The idea
Two reasons anyone buys a new thing
A phone launches. Nobody owns one. A year later everybody does. What happened in between?
- Some people bought because they saw the advert. They would have bought even if they knew nobody who owned one.
- Far more people bought because a friend showed them theirs.
The first group is small and steady. The second group grows as more friends own one, then shrinks again once almost everyone already has one.
Add the two together and you get the shape every new product follows: slow, then steep, then a peak, then a long tail. The Bass model is that shape written as three numbers.