Table 1.

Characteristics of participants according to age group, sex, and sexual activity: mean (standard error).

	15 to 18 years old
	Boys		Girls
	Not active	Active	Not active	Active
Age (years)	16.33 (0.03)	17.01 (0.08)	16.25 (0.03)	16.87 (0.11)
N	4047	313	3888	598
Go to school (%)	43% (2%)	27% (5%)	47% (2%)	3% (1%)
N	3868	303	3732	567
Work (%)	55% (2%)	68% (5%)	34% (2%)	17% (2%)
N	3960	312	3830	596
Work and study (%)	12% (1%)	11% (3%)	10% (1%)	6% (3%)
N	3429	256	2783	130
Smokes (%)	12% (1%)	35% (4%)	3% (1%)	6% (2%)
N	2298	289	2785	576
Drinks alcohol (%)	19% (2%)	42% (4%)	9% (1%)	12% (2%)
N	2301	289	2789	578
Have tried marihuana (%)	2% (1%)	9% (4%)	0% (0%)	0% (0%)
N	2299	290	2787	579
Have participated in violent activities (%)	5% (1%)	7% (2%)	4% (1%)	3% (1%)
N	2292	289	2781	578
Receive support (%)	73% (2%)	72% (5%)	80% (1%)	72% (73%)
N	2295	290	2784	579
Have had sex (%)	8% (1%)		15% (1%)
N	4360		4486
	19 to 21 years old
	Boys		Girls
	Not active	Active	Not active	Active
Age (years)	19.94 (0.04)	20.03 (0.09)	19.93 (0.03)	19.99 (0.05)
N	1719	381	1611	887
Go to school (%)	13% (1%)	9% (2%)	16% (2%)	4% (1%)
N	1578	368	1508	834
Work (%)	80% (2%)	80% (4%)	46% (3%)	20% (2%)
N	1666	380	1577	886
Work and study (%)	4% (1%)	5% (2%)	10% (2%)	6% (3%)
N	1447	332	910	191
Smokes (%)	20% (20%)	35% (4%)	2% (1%)	3% (1%)
N	677	365	1056	860
Drinks alcohol (%)	34% (3%)	46% (5%)	11% (2%)	12% (2%)
N	681	366	1060	860
Have tried marihuana (%)	5% (2%)	3% (1%)	0% (0%)	0% (0%)
N	680	366	1059	860
Have participated in violent activities (%)	6% (2%)	8% (2%)	3% (1%)	5% (1%)
N	680	365	1062	865
Receive support (%)	75% (3%)	84% (3%)	82% (2%)	76% (2%)
N	678	366	1062	862
Have had sex (%)	18% (1%)		40% (2%)
N	2100		2498