Next, we tested if the full model was a more robust predictor of smoking status at week 12 than either the nicotine-applicable model or the negative-reinforcement model using logistic regression analyses. Analyses were conducted as follows: (i) both the nicotine-applicable model and the negative-reinforcement model were estimated; (ii) the remaining DSM-IV items missing from each model were added to the nicotine-applicable model and negative-reinforcement model; thus, each resulting in the same full model; (iii) the full model was estimated and the change in goodness-of-fit upon the addition of the remaining items to nicotine-applicable model and the negative-reinforcement model was tested. These analyses represented the tests of predictive validity of the three models.
