh. Location (office/not) was estimated by Bluetooth signal presence/absence at two beacons in the wearer’s office (desk, wall), with chest-worn video cameras as the criterion. Accuracy in location classification was assessed and compared across 60-s, 30-s, and 10-s sampling intervals. The validity of Bluetooth-derived measures of total time in the office and in office-specific activities was assessed. For both the wrist and thigh-worn Link, with various beacon placements, accurate classification of location (office/not) was obtained, with a significant (p