Variability and reliability study of overall physical activity and activity intensity levels using 24 h-accelerometry-assessed data

Table 2 PA within- and between-person variance and number of days to assess habitual PA, total (N = 50)

			Percent of total variance
PA parameter^a	Within-person variance	Between-person variance	Within-person variance	Between-person variance	Number of days
	s_w²	s_b²	s_w²	s_b²	D^b
Overall PA, cpm	0.09593	0.06317	60.3	39.7	7
Time in inactivity, min/d	0.00273	0.00225	54.9	45.1	6
Time in low intensity activity, min/d	0.06727	0.05627	54.5	45.5	6
Time in moderate activity, min/d	0.09604	0.05033	65.6	34.4	9
Time in vigorous activity, min/d	0.28890	0.21890	56.9	43.1	6
Time in very vigorous activity, min/d	0.57190	0.34590	62.3	37.7	8

cpm counts per minute, D number of days to assess physical activity based on a given r (assumed correlation between observed and true mean of physical activity parameter) [19], PA physical activity, s_b² between-person variance over 11 days of physical activity, s_w² within-person variance over 11 days of physical activity
^aall analyses were performed using log-transformed data
^bD is calculated based on an assumed correlation between observed and true mean physical activity of r = 0.9 and is rounded up to the nearest full number of days

ISSN: 1471-2458