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. 2011 Jul;72(4):592–601. doi: 10.15288/jsad.2011.72.592

Table 6.

Evidence for predictive validity: Prediction of abstinence from marijuana use and related problems and symptoms at 12 months from 6-month readiness

Variable 6RR
6SA
6SR
6STS
Estimate SE Estimate SE Estimate SE Estimate SE
12-month PDA
 Fixed effects
  Sex (1 = female, 2 = male) −1.85 7.84 −5.66 6.71 −5.55 6.82 −3.92 6.69
  Age −1.00 2.94 0.95 2.61 0.70 2.66 0.65 2.59
  Race (1 = White, 2 = other) −14.17 10.78 −15.72 9.38 −16.50 9.55 −18.12 9.34
  ADT: #inpt. + #residential days, last 30 days 1.42 0.87 1.43 0.69* 1.31 0.70 1.23 0.68
  6-month PDA, last 30 days 0.37 0.11** 0.30 0.12* 0.50 0.07** 0.37 0.09**
  6-month readiness 2.50 1.46 8.23 3.84* 0.66 2.81 8.04 3.06**
 Random effects
  Intercept (site differences) 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
  Residual 1,456.81 192.96** 1,346.73 162.13** 1,400.06 167.94** 1,334.25 160.05**
  n 114 138 139 139
12-month RMPI
 Fixed effects
  Sex 0.47 0.38 0.47 0.33 0.58 0.34 0.45 0.33
  Age −0.10 0.14 −0.11 0.13 −0.05 0.13 −0.07 0.13
  Race 0.00 0.52 0.36 0.45 0.67 0.47 0.64 0.45
  ADT 0.09 0.04* 0.05 0.03 0.04 0.03 0.05 0.03
  6-month RMPI 0.07 0.01** 0.07 0.01** 0.08 0.01** 0.08 0.01**
  6-month readiness −0.18 0.06** −0.48 0.11** 0.08 0.15 −0.34 0.12**
 Random effects
  Intercept 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
  Residual 3.23 0.44** 2.92 0.36** 3.27 0.40** 3.09 0.38**
  n 106 129 131 131
12-month DSMS
 Fixed effects
  Sex 0.50 0.34 0.33 0.28 0.40 0.29 0.32 0.29
  Age 0.06 0.13 0.05 0.11 0.09 0.11 0.08 0.11
  Race 0.07 0.45 0.22 0.38 0.35 0.40 0.34 0.39
  ADT 0.03 0.04 0.02 0.03 0.02 0.03 0.02 0.03
  6-month DSMS 0.39 0.08** 0.38 0.07** 0.48 0.07** 0.46 0.07**
  6-month readiness −0.13 0.05** −0.35 0.10** 0.06 0.12 −0.20 0.11
 Random effects
  Intercept 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
  Residual 2.59 0.35** 2.27 0.27** 2.43 0.29** 2.38 0.29**
  n 112 136 138 138

Notes: ns differ because of missing data, and parameter estimates are unstandardized. A square root transformation was applied to the Rutgers Marijuana Problem Index (RMPI) and alcohol and other drug treatment (ADT) data. 6RR = 6-month Readiness Ruler; 6SA = 6-month Staging Algorithm; 6SR = 6-month SOCRATES Recognition; 6STS = 6-month SOCRATES Taking Steps; PDA = percentage of days abstinent, measured by use of the Timeline Followback Interview and references 30 days before the interview date; inpt. = inpatient; DSMS = Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, marijuana abuse and dependence symptom count.

*

p≤.05;

**

p≤.01.