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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.