Measuring Total and Domain-Specific Sitting: A Study of Reliability and Validity

MARSHALL, A. L., Y. D. MILLER, N. W. BURTON, and W. J. BROWN. Measuring Total and Domain-Specific Sitting: A Study of Reliability and Validity. Med. Sci. Sports Exerc., Vol. 42, No. 6, pp. 1094-1102, 2010. Purpose: Although independent relationships between sitting behaviors (mainly television viewing) and health outcomes have been reported, few studies have examined the measurement properties of self-report sitting questions. This study assessed gender-specific test-retest reliability and validity of a questionnaire that assessed time spent sitting on weekdays and weekend days: 1) traveling to and from places, 2) at work, 3) watching television, 4) using a computer at home, and 5) for leisure, not including television. Methods: Test-retest reliability of domain-specific sitting time (min.d(-1)) on weekdays and weekend days was assessed using data collected on two occasions (median = 11 d apart). Validity of domain-specific self-reported sitting time on weekdays and weekend days was assessed against log data and sedentary accelerometer data. Results: Complete repeat questionnaire and log data were obtained from 157 women (aged 51-59 yr) and 96 men (aged 45-63 yr). Reliability coefficients were high for weekday sitting time at work, watching television, and using a computer at home (r = 0.84-0.78) but lower for weekend days across all domains (r = 0.23-0.74). Validity coefficients were highest for weekday sitting time at work and using a computer at home (r = 0.69-0.74). With the exception of computer use and watching television for women, validity of the weekend-day sitting time items was low. Conclusions: This study confirms the importance of measuring domain-and day-specific sitting time. The measurement properties of questions that assess structured domain-specific and weekday sitting time were acceptable and may be used in future studies that aim to elucidate associations between domain-specific sitting and health outcomes.