ABSTRACT
So far, we have considered only recursive models, models with flow graphs that have no loops, no feedback, and no reciprocal effects between pairs of variables. We will now consider nonrecursive models with loops. I base much of this section on material in Heise’s (1975) Causal Analysis. But an excellent source is also given in Chen (1983) and in the introduction to Wyatt (2004). A connected series of causal arrows that begins and ultimately ends at the same variable is a loop. In Figure 14.1, we show some basic kinds of loops in nonrecursive models.
