Supply Chains: A Manager's Guide

Feedback and Stability

In the systems discussed so far in this chapter, the signals all travel in the same direction, from the inputs toward the outputs. Although such systems exist, they are rare; most real-world systems have additional pathways that carry signals upstream as well, from outputs back to the inputs of earlier components (Figure 4.8). Such signals are called feedback because they feed information about the output back into the input, creating a loop in the system that wouldn't be there otherwise. Given that systems without feedback can be so hard to understand, adding a loop of this sort may seem like a perverse thing to do, but it turns out that the proper use of feedback is critical to producing useful, effective systems.

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