Table 1.

Means and p-Values Comparing Driver History Data for Telephone Survey Respondents, Refusals, and Non-Contacts ^a

Variables in Response Model	Respondents (n = 1528)	Refusals (n = 528)	Non- Contacts (n = 1383)	p-value
Age in years	17.10	17.14	16.97	0.0004
Proportion male	0.47	0.60	0.53	<.0001
Proportion living with single parent	0.20	0.21	0.27	<.0001
Proportion living with step/other parent	0.16	0.15	0.22	<.0001
Alcohol use/misuseb	2.75	2.80	2.83	0.3423
Alcohol availabilityc	3.38	3.37	3.33	0.5293
Intent to drink/next two yearsd	2.75	2.71	2.71	0.2535
Intent to drink/age 21d	2.83	2.79	2.77	0.1247
Cigarette usee	1.40	1.29	1.60	0.0003
Marijuana usee	0.58	0.61	0.78	0.0004
School gradesf	8.28	8.15	8.00	<.0001
Proportion with serious crash	0.28	0.31	0.31	0.6197
Proportion with serious offense	0.41	0.48	0.48	0.0074
Proportion with offense prior to licensure	0.02	0.05	0.06	<.0001

^aFor 3,439 of the 4,230 study subjects, 12^th grade questionnaire data were available.

^bScale: 1 = no alcohol use, to 4 = alcohol misuse two or more times.

^cScale: 1 = very hard to get, to 4 = very easy to get.

^dScale: 1 = definitely not, to 4 = definitely will.

^eScale: 0 = no use, to 5 = use every day.

^fScale: 1 = mostly F's, to 9 = mostly A's.