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. 2018 Jul 6;8(7):e019639. doi: 10.1136/bmjopen-2017-019639

Table 1.

Study sample characteristics

Variable Complete data
(n=415 666)
Incomplete data
(n=86 877)
P values* d
Mean age, years (SD) 56.64 (8.14) 56.01 (7.85) <0.0001 0.08
Sex, n (%) <0.0001 0.02
 Female 225 456 (54.2%) 47 979 (55.2%)
 Male 190 210 (45.8%) 38 898 (44.8%)
Race, n (%) <0.0001 0.15
 Mixed/Other 5284 (1.3%) 2233 (2.6%)
 Asian 8267 (2.0%) 3184 (3.7%)
 Black 5439 (1.3%) 2618 (3.0%)
 White 395 506 (95.2%) 77 235 (88.9%)
 Do not know/Prefer not to answer 1170 (0.3%) 1607 (1.9%)
Education, n (%) <0.0001 0.19
 College 144 599 (34.8%) 16 585 (19.1%)
 No college 268 275 (64.5%) 62 947 (72.5%)
 Prefer not to answer 2792 (0.7%) 2699 (3.1%)
 Missing 0 (0.00%) 4646 (5.4%)
Employment status, n (%) <0.0001 0.26
 Employed 256 588 (61.7%) 30 593 (35.2%)
 Unemployed 12 079 (2.9%) 1780 (2.1%)
 Retired 146 999 (35.4%) 19 998 (23.0%)
 None of the above/Prefer not to answer 0 (0.00%) 4886 (5.6%)
 Missing 0 (0.00%) 29 620 (34.1%)
Shift work, n (%) <0.0001 0.14
 Yes 42 285 (10.2%) 7266 (8.4%)
 No 372 902 (89.7%) 44 865 (51.6%)
 Do not know/Prefer not to answer 479 (0.1%) 240 (0.3%)
 Missing 0 (0.00%) 34 506 (39.7%)
Residence, n (%) <0.0001 0.13
 Urban 355 222 (85.5%) 73 587 (84.7%)
 Rural 60 429 (14.5%) 8232 (9.5%)
 No postal code provided 15 (0.00%) 3 (0.00%)
 Missing 0 (0.00%) 5055 (5.8%)
Season of assessment, n (%) <0.0001 0.04
 Fall (September–November) 100 142 (24.1%) 19 257 (22.2%)
 Winter (December–February) 86 848 (20.9%) 17 815 (20.5%)
 Spring (March–May) 119 536 (28.8%) 26 949 (31.0%)
 Summer (June–August) 109 140 (26.3%) 22 853 (26.3%)
 Missing 0 (0.00%) 3 (0.00%)
Mean TV Use, hours/day (SD) 2.69 (1.6) 3.35 (2.1) <0.0001 0.40
Mean computer use, hours/day (SD) 1.08 (1.4) 1.10 (1.5) 0.0009 0.01
Mean driving time, hours/day (SD) 0.99 (1.2) 0.89 (1.3) <0.0001 0.08
Mean overall sedentary behaviour, hours/day (SD) 4.76 (2.3) 4.98 (2.8) <0.0001 0.09
Mean total physical activity, excess MET-hours/week (SD) 31.78 (33.0) 27.65 (32.0) <0.0001 0.13
Categorised total physical activity, n (%) <0.0001 0.18
 Low activity (<10 excess MET-hours/week) 109 215 (26.3%) 13 809 (15.9%)
 Moderate activity (10–49.9 excess MET-hours/week) 223 597 (53.8%) 19 142 (22.0%)
 High activity (≥50 excess MET-hours/week) 82 854 (19.9%) 6436 (7.4%)
 Missing 0 (0.00%) 47 490 (54.7%)

Column percentages do not always add up to 100% because of rounding.

*P values based on χ² tests for categorical variables and two-sample t-tests for continuous variables.

d, Cohen’s d effect size; MET, metabolic equivalents; n, frequency.