An Update on a Successful Simulation Project: The UNOS
Liver Allocation Model
Ann M. Harper, Sarah E. Taranto, Erick B. Edwards, and O. Patrick Daily (United Network for Organ Sharing)
The UNOS Liver Allocation Model (ULAM) is a simulation of the cadaveric liver allocation system in the United States. ULAM was created by the United Network for Organ Sharing (UNOS) in collaboration with Pritsker Corporation/Symix Systems, to permit comparison of multiple liver allocation policy proposals so that policies can be tested prior to implementation. ULAM is extremely adaptable, and with it UNOS has been able to respond to varied and complex requests for policy analysis. ULAM has aided UNOS throughout the highly publicized national liver allocation debate, and its use is anticipated for the foreseeable future. The authors believe that ULAM is an excellent example of simulation technology used to resolve national medical policy issues. The success of ULAM, in terms of its ease of use, flexibility of design, and acceptance by the transplant community, has reinforced UNOS' desire to create other organ allocation models. This paper provides a brief description of ULAM's structure, and summarizes the evolution of ULAM from 1995 to 2000.
Using Simulation for the Economic Evaluation of Liver
Lynne P. Baldwin, Tillal Eldabi, and Ray J. Paul (Brunel University) and Andrew K. Burroughs (Royal Free Hospital)
This paper demonstrates the use of simulation in an evaluative study for the technology of liver transplantation from cost-effectiveness point of view. This study is conducted in the United Kingdom where there are no explicit guidelines for the prioritization of patients waiting for transplantation. Another objective of the model is to enable health economists to understand the technology of liver transplantation and evaluate alternative policies for prioritizing patients in the waiting list. The paper shows the construction of a tailor-made package (LiverSim) and provides an example of how this package is used by the stakeholders to assist in the evaluation process. Some final lessons are drawn that simulation helps in exploring more issues outside the boundaries of quantitative results.
Developing a National Allocation Model for Cadaveric
Sarah E. Taranto, Ann M. Harper, Erick B. Edwards, John D. Rosendale, Maureen A. McBride, and O. Patrick Daily (United Network for Organ Sharing), Dan Murphy, Bill Poos, and Janet Reust (Symix Systems) and Bruce Schmeiser (Purdue University)
The UNOS Kidney Allocation Model (UKAM) is a software tool for the simulation and analysis of national cadaveric kidney and kidney-pancreas allocation policies for transplantation. UKAM is modular and is designed to enable easy updating of the various components as new data become available. UKAM’s flexibility gives the user the ability to create and evaluate an almost infinite number of detailed allocation policies. This will enable the United Network for Organ Sharing (UNOS) to make decisions based on quantitative data when considering changes in organ allocation policies.
A Simulation Study of the Radiology Department at
Martha A. Centeno (Florida International University), Cristina Albacete (Florida Power and Light), Diego O. Terzano (Florida International University) and Manuel Carrillo and Tom Ogazon (Jackson Memorial Hospital)
This paper discusses a study of the Radiology department at Jackson Memorial Hospital. The animated simulation model was fed data from the operations database. Several inefficiencies were identified, and suggestions for improvement were explored. These adjustments included six scenarios: 1) Current system, 2) Modeling each procedure to take place with the assistance of only one technologist, 3) Modeling each procedure to take place with the assistance of two technologists, 4) Addition of a new Neurological operating room, 5) Addition of a designated pre-holding area for the patients' comfort, and 6) One-day extension in the weekly operating schedule. It was identified that under scenario 2 (one technologist) the total time in the system was significantly lower than the current system and scenario 3 (two technologists). However, this scenario also gave the lowest utilization rate for the eight technologists and the lowest utilization rate for the operating rooms. To increase efficiency, other recommendations were made.
