«Rogers (1962) identified five types of adopters, the first two being catalytic ‘Change Agents’: innovators (2.5% on average), early adopters (13.5%), members of the early majority (34%), members of the late majority (34%), and laggards (16%).» Lehman, 2004:709

«We should note that ‘50 percent’ follows from Rogers’ diffusion of innovations model: the first three categories together (innovators 2.5%, early adopters 13.5%, and members of the early majority 34%) equal precisely 50 percent. Certainly, when half the public uses a medium we can safely say that it is no longer marginal.? (Lehman, 2004:714)