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Table 1 Potential correlates of objectively measured sedentary time and self-reported sedentary behaviour

From: Correlates of objectively measured sedentary time and self-reported screen time in Canadian children

Variable Measurement method Use in analysis
Anthropometric
Sex Parent-report: Demographic and Family History Questionnaire Binary variable: male, female (used as a covariate)
BMI Directly measured height and weight, calculated using CDC cut-points [23] Ordered categorical: underweight, normal weight, overweight, obese
Percent body fat Directly measured using Tanita Continuous
Waist circumference Directly measured by ISCOLE researcher Continuous
Child ethnicity Parent-report: Demographic and Family History Questionnaire Categorical: white, African American, Asian, First Nations, East Indian, don’t know, other (used as a covariate)
Behavioural characteristics
Healthy and unhealthy eating scores Child-report food frequency questionnaire: ISCOLE Diet and Lifestyle Questionnaire Continuous: Continuous: obtained from a principal component analysis derived from a 23-item food frequency questionnaire
Breakfast consumption (weekend, and weekday) Child-report: ISCOLE Diet and Lifestyle Questionnaire Re-coded as dichotomous: those who ate breakfast at least once per weekday (versus never) and those who at breakfast at least weekend day (versus never).
Commute to school (main part of journey) Child-report: ISCOLE Diet and Lifestyle Questionnaire Re-coded as dichotomous: active (walking, bicycle/rollerblade/skateboard/scooter, other), and inactive (bus/train/tram/underground/boat, car/motorcycle/moped)
Sleep (in the past week) Child-report: ISCOLE Diet and Lifestyle Questionnaire Categorical: Sleep quality (4 responses: very good, fairly good, fairly bad, very bad), sleep quantity (4 responses: very good, fairly good, fairly bad, very bad). Re-coded for analysis, collapsing very good and fairly good categories, and fairly bad and very bad categories for both sleep quality and sleep quantity.
Physical activity Child-report: ISCOLE Diet and Lifestyle Questionnaire Categorical: 8 responses (0 days, 1 day, 2 days, 3 days, 4 days, 5 days, 6 days, 7 days). Was included in the model re-coded as those active more and less than 6 days in the past week.
Accelerometer measured minutes per day of LPA and MVPA Accelerometer: time spent at different PA intensities using Evensen cut-points [19]
Family situation
Number of siblings Parent-report: Demographic and Family History Questionnaire Continuous (used as a covariate)
Parental BMI Parent-report: Demographic and Family History Questionnaire Re-coded as dichotomous: normal weight, or overweight/obese
Parental education Parent-report: Demographic and Family History Questionnaire Re-coded as dichotomous: ≤high school, and high school or higher
Combined household income Parent-report: Demographic and Family History Questionnaire Ordered categorical: 8 options ranging from < $14,999, to > $140,000 or more (used as covariate). In the model, income was re-coded as above/below mean category.
Home environment
Number of TVs in home Parent report: ISCOLE neighbourhood and home environment questionnaire Re-coded as dichotomous: ≤1, and ≥2
TV/electronics in bedroom Child-report: ISCOLE Diet and Lifestyle Questionnaire Binary response: yes/no
Parent report: ISCOLE neighbourhood and home environment questionnaire
Automobile ownership Parent report: ISCOLE neighbourhood and home environment questionnaire Continous: number of working automobiles owned per household. Re-coded as dichotomous: <2 and ≥2.
  1. BMI: body mass index; ISCOLE: International Study of Childhood Obesity Lifestyle and the Environment; LPA: light-intensity physical activity; MVPA: moderate- to-vigorous-intensity physical activity; PA: physical activity.