Figure A6.

Results of (A) the CLPM (with means and covariates) and (B) the best-fitting IV-CLPM (with means and covariates) examining bidirectional causal effects between smoking status (Smk) and alcoholic drinks per week (Alc), assessed three years apart. The paths have been labeled with the point estimate and its standard error (in parentheses). The dashed path in the CLPM indicates a non-significant causal estimate. The CLPM suggests a likely unidirectional causal process, with a significant effect of smoking on alcohol use, but not vice versa. On the contrary, the IV-CLPM suggests a more complex bidirectional causation, with a significant proximal effect of alcohol use on smoking, which, in turn, has a reciprocal distal effect on alcohol use. In both path diagrams, squares/rectangles represent the observed variables, and circles represent latent variables. Triangles represent constants used to model the traits’ mean levels.