Michael Kneiert, “Comparison of Wearable Camera Image Physical Activity Behavior Estimates to Direct Observation”
Mentor: Scott Strath, Kinesiology
Poster #72

PURPOSE: To assess the accuracy and precision of physical activity (PA) behavior estimates from wearable camera (WC) still-images (IMGs) to video-recorded direct observation (DO). METHODS: Participants (n=19) wore a WC above the xiphoid process while simultaneously being video recorded by researchers, during 3 visits. WC was set to the highest capture rate. A PA behavior annotation protocol was developed from the Compendium of Physical Activities. For analysis, PA behavior annotations were collapsed into 8 domains. A linear mixed effects model was used to calculate statistical bias and 95% CIs of IMGs to DO behavior times to determine accuracy and precision. Confusion matrices were computed to determine trends in behavior misclassification by IMGs against DO. One-way random effects interclass correlation coefficient (ICC) was calculated between domains to assess reliability. RESULTS: 53 visits were analyzed, total time of 4381.3 min (mean 82.7 ± 19.2 min). Discrepancies of PA behavior min estimation by IMGs against DO annotations were statistically insignificant at p > 0.05. Household had the smallest bias (0.09 ± 6.2 min) whereas, sport & exercise had the largest (1.61 ± 9.32 min). Confusion matrices determined IMG annotation scored “other” as “household” 26.3% of the time. ICC between IMGs and DO was excellent (ICC = 0.8945 [0.8938, 0.8953]). CONCLUSION: WC IMG annotation is accurate and precise when estimating PA behavior compared to annotated, DO videos. Future work examining WC use in more heterogeneous populations and over longer periods of time would further advance the application of this technology in measurement research.