Table 3. Test-retest study: Intra class correlation coefficients between two estimations of total energy expenditure measured at two different times, 6 weeks apart, over one year period in the random sample of 121 young students from Bogotá, 2001-2002.

Categories	N	Intra-class correlation coefficient [95% CI]
All	121	.96 [.95 ; .97]
Age (years)
8-10	41	.94 [.89 ; .97]
11-13	40	.98 [.96 ; .99]
14-16	40	.95 [.91 ; .98]
Gender
Male	56	.98 [.96 ; .99]
Female	65	.95 [.91 ; .97]
School grade
Elementary School	41	.98 [.97 ; .99]
Secondary School	80	.94 [.91 ; .96]
Period activities
Vacation period	121	.97 [.96 ; .98]
School period	121	.96 [.94 ; .97]
Socio-economic strata (see map)
1-2	46	.94 [.90 ; .97]
3-4	40	.98 [.96 ; .99]
5-6	35	.99[.97 ; .99]
Activities
1- Sleeping	121	.93[.91 ; .95]
2- Toilet	121	.90[.87 ; .93]
3- Meals	121	.97[.96 ; .98]
4- Transportation	121	.84[.78 ; .89]
5- Classroom	121	.97[.96 ; .98]
6- Mandatory physical education	121	.95[.93 ; .97]
7- Other activities in school	121	.94[.92 ; .96]
8- Out school activities	121	.96[.94 ; 97]
9- Religious activities	121	.93[.90 ; .95]
10- Vacations	121	.97[.96 ; .98]
11- Personal artistic activities	121	.98[.97 ; .99]
12- Sport competition	121	.98[.97 ; .99]
13- Home activities	121	.89[.85 ; .92]