Step 5, the estimation of the overall, mediating, and direct effects, was based on the final
model in Figure 2, where the overall total effect was equal to the estimated overall mediated
effect (effect of psychosocial conditions on safety behaviour mediated by safety climate).
Since there is no available method for testing mediation in four measurement waves,
mediation was tested in each link of the causal chain (Taylor, MacKinnon, & Tein, 2007). The
overall mediated effect between T1 and T4 consisted of three pathways, which were all
significant. The sum of three products of the standardized regression weights in the three
pathways was .047, constituting the overall mediated effect in the final model.