how do the [theory] constructs interact … How are the constructs related? Relationships between constructs make up a theory’s propositions, and describe how the constructs interact. Constructs and their relationships are the basic constituents of all five types of theory above. Describing how things are related may give rise to predictions (Type III and Type IV theories).

D. I. K. Sjøberg, T. Dybå, B. C. D. Anda, and J. E. Hannay, “Building Theories in Software Engineering,” in Guide to Advanced Empirical Software Engineering SE - 12, F. Shull, J. Singer, and D. K. Sjøberg, Eds. Springer London, 2008, pp. 312–336. [Springerlink]