Table 2.

Relationship Between Marijuana Use Underreporting and Reported Use of Alcohol and Engaging in Sexual Risk Behavior at Each Time Point

	Baseline		3 mon. follow-up		6 mon. follow-up		12 mon. follow-up		18 mon. follow-up
Variable	MJ Underrep.	Others	MJ Underrep.	Others	MJ Underrep.	Others	MJ Underrep.	Others	MJ Underrep.	Others
a. Alcohol use:
None	100.0%	37.8%	90.0%	69.3%	100.0%	72.1%	100.0%	67.2%	90.9%	59.7%
Use 1 or more times	-	62.2%	10.0%	30.7%	-	27.9%	-	32.8%	9.1%	40.3%
	100.0%	100.0%	100.0%	100.0%	100.0%	100.0%	100.0%	100.0%	100.0%	100.0%
One-sided Fisher’s Exact
Test p-level	p = .056		p = .037		p = .002		p = .010		p = .035
b. Sexual risk behavior:
None	66.7%	55.6%	50.0%	54.0%	61.9%	50.0%	58.3%	46.9%	72.7%	40.3%
Engaged one or more	33.3%	44.4%	50.0%	46.0%	38.1%	50.0%	41.7%	53.1%	27.3%	59.7%
	100.0%	100.0%	100.0%	100.0%	100.0%	100.0%	99.97%	100.0%	100.0%	100.0%
One-sided Fisher’s Exact
Test p-level	p = n.s.		p = n.s.		p = n.s.		p = n.s.		p = .037
n	3	293 or 294	20	226 or 228	21	214 or 215	12	194 or 195	11	154

Note. MJ underrep. refers to youth who were identified as possibly underreporting their marijuana use.