Authors: Arvind Patel, François Bodart, Marc Sim, Ron Weber
Tags: 2001, conceptual modeling
An important feature of some conceptual modelling grammars is the features they provide to allow database designers to show real-world things may or may not possess a particular attribute or relationship. In the entity-relationship model, for example, the fact that a thing may not possess an attribute can be represented by using a special symbol to indicate that the attribute is optional. Similarly, the fact that a thing may or may not be involved in a relation- ship can be represented by showing the minimum cardinality of the relationship as zero. Whether these practices should be followed, however, is a contentious issue. An alternative approach is to eliminate optional attributes and relationships from conceptual schema dia- grams by using subtypes that have only mandatory attributes and relationships. In this paper, we first present a theory that led us to predict that optional attributes and relationships should be used in conceptual schema diagrams only when users of the diagrams require a surface-level imderstanding of the domain being represented by the diagrams. When users require a deep-level understanding, however, optional attributes and relationships should not be used because they undermine users’ abilities to grasp important domain se- mantics. We describe three experiments which we then undertook to test our predictions. The results of the experiments support our predictions.Read the full paper here: https://www.informs.org/Publications/INFORMS-Journals/Information-Systems-Research
