A core activity in information systems development involves building a conceptual model of the domain that an information system is intended to support. Such models are created using a conceptual-modeling (CM) grammar. Just as high-quality conceptual models facilitate high-quality systems development, high-quality CM grammars facilitate high-quality CM. This paper provides a new perspective on ways to improve the quality of the semantics of CM grammars. For many years, the leading approach to this topic has relied on ontological theory. We show, however, that the ontological approach captures only half the story; it needs to be coupled with a logical approach. We explain how the ontological and logical qualities of CM grammars interrelate. Furthermore, we outline three contributions of a logical approach to evaluating the quality of CM grammars: a means of seeing some familiar CM problems in simpler ways, illumination of new problems, and proving the benefit of modifying existing CM grammars in particular ways. We demonstrate these benefits in the context of the Entity-Relationship grammar. More generally, our paper opens a new area of research with many opportunities for future research and practice.
Allen and March provide a critique of one of our papers in which we argue composites should be represented as entities/objects in a conceptual model rather than relationships/associations (Shanks et al. 2008). They contend we have addressed a non-issue. Furthermore, they argue our theoretical rationale and empirical evidence have flaws. In this paper, we provide a response to their arguments. We show that the issue we address is substantive. We show, also, that our theoretical analysis and empirical results are robust. We find, instead, that Allen and March's theoretical arguments and empirical evidence have flaws.
The part-of construct is a fundamental element of many conceptual modeling grammars that is used to associate one thing (a component) with another thing (a composite). Substantive theoretical issues surrounding the part-of construct remain to be resolved, however. For instance, contrary to widespread claims, some researchers now argue the relationship between components and composites is not always transitive. Moreover, how the part-of construct should be represented in a conceptual schema diagram remains a contentious issue. Some analysts argue composites should be represented as a relationship or association. Others argue they should be represented as an entity. In this paper we use an ontological theory to support our arguments that composites should be represented as entities and not relationships or associations. We also describe an experiment that we undertook to test whether representing composites as relationships or entities enables users to understand a domain better. Our results support our arguments that using entities to represent composites enables users to better understand a domain.
Within the information systems field, the task of conceptual modeling involves building a representation of selected phenomena in some domain. High-quality conceptual- modeling work is important because it facilitates early detection and correction of system development errors. It also plays an increasingly important role in activities like business process reengineering and documentation of best-practice data and process models in enterprise resource planning systems. Yet little research has been undertaken on many aspects of conceptual modeling. In this paper, we propose a framework to motivate research that addresses the following fundamental question: How can we model the world to better facilitate our developing, implementing, using, and maintaining more valuable information systems? The framework comprises four elements: conceptual-modeling grammars, conceptual-modeling methods, conceptual-modeling scripts, and conceptual-modeling contexts. We provide examples of the types of research that have already been undertaken on each element and illustrate research opportunities that exist.
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 relationship 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 diagrams 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 understanding 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 semantics. We describe three experiments which we then undertook to test our predictions. The results of the experiments support our predictions.
Alongstanding debate in the data modeling literature pertains to whether the grammars used to generate conceptual schemas should sustain a distinction between entities and attributes. The grammars used to generate entity-relationship diagrams and object-oriented conceptual models, for example, provide separate constructs for representing entities and attributes. The grammars used to generate binary data models, however, provide only a single construct for representing both entities and attributes. To sharpen the focus of the debate, a multi-trial free-recall experiment was conducted with database designers who had been trained primarily in a binary conceptual schema design methodology. In the experiment, the designers were first shown conceptual schema diagrams based on a binary model. The designers were then asked to recall the diagrams. Throughout their training as designers, they had been admonished to eschew any distinction between entities and attributes. Moreover, the diagrams they were shown in the experiment did not make a distinction between entities and attributes. Their recall protocols seemed to show, however, that they were considering some elements of the diagrams to be entities and others to be attributes Their memory structures appear to reflect, therefore, that they perceive entities and attributes to be two distinct constructs.
Three types of diversity have been prominent in the Information Systems discipline for over a decade: (a) diversity in the problems addressed; (b) diversity in the theoretical foundations and reference disciplines used to account for IS phenomena; and (c) diversity in the methods used to coiled, analyze, and interpret data. History has played a major part in encouraging IS researchers to use diversity as a means of countering criticisms of their discipline and increasing their research rigor and productivity. In particular, frequent recourse to reference disciplines has underpinned much of the research that has been undertaken since the early 1980s. There are now signs, however, that the level of diversity that currently exists in IS research may be problematic. In this paper, we consider some of the benefits and costs of allowing, diversity to reign in the IS discipline. We also propose a structure that we hope will facilitate discourse on the benefits and costs of diversity and on the role that diversity should now play in the IS discipline.