The discussion about predicting human behavior as to how and when people buy is often diverted to the Diffusion of Innovations.
Diffusion of Innovations is a theory that seeks to explain how, why, and at what rate new ideas and technology spread through cultures. How and when people buy products or services is thought to be affected by this theory. Everett Rogers, a professor of rural sociology, popularized the theory in his 1962 book Diffusion of Innovations.