2.4) Longer Feedback Loops

Feedback loops can also be made up of more than just two variables and links, e.g.:

In the example above, an increase in A will cause an increase in B, which in turn will increase C, which in turn decreases D, which in turn increases A. Following the logic like this shows that this loop acts as a positive feedback loop. The simple way to spot whether a longer loop is a positive or negative feedback loop is to count the negative connections: an even number gives a positive feedback loop, an odd number gives a negative feedback loop.