Table 2. Exposure to Marijuana Advertisements and Its Association With Marijuana Use Among US Middle and High School Students, Monitoring the Future Survey, 2014 and 2015^a .

Type of Advertisement	Unweighted No.	Exposed to Advertisement, Weighted %	Marijuana Use, Weighted %	Prevalence of Marijuana Useb, Adjusted ORc (95% CI) [P Value]	Frequency of Marijuana Use in Last 30 Days Among Current Users, βd (SE) [P Value]
On storefronts
No	10,506	81.0	13.1	1 [Reference]	1 [Reference]
Yes	2,418	19.0	16.7	1.4 (1.2–1.6) [<.001]	0.1 (0.1) [.60]
Magazine or newspaper
No	9,772	75.9	12.0	1 [Reference]	1 [Reference]
Yes	3,093	24.1	19.7	1.6 (1.4–1.9) [<.001]	0.2 (0.1) [.19]
Billboard
No	10,813	83.4	13.3	1 [Reference]	1 [Reference]
Yes	2,089	16.6	16.2	1.4 (1.1–1.6) [.002]	0.1 (0.2) [.62]
Internet
No	6,024	47.2	9.7	1 [Reference]	1 [Reference]
Yes	6,850	52.8	17.6	1.8 (1.5–2.1) [<.001]	0.3c (0.1) [.04]
Television
No	8,740	67.9	12.3	1 [Reference]	1 [Reference]
Yes	4,142	32.1	17.0	1.4 (1.2–1.7) [<.001]	0.2 (0.1) [.18]
Radio
No	10,306	80.3	12.4	1 [Reference]	1 [Reference]
Yes	2,543	19.7	20.0	1.7 (1.5–2.0) [<.001]	0.2 (0.1) [0.09]

Abbreviations: CI, confidence interval; OR, odds ratio; SE, standard error.

^a Data sources: Johnston et al (19–22).

^b Students who reported no current use of marijuana were the reference group.

^c Models were adjusted for grade, sex, race/ethnicity, parental education, region, and population density.

^d The regression coefficient stands for a 0.3-unit increase in the scale (2–7) of marijuana use frequency. That is, participants exposed to marijuana advertisements from the internet had an average 0.3-unit increase in the scale of marijuana use frequency, which was coded as a continuous variable with 1 = 0 occasions, 2 = 1 or 2 occasions, 3 = 3–5 occasions, 4 = 6–9 occasions, 5 = 10–19 occasions, 6 = 20–39 occasions, and 7 = 40 or more occasions.