Monte Carlo Simulation Experiments for Analysis
of HIV Vaccine Effects and Vaccine Trial Design
Daniel C. Barth-Jones (Wayne State University), Andrew L. Adams (NextHop Technologies) and James S. Koopman (University of Michigan)
The field of infectious disease epidemiology has increasingly adopted stochastic simulation technologies to simulate complex infectious disease transmission systems. Such simulations have both increased the scientific understanding of infectious disease transmission dynamics and served as important tools for evaluating epidemiologic study designs and statistical methods. This paper reports on a discrete-event simulation to analyze the recently developed Retrospective Partner Trials (RPT) HIV vaccine trial design. A specially designed simulation system, HIVSIM, was used to simulate data resulting from the RPT design vaccine trials. HIVSIM explicitly models complex HIV transmission dynamics (e.g., sexual partner mixing patterns and concurrent sexual partnerships) and vaccine trial design characteristics. Monte Carlo simulation analyses conducted with HIVSIM indicate that the RPT design is able to produce vaccine effect estimates with acceptably small bias, high precision and excellent statistical power under plausible HIV vaccine trial conditions. Additionally, the explicit simulation of HIV transmission dynamics permits investigations into the common, but unwarranted, statistical independence assumptions routinely used in the estimation of vaccine effects.
Simulation of the Drug Development Process: A Case
Study from the Pharmaceutical Industry
Russell W. Workman (Andersen Consulting)
This paper uses a case study from the pharmaceutical industry to show how simulation modeling can be applied to understanding large, highly-complex processes such as drug development. I conclude that simulation provides an enhanced resource planning capability compared with that provided by traditional spreadsheet analysis. This capability difference stems from the ability of a simulation to better reflect the variation which defines such complicated processes. The conditions which facilitate exploitation of this advantage include: capturing process information at the correct level of abstraction; successfully incorporating this information into a simulation model; and allowing easy user access to critical parameters via an intuitive interface.
Emerging Issues in Healthcare
Susan M. Sanchez (Naval Postgraduate School), David M. Ferrin (Andersen Consulting), Tom Ogazon (Jackson Memorial Hospital), José A. Sepúlveda (University of Central Florida) and Timothy J. Ward (Health Services Engineering)
Despite the size and importance of the health care industry, simulation is less prevalent in health care than in other fields such as manufacturing, logistics, and military applications. Yet simulation clearly has the potential to play a role in health care decision-making at many levels. The purpose of this panel is to discuss some of the issues that practioners must be aware of in order to tap the potential of simulation in the health care arena. The panelists have extensive experience in health care and the use of simulation in that environment. They have provided statements outlining several key issues for achieving success in current and future health care simulation projects. These will serve as the starting point for discussion at the conference.
Effective Uses of Business Process
Andrew Greasley (University of Derby)
This paper evaluates a number of tools for the redesign of processes through the use of two case studies based in the UK Police Service. There is a particular emphasis on the use of Business Process Simulation in conjunction with Activity Based Costing and Activity Based Budgeting within the context of a Business Process Reengineering approach. The use of a balanced scorecard and marking guide can be used to identify suitable processes for redesign. A process map enables a study of the relationship between the activities that form the process. The process map relates to the conceptual map in a simulation study. A Business Process Simulation based on the logic contained in a process map is demonstrated to enable a dynamic analysis of current process performance and proposed process design. To ensure that the results of the study are implemented the balanced scorecard can be used to set operational targets for performance measures. The current political and cultural context of the organisation should also be taken into account to ensure successful implementation.
Enterprise Simulation: Framework for a Strategic
Milind M. Datar (Concert, an AT&T and BT Global Venture)
The term Enterprise Simulation (ES) is gaining acceptance among simulation practitioners. It is coming to represent certain tangible attributes, and its benefits seem apparent in providing a top-down perspective in system analysis. It is envisioned as the next wave of simulation applications that may bring simulation to a higher ground of applicability in the business application arena. ES does so by promising to extend the benefits of simulation modeling and analysis as it is performed today. Linking singular instances of analytical efforts (simulation and otherwise) with limited scope in a network has the potential of delivering extraordinary value to decision-making at the corporate level. Moreover, advances in distributed simulation concepts and networking technology can provide the much needed push to ES by serving as enablers. This paper offers to explain the motivation behind ES, and explain its relevance to the business environment of large, complex organizations. A development framework is presented with technical and managerial issues in its implementation.
