Table 1.

Sample characteristics

Age group	n	Age pre M ± s (years)	Sex (% female)	Socioeconomic status
				Low (%)	Mid (%)	High (%)
6 to 10 years	647	8.3 ± 1.4	46.7	14.3	57.5	28.3
11 to 17 years	747	14.4 ± 2.0	53.9	18.6	59.7	21.7
All participants	1394	11.6 ± 3.5	50.5	16.6	58.6	24.8

M mean, s standard deviation