Complex social systems are unpredictable on the level of the individual actor. They are, however, somewhat stable and predictable on the level of their emerging structure. Hence, systemic change can be defined as transformations in the structure of a system. Positive transformations enable individuals to do things they could not have done before. In this way, the changes contribute to the development of the system.
Systems never exist in isolation. While a system can show consistent new patterns of behaviour locally, it can be forced back into a previous pattern by its environment over time. Changes can only be sustained if they reach a critical mass. One way to get some indication on whether the change is going to sustain is to look at the scale or spread of change. Scale not in a sense of bare numbers of people, but rather in a sense of a process of change spreading through a series of open systems.