Models of structural change should be able to explain constancy as well as change, must combine micro- and macrolevel analysis, and must encompass endogenous sources of change. It is necessary to distinguish among three levels of structure of a system: output structure, parameter structure, and process structure. With these concepts four basic types of change processes can be indentified: simple reproduction, extended reproduction, transition, and transformation. These are discussed and illustrated, as well as some important special cases such as dialectical change, overintegration, and catastrophe.
Gudmund Hernes (Mon,) studied this question.