Applications of Business Process Simulation and Lean
Techniques in British Telecommunications PLC
Simon Dennis, Ben King, and Martin Hind (British Telecommunications PLC) and Stewart Robinson (The University of Warwick)
Business processes are increasingly key to the success of companies in the service industry. It is important that these processes are designed and maintained to deliver the most cost effective and efficient results. Simulation is being used in conjunction with other techniques to improve the performance of BT's processes, to evaluate new ideas and to plan operational resource requirements. The examples in this paper discuss firstly, the use of Value Stream Analysis (VSA) to identify inefficiencies in business processes and how simulation is used to evaluate improvement plans/develop future business scenarios derived from this, and secondly how simulation is used to match available resources to workloads.
Simulation Modelling: The Link between Change
Wendy Currie and Vlatka Hlupic (Brunel University)
Although change management panaceas have been widely discussed in the business and management literature for several decades, not many publications address the role of simulation modeling in supporting these panaceas. This paper investigates four management innovation and change programs: TQM, JIT, BPR and Process Innovation and discusses how simulation modeling could increase their effectiveness. These change management approaches are compared and contrasted and the applicability of simulation modeling to support the principles of these methods is investigated. It is argued that simulation could be viewed as a missing link between these approaches.
Creating a Paperless Municipal Court
John M. Petrakis (BIRG, Inc.) and Michael J. Engiles (CACI, Inc)
SIMPROCESSÒ was used to plan a phased migration from a traditional municipal court to a paperless court. The simulation model was also used to provide the financial justification, communication of the concept, and plan staffing for the revised operational procedures.
Venture Launch: Use of Simulation to Support Strategic
Gregory R. Clay (Andersen Consulting)
This paper describes how discrete-event simulation enhanced a traditional process design effort for a new media company in pre-launch mode. Because the company’s business model is new, and thus its critical operational processes are new, a need existed to not only design the new processes but also to determine at a high level the “goodness” of the proposed design. This high-level approach to simulation modeling can open new doors to simulation professionals accustomed to performing detailed simulation analyses. Benefits derived from use of the high-level simulation along with considerations for using high-level models in this rapidly changing environment are discussed.
Using Information Generated by the Discrete Event
Simulation to Evaluate Real Options in a Research and Development
Jerry Flatto and L. Leslie Gardner (University of Indianapolis)
This article examines how a discrete event simulation can be developed to evaluate the impact of real options on a research and development project. Previous work with real options has been primarily mathematically based and the approach was not transferable to actual projects. The results shown in this article indicate that simulation is a valid method to evaluate real options and that the real options do impact the net present value of a process.
The Merger of Discrete Event Simulation with Activity
Based Costing for Cost Estimation in Manufacturing
Ulrich von Beck and John W. Nowak (University of Illinois at Urbana-Champaign)
Activity based costing (ABC) has revolutionized product costing, planning, and forecasting in the last decade. It is based on a philosophy of estimation that: "it is better to be approximately right, than precisely wrong." The philosophy of discrete-event simulation modeling follows a similar tack, where statistical inference and the stochastic nature of processes are used to replicate the behavior of a physical system. In this work, ABC and discrete-event simulation are linked to provide an improved costing, planning, and forecasting tool. Numerous point cost estimates are generated by the ABC model, using driver values obtained from a discrete-event simulation of the process. The various cost estimates can be used to produce confidence interval estimates of both the physical system and underlying cost structure. Rather than having a single point estimate of a product's cost, it is now possible to produce the range of costs to be expected as process conditions vary. This improved cost estimate will support more informed operational and strategic decisions.
Electronic Workflow for Transaction-Based Work Cells
in a Financial Services Firm
David M. Ferrin, Martin J. Miller, and Gustavo Giron (Andersen Consulting)
In determining an electronic documentation system, a financial services firm utilized simulation to determine the necessary capital expenditure. Analysis included batching options, Service Level Agreements and Full Time Equivalent allocations and schedules. This information was then processed in transaction-based work cells which were redesigned using simulation. This paper discusses approach, benefits and lessons learned while developing multiple simulation models for an electronic documentation system.