Abstract:
It is generally recognized that conceptual modeling is one of the most vital parts of a simulation study. At the same time, it also seems to be one of the least understood. A review of the extant literature on conceptual modeling reveals a range of issues that need to be addressed: the definition of conceptual model(ling), conceptual model requirements, how to develop a conceptual model, conceptual model representation and communication, conceptual model validation, and teaching conceptual modeling. It is clear that this is an area ripe for further research, for the clarification of ideas and the development of new approaches. Some areas in which further research could be carried out are identified.
Introduction:
Conceptual modeling is the abstraction of a model from a real or proposed system. This process of abstraction involves some level of simplification of reality (Zeigler 1976). Effective conceptual modeling requires that the abstraction is an appropriate simplification (Pidd 2003).
Put in these terms, conceptual modeling is probably the most important aspect in the process of developing and using simulation models. The design of the model impacts all aspects of a simulation study, in particular the data requirements, the speed with which the model can be developed, the validity of the model, the speed of experimentation and the confidence that is placed in the model results. A well designed model significantly enhances the likelihood of a successful outcome to a simulation study.
Although effective conceptual modeling is vital, it is also the most difficult and least understood stage in the modeling process (Law 1991). There is surprisingly little written on the subject. It is difficult to find a book that devotes more than a handful of pages to the design of the conceptual model. Neither are there a plethora of research papers, with only a handful of well regarded papers over the last four decades. A search through the academic tracks at major simulation conferences on discrete-event simulation reveals a host of papers on other aspects of simulation modeling. There are, however, very few papers that give any space to the subject of conceptual modeling.
This paper aims to outline the key issues in conceptual modeling for simulation. Based on a review of the current literature in the field a series of issues are identified. The aim is not to address these issues here. The hope is that in identifying the issues and the extent to which they have (and in most cases have not) been addressed, a research agenda for conceptual modeling might emerge. The issues are discussed under the following headings:
It should be noted that the prime interest of the author is in discrete-event simulation and its application to aiding organisational change. This generally involves medium sized simulation studies (weeks or months), with models developed in commercial-off-the-shelf packages. These models are often developed by a lone modeler and thrown away at the end of the simulation study (Robinson 2002).
Summary of Research Requirements:
The discussion above identifies a set of issues that need to be addressed in order to develop the field of conceptual modeling for simulation (and modeling more generally). These issues include:
It is believed that these issues should form the basis for a research agenda in conceptual modeling for simulation.