Table 1.

Sample characteristics: national longitudinal study of adolescent to adult health, 1994–2008 (public use).

Total	Frequency Weighted percent
	5,077	100.0
1Smoking (Wave I)
No	3,817	73.7
1–5 cpd (light)	787	15.9
6–16 cpd (average)	320	6.8
17 or more cpd (heavy)	153	3.6
Smoking (Wave IV)
No	3,248	61.7
1–5 cpd (light)	736	14.4
6–16 cpd (average)	680	14.7
17 or more cpd (heavy)	413	9.3
Race/ethnicity
Non-Hispanic white	3,206	70.1
Non-Hispanic black	1,138	15.2
Hispanic	530	11.1
Other	203	3.6
Sex
Female	2,746	49.6
Male	2,330	50.4
Age group in Wave I
11–14 years	1,187	25.1
15–16 years	1,780	34.7
17 years and above	2,107	40.2
Dental visit (Wave I)
Within the year	3,430	68.3
Within 1–2 years	979	19.3
Over 2 years	540	10.2
Never	114	2.2
2Close friends who smoke (Wave I)
None	2,792	54.3
1 close friend smokes	1,006	20.5
2 close friends smoke	596	12.1
3 close friends smoke	609	13.1
Adequate sleep (Wave I)
Yes	3,705	74.1
No	1,365	25.9
Exercised during the past week (Wave I)
None	816	16.9
1–2 times	1,622	33.1
3–4 times	1,278	24.8
5 times or more	1,357	25.2
3Depression symptoms (Wave I)
Yes	770	14.8
No	4,307	85.2
Body mass index (Wave I)
0 to less than 25	3,866	76.5
25 to less than 30	780	15.6
30 and above	431	7.9

cpd: cigarettes per day.

¹Number of cigarettes smoked per day on the days in which the participant smoked during the previous month.

²Participants were asked if any of their three best friends smoked.

³A cut point score of 24 on epidemiologic studies depression scale.