Metcalfe's Law

How to use it. As a rough prior on network effects. Small additions to a small network are minor. Small additions to a large network are not. Use it to argue for getting to scale rather than holding steady.

How it gets misused. Quoted as if it were a law of physics. The exact shape is contested. Some research supports n², some supports n·log(n), and the truth depends on the network and the value being measured. Use the shape of the curve and ignore the exact exponent.