Fig. 1.

Multilevel growth curve model with time-invariant and time-varying covariates, including drinking motives as individual-level factors and the cross-level interaction effect between individual drinking motives and the impact of friends (interaction model). T1–T5 time points 1 to 5 (8 p.m. to 12 a.m.), D1–D5 hourly alcohol consumption rate at every time point, F1–F5 number of friends present at every time point, Saturday was used as reference category on the evening level. The latent variable “Situational impact of friends” represents the random slope for the outcome “hourly alcohol consumption rate” which is regressed on the “number of friends” at every time points 1–5. The arrows from each of the drinking motives to the latent variable “Situational impact of friends” represent the cross-level interaction to test if the effect of “number of friends” on “hourly alcohol consumption rate” varies by participants’ scores on the different drinking motives