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. Author manuscript; available in PMC: 2012 Nov 1.
Published in final edited form as: J Child Adolesc Subst Abuse. 2011 Nov 1;20(5):407–420. doi: 10.1080/1067828x.2011.614873

Table 6.

Internal consistency between the recency of marijuana use question and the frequency of marijuana use question.

Substance Recency of last use
Frequency of 30 day No Use past 30 days n (%) Used past 30 days n (%) Total Inconsistencies Phi and Cramer's V
1994
No use past 30 days 124 (44.4) 5 (1.8) 55 (19.7) .646***
Used 1+ times past 30 days 50 (17.9) 100 (35.8)
1996
No use past 30 days 227 (41.5) 3 (0.5) 119 (21.7) .634***
Used 1+ times past 30 days 116 (21.2) 201 (36.7)
1998
No use past 30 days 302 (47.1) 4 (10.6) 121 (13.6) .669***
Used 1+ times past 30 days 117 (18.3) 218 (34.0)

* = p < .05

** = p < .01

***

p < .001