This study examined the 1-yr test–retest reliability and criterion validity of sedentary time survey items in a subset of participants from a large, nationwide prospective cohort.
Participants included 423 women and 290 men age 31 to 72 yr in the Cancer Prevention Study-3. Reliability was assessed by computing Spearman correlation coefficients between responses from prestudy and poststudy surveys. Validity was assessed by comparing survey-estimated sedentary time with a latent variable representing true sedentary time estimated from the 7-d diaries, accelerometry, and surveys through the method of triads. Sensitivity analyses were restricted to 566 participants with an average of 14+ h of diary and accelerometer data per day for 7 d per quarter.
Reliability estimates for total sitting time were moderate or strong across all demographic strata (Spearman ρ ≥ 0.6), with significant differences by race (P = 0.01). Reliability estimates were strongest for the TV-related sedentary time item (Spearman ρ, 0.74; 95% confidence interval, 0.70–0.77). The overall validity coefficient (VC) for survey-assessed total sedentary time was 0.62 (95% confidence interval, 0.55–0.69), although VC varied by age group and activity level (P < 0.05). However, VC were similar across groups (P < 0.05) when restricting to highly compliant participants in a sensitivity analysis.
The Cancer Prevention Study-3 sedentary behavior questionnaire has acceptable reliability and validity for ranking or categorizing participants according to sedentary time. Acceptable reliability and validity estimates persist across various demographic subgroups.
1American Cancer Society, Atlanta, GA;
2Department of Kinesiology, University of Georgia, Athens, GA;
3Metabolic Epidemiology Branch, National Cancer Institute, Bethesda, MD;
4Department of Kinesiology, California Polytechnic State University, San Luis Obispo, CA; and
5Department of Health Promotion and Behavior, University of Georgia, Athens, GA
Address for correspondence: Erika Rees-Punia, Ph.D., M.P.H., American Cancer Society, 250 Williams St. NW, Atlanta, GA 30303; E-mail: Erika.Rees-Punia@cancer.org.
Submitted for publication February 2018.
Accepted for publication July 2018.