The majority of research regarding the effectiveness of object-oriented analysis and design (OOAD) is focused on a comparison of object-oriented to traditional approaches that highlights their relative strengths and weaknesses. There has been less focus on improving OOAD on its own. The standardization of the Unified Modeling Language (UML) creates an opportunity to focus on improving the methods of developing UML diagrams. Design quality can be a litmus test for overall system quality. Practice has shown that designing user interfaces before domain modeling can be used on a systematic basis to derive other UML diagrams for a large class of interactive information systems. This empirical study analyzed 43 OOAD projects to determine the effectiveness of the user interface driven system design (UIDD) by calculating defect densities for four UML diagrams. The study was performed on three levels: individual type of defect, type of diagram and entire project. Empirical results show that the UIDD consistently produced very low defect densities on all three levels for projects that varied widely with respect to application area, information system type, team experience and size.