, Direct effect: one or more predictors pointing at an outcome. The simplest defensible model, and often the right one.
, Mediation: predictor to mediator to outcome, used when you are claiming a mechanism rather than just an association.
, Moderation: a variable drawn onto the arrow between predictor and outcome, indicating that the relationship changes strength or direction depending on its level.
, Moderated mediation: a mechanism whose strength itself depends on a third variable. Powerful, and the fastest way to make a figure unreadable if drawn carelessly.
, Input-process-output: a left-to-right model favoured in education, operations, and evaluation research.
, Cyclical or feedback: outcomes that loop back onto inputs, common in systems, organisational, and qualitative work.
, Nested or multi-level: constructs grouped by level, such as individual inside team inside organisation, with cross-level arrows made explicit.