It should be noted that a large proportion of the variance in craving and drinking were accounted for by between-person differences (see Supplemental Appendix). The remaining variance at the within-person level was smaller by comparison. In addition, our results showed that the magnitude of the effect was much larger across individuals, or at the between-level albeit with more variation, than at the daily or within-level in both studies. It may be that small deviations in the within-person motivational state that are sustained over the day are adequate to affect drinking behavior. However, craving can fluctuate over time and individuals vary extensively in their reports (Shiffman, 2000). By separately modeling the between- and within-person components, we could not only identify who is more at-risk for drinking while in treatment, but also when they would be most at risk. An additional strength of this study was the time-locked nature of the mediation tested in these analyses. Although stress and craving were measured simultaneously, others have found that end-of-day stress reports were comparable to stressful events reported at the moment that the event
