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. Author manuscript; available in PMC: 2013 Nov 21.
Published in final edited form as: J Subst Abuse Treat. 2005 Jun;28(4):10.1016/j.jsat.2005.02.004. doi: 10.1016/j.jsat.2005.02.004

Table 2.

Mean motivation at baseline and follow-up for intervention and control conditions (n = 30)

Assessment Assessment only
Assessment plus brief intervention
Effect size (95% CI)
n M SD n M SD
Baseline 15 79.5 21.2 15 82.5 18.9
Follow-up 15 77.4 20.0 15 88.8 10.0 .49 (−0.25 to 1.20)

Effect size is based on change scores using the formula d = M1 − M2 /σpooled. Values at follow-up are based on intent-to-treat analysis, carrying baseline values forward for eight participants lost to follow-up.