Do Architectural Design Decisions Improve the Understanding of Software Architecture? Two Controlled Experiments

Architectural design decision (ADD) and its design rationale, as a paradigm shift on documenting and enriching architecture design description, is supposed to facilitate the understanding of architecture and the reasoning behind the design rationale, which consequently improves the architecting process and gets better architecture design results. But the lack of empirical evaluation that supports this statement is one of the major reasons that prevent industrial practitioners from using ADDs in their daily architecting activities. In this paper, we conducted two controlled experiments, as a family of experiments, to investigate how presence of ADDs can improve the understanding of architecture. The main results of our experiments are: (i) using ADDs and their rationale in architecture documentation does not affect the time needed for completing architecture design tasks; (ii) one experiment and the family of experiments achieved a significantly better understanding of architecture design when using ADDs; and (iii) with regard to the correctness of architecture understanding, more experienced participants benefited more from ADDs in comparison with less experienced ones.