. Author manuscript; available in PMC: 2010 Dec 22.

Published in final edited form as: Subst Use Misuse. 2009;44(5):722–739. doi: 10.1080/10826080802490097

Table 2.

Covariates and their relationship with outcomes

Covariate^a	Total sample mean (SD)	Ever used marijuana mean (SD)		P value^b	Ever used alcohol mean (SD)		P value^c
Covariate^a	Total sample mean (SD)	Yes	No	P value^b	Yes	No	P value^c
Demanding parenting (1–4)	3.3 (0.6)	3.1 (0.6)	3.4 (0.6)	<0.001	3.2 (0.6)	3.4 (0.5)	<0.001
My parents have rules I have to follow
My parents always want to know where I am
Responsive parenting (1–4)	3.3 (0.6)	3.1 (0.6)	3.3 (0.6)	<0.001	3.2 (0.6)	3.3 (0.6)	<0.001
My parents listen to what I have to say
My parents care about me
Stress (1–4)	2.7 (0.9)	2.6 (0.9)	2.7 (0.9)	<0.001	2.8 (0.8)	2.6 (0.9)	0.01
I have a lot of stress in my life
Sensation seeking (1–4)	2.7 (0.7)	3.0 (0.5)	2.6 (0.7)	<0.001	2.9 (0.6)	2.4 (0.7)	<0.001
I like to do dangerous things
I like to listen to loud music
Rebelliousness (1–4)	1.9 (0.6)	2.2 (0.6)	1.7 (0.5)	<0.001	2.0 (0.6)	1.6 (0.5)	<0.001
I get in trouble at school
I do whatever my teacher says to do^d
Depression (1–4)	1.7 (0.7)	1.8 (0.7)	1.6 (0.7)	<0.001	1.7 (0.7)	1.6 (0.6)	<0.001
Over the past 2 weeks, how often have you been bothered by these things?^e
(a) Little interest or pleasure in doing things
(b) Feeling down, depressed, or hopeless
Self-esteem (1–4)	3.1 (0.6)	3.1 (0.6)	3.1 (0.6)	0.64	3.1 (0.6)	3.2 (0.6)	0.05
I like myself the way I am
I worry that other kids do not like me^d
School Achievement (1–4)	3.3 (0.7)	3.0 (0.6)	3.4 (0.6)	<0.001	3.2 (0.7)	3.5 (0.6)	<0.001
I generally get good grades

Note: SD = standard deviation.

Unless otherwise noted, items used to measure these characteristics used a four-level Likert scale with responses ranging from strongly agree to strongly disagree. Higher values correspond to more of each characteristic.

These p-values were computed with t-tests comparing characteristics in ever users of marijuana with never users of marijuana.

These p-values were computed with t-tests comparing characteristics in ever users of alcohol with never users of alcohol.

These items were reverse coded.

Depression items were measured on a four-level Likert scale with response choices of “not at all,” “several days,” “more than half the days,” and “nearly every day.”