This study provides a new test of time-use diary methodology, comparing diaries with a pair of
objective criterion measures: wearable cameras and accelerometers.
A volunteer sample of respondents (n=148) completed conventional self-report paper time-use
diaries using the standard UK Harmonised European Time Use Study (HETUS) instrument (Eurostat 2009). On the diary day, respondents wore a camera that continuously recorded images of their activities during waking hours (approx. 1500-2000 images/day) and also an accelerometer that recorded their physical activity (PA) continuously throughout the 24-hour period covered by the diary. Of the initial 148 participants recruited, 131 returned usable diary and camera records, of whom 124 also provided a usable whole-day accelerometer record.
The comparison of the diary data with the camera and accelerometer records strongly supports
using diary methodology at both the aggregate (sample) and individual levels and provides evidence that time-use data may be a preferable alternative to PA Questionnaires (PAQs) for providing population-level estimates of physical activity energy expenditure (PAEE). It implies new
opportunities for calibrating metabolic equivalent of task (MET) attributions to activities, using large scale time-use diary studies deployed for samples representative of national populations.