A mediator variable acts as an intermediary in the causal connection of some predictor(s) and the corresponding outcome(s). Hence, a mediator is affected by the predictor(s) and influences the outcome(s) simultaneously. In the ViePHEP the mediator variables are perceived access to, affordability and provision of health care, as well as justice-fairness attitudes.

For both solely partial mediation is assumed. This means that the predictor variables exert influence on the outcomes both immediately and through the mediators. Therefore, the mediators add value to understand the variables’ relationships in a more complete way. Yet, the mediators are not necessarily required to explain said relationships in a less complete and more partial way.