Psychometric properties of the Last-7-Day Sedentary Time Questionnaire (SIT-Q-7d): Testing the validity and reliability among general population

BACKGROUNDS: Sedentary behavior (SB) is an independent risk factor causing chronic diseases. Previous studies compared sitting time mostly with physical activity. The present study aimed to evaluate the validity and reliability of the Last-7-Day Sedentary Time Questionnaire (SIT-Q-7d) in Iran. Moreover, SB was assessed among the study participants. METHODS: The current validity study was conducted among 290 subjects (51.7% males vs. 48.3% females) with a mean age of 34.81 ± 9.63 years in Poldasht, Iran. Sampling was done using simple random sampling and the data were collected using the SIT-Q-7d. To confirm the validity of the questionnaire, forward–backward translation method, content validity, and construct validity were used. Furthermore, temporal stability was calculated by the test–retest method and internal consistency coefficient (ICC). RESULTS: Our results confirmed the content validity of the questionnaire (content validity score: 0.90 and content validity index: 0.80). Using exploratory factor analysis (EFA), seven factors of SB were identified as follows: eating while sitting down, doing domestic affairs, screen time, leisure time, studying books, watching TV, and attending family gatherings. The reliability of the questionnaire was confirmed using Cronbach’s alpha (α = 0.7). In addition, temporal stability was confirmed by test–retest method and ICC was 0.9 (95% CI: 83–97). CONCLUSION: Our results confirmed that the Persian version of SIT-Q-7d is a reliable and valid tool for assessing SB. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12889-022-14262-x.