title: Can we use digital life-log images to investigate active and sedentary travel behaviour? Results from a pilot study.
abstract: BACKGROUND
  Active travel such as walking and cycling has potential to increase physical activity levels in sedentary individuals. Motorised car travel is a sedentary behaviour that contributes to carbon emissions. There have been recent calls for technology that will improve our ability to measure these travel behaviours, and in particular evaluate modes and volumes of active versus sedentary travel. The purpose of this pilot study is to investigate the potential efficacy of a new electronic measurement device, a wearable digital camera called SenseCam, in travel research.
  
  
  METHODS
  Participants (n = 20) were required to wear the SenseCam device for one full day of travel. The device automatically records approximately 3,600 time-stamped, first-person point-of-view images per day, without any action required by the wearer. Participants also completed a self-report travel diary over the same period for comparison, and were interviewed afterwards to assess user burden and experience.
  
  
  RESULTS
  There were a total of 105 confirmed journeys in this pilot. The new SenseCam device recorded more journeys than the travel diary (99 vs. 94). Although the two measures demonstrated an acceptable correlation for journey duration (r = 0.92, p < 0.001) self-reported journey duration was over-reported (mean difference 154 s per journey; 95% CI = 89 to 218 s; 95% limits of agreement = 154 ± 598 s (-444 to 752 s)). The device also provided visual data that was used for directed interviews about sources of error.
  
  
  CONCLUSIONS
  Direct observation of travel behaviour from time-stamped images shows considerable potential in the field of travel research. Journey duration derived from direct observation of travel behaviour from time-stamped images appears to suggest over-reporting of self-reported journey duration.
authors: British Heart Foundation Health Promotion Research Group, University of Oxford, UK. paul.kelly@dph.ox.ac.uk
authors: Paul
authors: P
authors: Kelly
authors: Aiden
authors: A
authors: Doherty
authors: Emma
authors: E
authors: Berry
authors: Steve
authors: S
authors: Hodges
authors: Alan M
authors: AM
authors: Batterham
authors: Charlie
authors: C
authors: Foster
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