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. Author manuscript; available in PMC: 2013 Mar 11.
Published in final edited form as: Am J Psychiatry. 2010 May 17;167(8):987–993. doi: 10.1176/appi.ajp.2010.09020189

Table 2.

Stability and prevalence of cannabis use (users versus non-users): tetrachoric correlations

Baseline (N=225) Month 6 (N=184) Year 2 (N=166) Year 4 (N=143) Year 10 (N=162)
Stability ---
 Baseline
 6-month 0.70 ---
 2-year 0.51 0.73 ---
 4-year 0.48 0.75 0.74 ---
 10-year 0.66 0.52 0.45 0.78 ---
Prevalence
 Users, N (%) 23 (10.2) 26 (14.1) 30 (18.1) 19 (13.3) 16 (9.9)
 Non-users, N (%) 202 (89.8) 158 (85.9) 136 (81.9) 124 (86.7) 146 (90.1)

Note: Cannabis status was assessed for the past 30 days at Baseline and at 10 years, and it was assessed for the past six months at the 6-month, 2-year, and 4-year points.