Kathy Kotiadis

Conceptual modelling: knowledge acquisition and model abstraction

Conceptual modelling has gained a lot of interest in recent years and simulation modellers are particularly interested in understanding the processes involved in arriving at a conceptual model. This paper contributes to this understanding by discussing the artifacts of conceptual modelling and two specific conceptual modelling processes: knowledge acquisition and model abstraction. Knowledge acquisition is the process of finding out about the problem situation and arriving at a system description. Model abstraction refers to the simplifications made in moving from a system description to a conceptual model. Soft Systems Methodology has tools that can help a modeller with knowledge acquisition and model abstraction. These tools are drawing rich pictures, undertaking analyses `one¿, `two¿, `three¿, and constructing a root definition and the corresponding purposeful activity model. The use of these tools is discussed with respect to a case study in health care.

Conceptual Modeling for Discrete-Event Simulation

Bringing together an international group of researchers involved in military, business, and health modeling and simulation, Conceptual Modeling for Discrete-Event Simulation presents a comprehensive view of the current state of the art in the field. The book addresses a host of issues, including: What is a conceptual model? How is conceptual modeling performed in general and in specific modeling domains? What is the role of established approaches in conceptual modeling? Each of the books six parts focuses on a different aspect of conceptual modeling for simulation. The first section discusses the purpose and requirements of a conceptual model. The next set of chapters provides frameworks and tools for conceptual modeling. The book then describes the use of soft systems methodology for model structuring as well as the application of software engineering methods and tools for model specification. After illustrating how conceptual modeling is adopted in the military and semiconductor manufacturing, the book concludes with a discussion on future research directions. This volume offers a broad, multifaceted account of the field by presenting diverse perspectives on what conceptual modeling entails. It also provides a basis upon which these perspectives can be compared.

A participative modelling framework for developing conceptual models in healthcare simulation studies

Conceptual modelling, one of the first stages in a simulation study, is about understanding the situation under study and deciding what and how to model. We argue that stakeholder involvement as part of conceptual modelling could lead to a more successful simulation study with better prospects for implementation. Our work is mainly applied in health care studies, which are characterized by many stakeholders with multiple views and objectives and often a politically charged environment. We develop a participative conceptual modelling framework, which uses tools from soft systems methodology, a problem structuring approach. The benefit of this approach lies in that it supports the conceptual modelling process by engaging stakeholders in a structured and participative way. It involves facilitated workshops, using a set of tools developed. A case study of the conceptual modelling process undertaken for an obesity system is provided to illustrate the proposed framework and tools.

Learning from discrete-event simulation: Exploring the high involvement hypothesis

Discussion of learning from discrete-event simulation often takes the form of a hypothesis stating that involving clients in model building provides much of the learning necessary to aid their decisions. Whilst practitioners of simulation may intuitively agree with this hypothesis they are simultaneously motivated to reduce the model building effort through model reuse. As simulation projects are typically limited by time, model reuse offers an alternative learning route for clients as the time saved can be used to conduct more experimentation. We detail a laboratory experiment to test the high involvement hypothesis empirically, identify mechanisms that explain how involvement in model building or model reuse affect learning and explore the factors that inhibit learning from models. Measurement of learning focuses on the management of resource utilisation in a case study of a hospital emergency department and through the choice of scenarios during experimentation. Participants who reused a model benefitted from the increased experimentation time available when learning about resource utilisation. However, participants who were involved in model building simulated a greater variety of scenarios including more validation type scenarios early on. These results suggest that there may be a learning trade-off between model reuse and model building when simulation projects have a fixed budget of time. Further work evaluating client learning in practice should track the origin and choice of variables used in experimentation; studies should also record the methods modellers find most effective in communicating the impact of resource utilisation on queuing.

Model reuse versus model development: effects on credibility and learning

The construction of generic models and their validity when reused has received much attention in the DES literature. This is with good reason as rapid deployment of a generic model can reduce time, effort and cost of a study. On the other hand the utility of model reuse as an aid to decision making has had little exploration. This is an area that should be considered as the literature on learning from just simulation model use provides contradictory evidence on its effectiveness. This paper proposes that development of models with some client involvement has alternative benefits to reusing a model: improved learning and understanding for clients. To explore this proposition an experimental design to compare how model reuse and model development affect learning in DES studies is presented. Some preliminary thoughts, based on pilot experiments, on the client process of credibility assessment and understanding of resource utilisation are discussed.

Facilitated conceptual modelling: practical issues and reflections

This paper discusses some practical issues relevant to facilitated conceptual modelling (CM). We consider facilitated CM as a process of undertaking CM primarily in facilitated workshops attended by a group of stakeholders. Facilitated workshops are a common practice in some fields of operational research (OR), System Dynamics (SD) and Problem Structuring Methods (PSM). The associated benefits of involving the stakeholders in the modelling process are reported in the literature such as enabling the mutual exploration of the problem situation and creating a strong ownership of the formulated problem. Further benefits related to CM are knowledge acquisition from domain experts, conflict resolution, fostering credibility and creativity. Reflecting on our experience, we consider the practical issues related to undertaking facilitated CM such as the group size and composition, team roles and the facilitator and the organization of workshops. The ideas put forward could be useful to modellers interested in undertaking facilitated CM.