Essential and incidental complexity in requirements models

A deep understanding of the complexity of the requirements model and its dynamics is critical in improving requirements engineering process management. Findings from an action research study an insightful explanation of how the complexity of the requirements model evolves over time. We argue that there are two different types of complexity of the model: the essential and incidental complexities. The essential complexity represents the inherent understanding of the problem space while the incidental complexity arises from the poor fit between the structure of the model and the structure of the world which the model aims to represent. We present a pattern for the dynamics of changes in the complexity of the requirements model. The evolution of the requirements model involves both the growth of the essential complexity throughout the discovery of the problem space and the growth and shrinkage of the incidental complexity, as the model undergoes a large number of changes. The new understanding of the complexity of the requirements model and its dynamics draws new directions for future research and forms a basis for a new approach to process management.