. 2015 Nov 17;76(6):852–861. doi: 10.15288/jsad.2015.76.852

Table 5.

Prevalence of early substance involvement in European American twins from twin-reported low and higher parental monitoring families, by predicted parental monitoring quintile^a

	Predicted probability of low parental monitoring
	Lowest risk quintile (0-20th percentile)		Moderately low risk (21st–40th percentile)		Middle risk quintile (41st-60th percentile)		Moderately high risk (61st-80th percentile)		Highest risk quintile (81st-100th percentile)
Variable	Reported higher monitoring	Reported lower monitoring	Reported higher monitoring	Reported lower monitoring	Reported higher monitoring	Reported lower monitoring	Reported higher monitoring	Reported lower monitoring	Reported higher monitoring	Reported lower monitoring
Alcohol use ≤14
n in group	553	68	541	75	509	104	448	163	373	234
n early users (%)	76 (13.7)	24 (35.3)^*	100 (18.5)	25 (33.3)^*	108 (21.2)	38 (36.5)^*	81 (18.1)	67 (41.1)^*	118 (31.6) 120 (51.3)^*
Tobacco use ≤11
n in group	537	65	535	72	499	103	443	163	369	234
n early users (%)	20 (3.7)	7 (10.8)^*	43 (8.0)	10(13.9)	49 (9.8)	22 (21.4)^*	88 (19.9)	40 (24.5)	91 (24.7)	94 (40.2)^*
Cannabis use ≤14
n in group	553	68	541	75	509	104	448	163	373	234
n early users (%)	13 (2.4)	2 (2.9)	23 (4.3)	7 (9.3)	17 (3.3)	15 (14.4)^*	39 (8.7)	43 (26.4)^*	48(12.9)	78 (33.3)^*

^{^a}

All models also included birth cohort as a covariate.

Indicates that within propensity score quintile the lowest 25% and upper 75% twin-report-based parental monitoring groups differed significantly at p < .05.