Motivation
The simulation of processes (waiting lines, factories, supply chains, and so on) is one of the conceptually simplest and most often applied techniques in Operations Management and Management Science, yet it has not been widely taught to business students. A key reason for this is that performing process simulation requires the use of software, and the software that is available tends to be complex and expensive. Even the more graphics-based packages, although often beautifully designed, frequently have an enormous number of features that place an unnecessary burden on students (and instructors) in classes that are not devoted to simulation.
SimQuick is an Excel-based software package for process simulation that is easy to learn, easy to use, and freely distributed. (Its key features can be learned in an hour or two of class time or independent reading.) It is an ordinary Excel file with some hidden macros and should run immediately on any modern personal or networked computer that runs Excel, either a PC or an Apple computer; it is not an “add-in” and requires no “installation.” Hence, users of Excel will already be familiar with much of the interface, and the results are already in the spreadsheet, ready for analysis.
SimQuick is aimed primarily at business students and managers who want to quickly learn the basics of process simulation and be able to quickly analyze and improve real-world processes. SimQuick is flexible in its modeling capability; that is, it is not a “hardwired” set of examples; it requires true modeling. The user can combine the basic building blocks of SimQuick in a huge variety of ways. Hence, SimQuick can serve well as an introduction to both the notion of building quantitative models as well as the important field of simulation. Since the first version of SimQuick was released in 2001, it has been used in industry as well as in the classroom; its original design and subsequent updates have been informed by comments from users in both domains.
This (inexpensive) booklet accompanies SimQuick. It presents the basics of process simulation by having the reader construct, run, and analyze simulations of realistic processes using SimQuick. An emphasis has been placed on explaining precisely how the various building blocks of SimQuick work. Chapter 1 contains a brief introduction to process simulation and the concepts underlying SimQuick. The next four chapters contain a variety of examples of process simulation. These examples are organized as follows: waiting lines (Chapter 2), inventory in supply chains (Chapter 3), manufacturing (Chapter 4), and project management (Chapter 5). Each example is followed by an exercise. All of the examples and exercises have been designed with business students and managers in mind.
In addition to presenting the basics of process simulation, this booklet introduces a number of key concepts from the analysis of processes: service level, cycle (or waiting) time, throughput, bottleneck, batch size, setup, priority rule, and so on. The booklet also introduces some key trade-offs from the analysis of processes: number of servers vs. service level, inventory level vs. service level, working time variability vs. throughput, batch size vs. service level, and so on. These notions are presented through computer models that the reader constructs and experiments with using SimQuick.
How to use the booklet
The booklet is self-contained; that is, all technical terms involving processes or operations are defined. (The reader is assumed to have a rudimentary understanding of how to use Excel on the level of knowing how to save files and how to enter information into cells.) The chapters are organized around typical topics in Operations Management and Management Science courses so that this booklet can easily be used in these types of courses.
The reader should first read Chapter 1 (which contains a conceptual explanation of process simulation and SimQuick) and Section 1 of Chapter 2 (which contains a step-by-step explanation of how to use SimQuick by completely working through a simple example). After this, the reader has a lot of freedom (with some Examples recommended as prerequisites in a few spots).
Chapters 2 through 5 consist of examples of processes that can be modeled using SimQuick. When needed, an example discusses how to build the SimQuick model. Each example is followed by an exercise.
A quick treatment of process simulation could consist of working through Example/Exercise 1 for waiting lines and Example/Exercise 19 for manufacturing. With just this material, many real-world processes can be easily modeled and studied. Adding Example/Exercise 5 with Decision Points would allow the modeling of many more types of processes. A reading of Examples 8, 9, and 10 would introduce the notion of Changing Distributions and further increase the variety of real-world processes that can be modeled. Adding Examples/Exercises 13 and 14 would provide a quick introduction to the modeling of inventory in supply chains and adding Example/Exercise 26 would serve as an introduction to the incorporation of uncertainty into project management models.
The booklet contains five appendices. Appendix 1 contains a list of the basic steps in conducting a simulation project. Appendix 2 contains tips on how to enhance SimQuick by using some of the features built into Excel. A tool with wide applicability, called Scenarios, is discussed in Appendix 3, where references are made to several Examples/Exercises from the text. Appendix 4 describes how to use a feature of SimQuick called Custom Schedules. Appendix 5 contains a succinct description of all the features of SimQuick and can be used for reference. Hence, the features of SimQuick are presented in two ways: through examples and in a reference manual.
Solutions to exercises: Instructors can obtain solutions to every exercise. To obtain solutions, an instructor should send a request to the author (Hartvigsen.1@nd.edu) with a copy of their course syllabus and a link to their webpage at their educational institution.
Web site: Refer to SimQuick.net for additional information on SimQuick, this booklet, and technical support.
Over the past 15 years, I have used SimQuick in the classroom with executive MBAs, full-time MBAs, and undergraduate business students. After a one-hour introduction in class (basically, covering Section 1 of Chapter 2), the students successfully solve a variety of modeling problems with little help. This introduction has also served as a launching pad for term projects, whereby students identify and analyze real-world processes of their choice.