Comparing the impact of the OO-DFD and the Use Case methods for modeling functional requirements on comprehension and quality of models: a controlled experiment

Users' requirements of an information system are modeled in the analysis phase of the development process. The requirements can be modeled with various modeling methods. In this study, we compare two alternative methods for modeling the functional requirements: one is the UML Use Case (UC) model; the other is OO-DFD transaction (Object-Oriented DFD is a variant of DFD that includes data classes rather than "traditional" data stores). Each of these modeling methods consists of diagrams accompanied with narrative, semi-structured descriptions explaining their details. We conducted a controlled experiment that compared the comprehension of the two models (i.e., the diagrams and their descriptions) of a certain system and the quality of models created for a certain system with each of the two modeling methods. The main results of the experiment are that models created with the UC method are of better quality than models created with the OO-DFD transaction method because the former are simpler and less detailed; creating highly detailed models are error prone. Interestingly, in spite of the difference in the level of detail and structure, the experiment reveals no significant difference in comprehension of models of the two methods. The results call for improvement of the modeling methods in a way that considers the advantages of each of them, and thus we propose an improved method sketch that we call Enhanced Use Case, which will be evaluated in future work.