Figure 1:
The figure illustrates the concepts theory, target system, data, and data model. The target system is the system consisting of interacting components that gives rise to phenomena. Phenomena are robust features of the world captured by data models. Theories represent the structure of the target system, proposing a set of components C and the relations among them and positing that they give rise to the phenomena. Data for variables V are obtained by taking measurements of the components of the target system.