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. Author manuscript; available in PMC: 2018 Apr 1.
Published in final edited form as: Drug Alcohol Depend. 2017 Feb 3;173:117–125. doi: 10.1016/j.drugalcdep.2016.11.040

Table 1. Mean marijuana use days at baseline, 6-, 12-, 18-, and 24-month follow-ups based on trajectory group membership.

Assessment Low (n=169, 28.2%) Intermittent (n=97, 16.2%) Moderate Decline (n=72, 12.0%) High Decline (n=79, 13.2%) Chronic (n=182, 30.4%)
Baseline Cannabis 18.3 (25.1) 34.8 (33.7) 51.8 (32.9) 60.9 (32.4) 71.0 (29.5)
6-month Cannabis 2.2 (3.2) 6.8 (8.1) 41.7 (26.7) 61.3 (32.6) 71.8 (26.0)
12-month Cannabis 1.8 (3.5) 16.0 (18.8) 8.9 (11.5) 64.0 (31.2) 73.4 (27.1)
18-month Cannabis 3.2 (6.5) 43.0 (34.8) 6.4 (7.9) 56.0 (33.9) 73.0 (28.5)
24-month Cannabis 1.1 (2.2) 53.1 (31.4) 6.1 (9.8) 6.9 (9.9) 81.9 (16.3)

Note: Values are Mean (SD). Because marijuana use was measured for the past 30 days at baseline, and the past 90 days at each follow-up, the value for baseline days was multiplied by 3 to standardize the days presented for descriptive purposes; n= 599 (baseline), n=512 (6-month), n=502 (12-month), n=505 (18-month) and n=512 (24 month).