Table 1.

Comparison of randomized sample to denominators of interest on preliminary screening data.

Variable	Randomized (n=764)		All others consented (n=725)		All others recruited (n=2,850)		All others eligible (n=4,793)
	Mean/percent	SD	Mean/percent	SD	Mean/percent	SD	Mean/percent	SD
Age	35.12	10.31	32.59***	10.18	33.59***	10.53	33.98**	10.54
Gender (% female)	60.5		57.9		50.0***		57.7
Education (highest grade completed)
Grade 1–8	0.3		0.2		0.4		0.5
Grade 9–11	2.4		3.6		3.4		3.3
Grade 12 or GED	19.8		19.6		21.6		21.4
College 1–3 years	48.4		46.1		44.1		44.7
College 4 years or more	29.2		30.5		30.5		30.1
Race
White	86.4		85.5		85.2**		91.0***
Black	7.5		6.6		5.6		3.4
Asian	3.7		4.7		6.0		3.7
Native Hawaiian/Other Pacific Islander	0.5		1.8		1.6		1.0
American Indian/Alaska Native	2.0		1.4		1.6		0.9
Time of recruitment
Early morning (6 A.M.–9 a.m.)	11.4%		9.0%		9.5%		9.5%
Work hours (9 a.m.–5 p.m.)	60.2%		58.9%		59.6%		58.9%
Early evening (5 p.m.–9 p.m.)	16.4%		17.9%		18.8%		18.8%
Overnight (9 p.m.–6 a.m.)	12.0%		14.2%		12.0%		12.8%
Daily smoking rate	21.10	10.09	20.30	9.86	19.76***	9.56	20.00**	9.48
Time to first cigarette
Within 5 min	38.1		37.5		35.1***		35.3**
6–30 min	39.8		36.0		36.8		36.8
31–60 min	14.8		15.6		15.9		16.5
After 60 min	7.3		10.9		12.1		11.4
No. quit attempts past year	2.88	5.94	2.16**	4.69	2.42	6.18	2.39*	5.97
Age at first puff	14.48	3.51	14.80	3.57	14.96***	3.71	14.87**	3.69

Note. Comparison group for all t-test and chi-squared analyses is randomized (n=764). All others consented=1,489 minus 764=725. All others recruited=3,614 minus 764=2,850. All others eligible=5,557 minus 764=4,793.

^*p<.05;

^**p<.01;

^***p<.001.