Data modeling and functional modeling: Examining the preferred order of using UML class diagrams and use cases

In the analysis phase of the information system development, the user requirements are studied, and analysis models are created. In most UML-based methodologies, the analysis activities include mainly modeling the problem domain using a class diagram, and modeling the user/functional requirements using use cases. Different development methodologies prescribe different orders of carrying out these activities, but there is no commonly agreed order for performing them. In order to find out whether the order of analysis activities makes any difference, and which order leads to better results, a comparative controlled experiment was carried out in a laboratory environment. The subjects were asked to create two analysis models of a given system while working in two opposite orders. The main results of the experiment are that the class diagrams are of better quality when created as the first modeling task, and that analysts prefer starting the analysis by creating class diagrams first.