1. A computer-implemented method comprising: via a visual display of a first model from a plurality of models comprising a causal model, an activity model, and a dimensional report model, rendering a plurality of variables, each of said plurality of variables linked together by model element links between each said plurality of models, each model element link rendered as a link symbol, said plurality of variables comprising at least one of a process metric and a control variable, wherein: user selection of a link symbol of a first link associated with a first variable of said plurality of variables and rendered via said first model is adapted to cause said first variable to be rendered via a second model from said plurality of models, said first link uniquely indicative of the particular model from said plurality of models to which said first link is directed; if said second model is adapted to render a plurality of instances of said first variable, selection of said link symbol of said first link is adapted to cause a user-selectable list of said plurality of instances to be rendered; and user selection of said link symbol of said first link is adapted to cause each instance of said first variable to be highlighted in a rendering of said second model.