Table 3.

Teen and Sibling Descriptive Statistics for Study Variables at Baseline and 3, 6, and 12 month Follow-up

Assessment:	Baseline		3 month follow-up		6 month follow-up		1 year follow-up
Alcohol Use Frequency
Teen	N	(%)	N	(%)	N	(%)	N	(%)
Every Day	0	(0%)	0	(0.0%)	1	(1.1%)	0	(0.0%)
4–6 days/week	2	(1.8%)	1	(1.1%)	1	(1.1%)	0	(0.0%)
2–3 days/week	8	(7.3%)	6	(6.7%)	9	(10.1%)	10	(11.8%)
Once per week	12	(11.0%)	11	(12.4%)	9	(10.1%)	4	(4.7%)
Less than once per week	21	(19.3%)	12	(13.5%)	19	(21.3%)	19	(22.4%)
Once per month	13	(11.9%)	11	(12.4%)	4	(4.5%)	13	(15.3%)
Less than Once per month	30	(27.5%)	22	(24.7%)	17	(19.1%)	10	(11.8%)
none	23	(21.1%)	26	(29.2%)	29	(32.6%)	29	(34.1%)
Sibling
Every Day	0	(0.0%)	0	(0.0%)	0	(0.0%)	0	(0.0%)
4–6 days/week	1	(1.0%)	0	(0.0%)	1	(1.2%)	0	(0.0%)
2–3 days/week	3	(3.0%)	5	(6.1%)	7	(8.6%)	7	(9.2%)
Once per week	9	(9.1%)	4	(4.9%)	7	(8.6%)	4	(5.3%)
Less than once per week	14	(14.1%)	10	(12.2%)	9	(11.1%)	10	(13.2%)
Once per month	8	(8.1%)	5	(6.1%)	4	(4.9%)	5	(6.6%)
Less than Once per month	12	(12.1%)	7	(8.5%)	13	(16.0%)	7	(9.2%)
none	52	(52.5%)	51	(62.2%)	40	(49.4%)	43	(56.6%)
Marijuana Use (yes)
Teen	69	(67.7%)	56	(62.9%)	59	(66.3%)	51	(60.0%)
Sibling	39	(42.4%)	32	(39.0%)	32	(39.5%)	31	(40.8%)
Parental Monitoring	M	(SD)	M	(SD)	M	(SD)	M	(SD)
Teen	3.37	(.83)	3.60	(.81)	3.26	(.90)	3.15	(1.00)
Sibling	3.76	(1.02)	3.86	(0.91)	3.71	(.91)	3.54	(1.05)

Note. N’s vary with missing data. All substance use was assessed ‘over the past 3 months’. Parental monitoring was assessed using the Parent Monitoring Knowledge subscale of the Parental Monitoring Questionnaire