Relationships of confounders and mediators for the association of maternal race and persistent wheeze. 1A, Diagram representing complex interactions between potential confounders and possible mediators of the relationship between maternal race and persistent wheeze. 1B, Mediation framework for statistical conditions that must be satisfied to be considered a mediator. In formal mediation analysis:
(1) represents the direct effect of maternal race on persistent wheezing illness
(2 and 3) represents the indirect effect of maternal race through a mediator.