Accelerometer data reduction in adolescents: effects on sample retention and bias

Table 5 Non-wear time (daily minutes) and sedentary time (% of total time accepted, daily minutes) in the different non-wear criteria for weight status and age groups, n = 1087 (Initial N = 1296)

	Non-wear time								Sedentary time
	Weight status				Age group				Weight status			Age group
	Under-/normal weight	Over-weight	Diff (%)	p-value	11-12 years	13-14 years	Diff (%)	p-value	Under-/normal weight	Over-weight	p-value	11-12 years	13-14 years	p-value
90 min non-wear	15	16	1 (6.7)	0.551	14	17	3 (21.4)	0.131	59% (484 of 812)	62% (503 of 815)	0.001	59% (481 of 811)	62% (502 of 816)	<0.001
60 min non-wear	18	20	2 (11.1)	0.527	18	21	3 (16.7)	0.115	59% (478 of 809)	61% (497 of 812)	0.002	59% (475 of 808)	61% (497 of 812)	<0.001
30 min non-wear	27	29	2 (7.4)	0.364	26	31	5 (19.2)	0.010	58% (469 of 801)	61% (486 of 804)	0.005	58% (466 of 800)	61% (486 of 803)	<0.001
20 min non-wear	35	40	5 (14.3)	0.049	34	40	6 (17.6)	<0.001	58% (462 of 795)	60% (476 of 795)	0.006	58% (459 of 794)	60% (477 of 794)	<0.001
10 min non-wear	55	65	10 (18.2)	<0.001	54	64	10 (18.5)	<0.001	57% (442 of 778)	59% (451 of 773)	0.016	57% (439 of 778)	59% (453 of 774)	<0.001
	Overall significant interaction (p < 0.01)				Overall significant interaction (p < 0.01)				Overall non-significant interaction (p > 0.05)			Overall non-significant interaction (p > 0.05)

Daytime activity included (defined as the period from 6 am to 10 pm). Sedentary time analyses: Proportion of sedentary time out of total time accepted in each of the non-wear settings. Number of valid days and daily wear time were fixed to at least 5 days of 10 hours. Results are based on a multilevel mixed effect linear regression model with interaction terms.

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