Background: Does asking for the percentage of time spent sitting during work (P-method) instead of asking for the absolute length of time spent sitting (T-method) improve properties of the workers’ sitting- and walking-time questionnaire (WSWQ)? The purpose of this study was to investigate whether questioning technique influences test-retest reliability and criterion validity of the WSWQ.
Methods: Sixty-five Japanese workers completed each version of the WSWQ in random order. Both questionnaires assessed quantities of time spent sitting or walking (including standing) during work time, non-working time on a workday, and anytime on a non-workday. Participants wore the thigh-worn inclinometer (activPAL) as criterion measure. Intraclass correlation coefficients (ICC) and Spearman’s ρ were used for the analyses.
Results: For all three domains, values of reliability and validity with the P-method tended to be higher than with the T-method: ICC values ranged from 0.48–0.85 for the T-method and from 0.71–0.85 for the P-method; Spearman’s ρ values ranged from 0.25–0.58 for the T-method and from 0.42–0.65 for the P-method. The validities with both methods on a workday (0.51–0.58 for the T-method and 0.56–0.65 for the P-method) were higher than validities on a non-workday (0.25–0.45 for the T-method and 0.42–0.60 for the P-method). In post-survey interviews, 48 participants (77%) chose the P-method as their preferred questioning style.
Conclusions: The study revealed that the P-method WSWQ had better reliability, validity, and ease of answering than the T-method, suggesting that the P-method can improve properties of the WSWQ and consequently advance the quality of epidemiological surveys in this field.
2016 Tomoaki Matsuo et al. This is an open access article distributed under the terms of Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.