A moderator model is operative when the strength or direction of a relation
between two variables varies as a function of a third variable, called the
moderator variable. The moderator need not affect the outcome variable
itself. Rather, it represents a set of conditions that qualify the relation
between two or more other variables.
A mediational model is operative when one variable affect a second (outcome)
variable only indirectly, through an intermediate step or process, represented
by a third variable, called the mediator variable. The mediator variable is
simultaneously conceived as being a consequence of the first variable and a
cause of the outcome variable. In a completely mediational model, the entire
effect of the first variable on the outcome variable is translated through the
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