Analyzing the Behavior of Modelers in Interpreting Relationships in Conceptual Models: An Empirical Study Maria das Graças da Silva Teixeira, Ricardo de Almeida Falbo, Giancarlo Guizzardi, Ontology and Conceptual Modeling Research Group (NEMO) Federal University of Espírito Santo, Vitoria/ES, Brazil. maria.teixeira@ufes.br, {gguizzardi,falbo}@inf.ufes.br Abstract. This paper presents an experiment analyzing the behavior of model- ers in interpreting conceptual model fragments developed using an Ontology- Driven Conceptual Modeling Language (OntoUML). Our goal is to evaluate the effect of two ontological constructs (relator and role) in modeling relationships. Our hypotheses are: (i) the use of these constructs for modeling relations in- creases the clarity of the models; (ii) as a consequence, this increases the per- formance of modelers in interpreting these models. The behavior of the model- ers is evaluated considering the participants´ answers to predetermined ques- tions asked about two model fragments (compared with a template response). We also consider the rationale underlying the answers given by the participants. We have collected indications that both the role and the relator constructs in- fluence positively in the quality of the resulting interpretations. Keywords: Conceptual Model, Empirical Study, OntoUML, Relationship. 1 Introduction Despite its fundamental importance in conceptual modeling, there is evidence that the relationship construct and its modeling implications are still not fully understood by modelers. Wand, Storey and Weber [1] point out that, while both entities and relation- ships are fundamental to conceptual modeling, relationships prove to be more difficult to use. The lack of rigorously defined meaning of conceptual modeling constructs, especially in the case of the relationships, precludes the effective use of these con- structs. Empirical evidence shows that using relationships as a way to communicate the meaning of an application domain is often problematical [1] [2]. Most modelers have an intuitive understanding of what a relationship is. However, recognizing relationships in a real-world context, or correctly representing them in a model has proven to be challenging. There are various ways to represent a relation- ship [1], and modelers have to decide which one to use. In [3], Guizzardi provides a number of ontological theories, giving rise to the Uni- fied Foundational Ontology (UFO). UFO was used as basis for evaluating the Unified Modeling Language (UML) 2.0 metamodel, and for defining an ontologically well- founded UML profile for class diagrams, called OntoUML.