The unique mediating effects of nicotine exposure and changes in cigarettes per day on alcohol use. Abbreviations include TNE (total nicotine equivalents), CPD (cigarettes per day), BSL (baseline), WK (week), and VLNC (very low nicotine content cigarettes). The change in alcohol use and CPD from baseline to week 2 and weeks 2 to 6 (represented by corresponding circles in the figure) were estimated using piecewise latent growth curve models. The resulting model demonstrated adequate fit (χ2 = 478.80, p < 0.001; RMSEA = 0.07, 90% CI: 0.06, 0.08, CFI = 0.95, TFI = 0.94). Several variables and pathways were excluded from the diagram to simplify the figure, including the following: Intercepts of CPD and alcohol use were allowed to correlate with each other and predicted the slope terms of the parallel process; baseline TNE was included as a covariate for effects on weeks 2 and 6 TNE and change in alcohol use, and the relations of all other covariates with TNE, changes in CPD, and alcohol use including gender, FTND score (minus CPD), minority status, and age.