As a cautionary note, stratifying models by assessment wave is appropriate for calculating effect sizes of the original mixed-effects regression model only because the original model (1) used time as a categorical variable (due to the irregular intervals between assessment waves) and (2) allowed smoking quantity and nicotine dependence to vary over time (i.e., included interactions between these variables and time). Had time been continuous or the regressors had not been allowed to vary over time, the effect sizes in Table 4 would be less consistent with the original model, possibly resulting in inaccurate estimates of effect size.
