Conceptual modeling is an important task undertaken during the systems development process to build a representation of those features of an application domain that are important to stakeholders. In spite of its importance, however, substantial evidence exists to show that it is not done well. Designers often provide incomplete, inaccurate, or inconsistent representations of domain features in the conceptual models they prepare. Users often have difficulty understanding the meaning inherent in a conceptual model. In this paper, we investigate the proposition that part of the difficulties that stakeholders experience with conceptual modeling arises when a conceptual modeling grammar or a representation produced using the grammar lacks ontological clarity. Lack of ontological clarity arises when a one-one mapping does not exist between conceptual modeling constructs and real-world constructs. For example, the grammatical construct of an entity is used to represent both things and events in the real world. Specifically, we focus on the grammatical construct of a relationship with attributes, which is often used in entity-relationship modeling. We argue that use of this construct produces ontologically unclear representations of a domain. We also report results from an experiment we undertook where we investigated the impact of using relationships with attributes in conceptual modeling representations on the problem-solving performance of users of these representations. Consistent with our predictions, we found that using relationships with attributes undermined problem-solving performance in unfamiliar domains. Contrary to our predictions, however, their use did not undermine problem-solving performance in familiar domains
