Robert M. Saltzman

A Call Center Uses Simulation to Drive Strategic Change

A large, customer-focused software company relied on simulation modeling of its call center operations in launching a new fee-based technical-support program. Prior to launching this rapid program, call center managers were concerned about the difficulty of meeting a proposed guarantee to paying customers that they would wait less than one minute on hold. Managers also wanted to know how the new program would affect the service provided to their existing base of regular, nonpaying customers. We quickly developed an animated simulation model that addressed these concerns and gave the managers a good understanding for the impact on system performance of changes in the number of customers purchasing the rapid program and in the number of agents. The one-minute guarantee would be fairly easy to achieve, even if the percentage of callers in the rapid program became quite high. Managers also gained confidence that, with appropriate staffing levels, they could successfully implement the new program, which they soon did.

An animated simulation model for analyzing on-street parking issues

This paper describes an animated simulation model which was used to assess several strategies for improving urban on- street parking systems. Built in ARENA, the model tracks six key performance measures including the probability of finding a parking space, the time spent searching for a parking space, and the total amount of money put into parking meters. Sensitivity analyses performed with the model revealed that a drivers chances of finding a parking space increase at about the same rate as decreases in the mean actual parking time. The model was also used to assess the effects of various degrees of enforcement of the one-hour time limit on system performance. Finally, experiments were performed with the model to determine how newer meter technologies might affect parking revenues collected by city management. Specifically, when existing meters were replaced by resetting meters which zero out any time left after a car pulls out of a space, parking meter revenues rose by 23 %.

Optimal realignments of the teams in the National Football League

Abstract In the fall of 1995, the National Football League expanded for the first time since 1977, adding Carolina to the National Football Conference West division and Jacksonville to the American Football Conference Central division. However, this expansion, coupled with the departure of the Rams and the Raiders from Los Angeles, exacerbated an already inefficient alignment of the teams. This paper presents optimal realignments of the leagues thirty teams based on the goal of minimizing total intradivisional travel. These realignments are both fairer and considerably less expensive for the teams than the 1995 alignment.

Comparing skill-based routing call center simulations using C programming and arena models

This paper describes the modeling of a skill-based routing call center using two distinct simulation programming methods: the C language and the Arena software package. After reviewing the features of this type of call center, we describe the salient components of each method in modeling the call center. The paper concludes with a comparison of the pros and cons of using each simulation programming approach in this context.

Three proposals for improving short-term on-street parking

Abstract In most urban centers today, on-street metered parking systems allocate scarce short-term parking space in an unreliable and inequitable way. These systems are unreliable in the sense that a driver has a limited chance of finding a short-term parking space reasonably close to his or her destination. They are inequitable in that they fail to accurately serve equally well all segments of the parking public and the businesses these segments patronize. This paper describes three low-cost proposals designed to improve the availability of short-term on-street parking and tests them on a small scale with a simulation model.

A manager-friendly platform for simulation modeling and analysis of call center queueing systems

Call center operational performance is measured largely through queue times and customer abandonment rates, and thus managers have an acute need to understand how both management policies and stochastic factors affect these performance statistics. Simulation is an excellent vehicle for examining these relationships, but a lack of programming ability can be a barrier that prevents call center managers from making use of such models. To address this problem, we have developed a user-friendly Excel interface for a dynamic discrete event simulation model. The underlying model is a general queuing system for which analytical results are often unavailable, and the Excel interface enables managers to interactively specify a wide range of system parameters and analyze results, all without exposing them to the simulation models components. Based on input from call center operations managers, we have also been able to utilize this framework to ask, and answer, some important empirical questions.

An Exact Ceiling Point Algorithm for General Integer Linear Programming

Abstract : This report describes an exact algorithm for the pure, general integer linear programming problem (ILP). Common applications of this model occur in capital budgeting (project selection), resource allocation and fixed- charge (plant location) problems. The central theme of our algorithm is to enumerate a subset of all solutions called feasible 1-ceiling points. A feasible 1-ceiling point may be thought of as an integer solution lying on or near the boundary of the feasible region for the LP-relaxation associated with (ILP). Precise definitions of 1-ceiling points and the role they play in an integer linear program are presented in a recent report by the authors. One key theorem therein demonstrates that all optimal solutions for an (ILP) whose feasible region is non-empty and bounded are feasible 1-ceiling points. Consequently, such a problem may be solved by enumerating just its feasible 1-ceiling points. Our approach is to implicitly enumerate 1-ceiling points with respect to one constraint at a time while simultaneously considering feasibility. Computational results from applying this incumbent-improving Exact Ceiling Point Algorithm to 48 test problems taken from the literature indicate that this enumeration scheme may hold potential as a practical approach for solving problems with certain types of structure.

Using Simulation to Model Improvements in Pediatric Bed Placement in an Acute Care Hospital

OBJECTIVE The objective of this project was to use an interdisciplinary approach to analyze strategies through simulation technology for improving patient flow in a pediatric hospital. BACKGROUND Various statistics have been offered on the number of children admitted annually to hospitals. For administrators, particularly in smaller systems, the financial burden of equipping and staffing pediatric units often outweighs the moral desire to maintain a pediatric unit as a viable option for patients and pediatricians. METHODS Discrete event simulation was used to model current operations of a pediatric unit. Cost analysis was conducted using simulation reflecting various percentages of patients being referred to a discharge holding area (DHA) upon discharge and of the use of all private rooms. RESULTS Both DHA and private rooms resulted in increased patient volumes. CONCLUSIONS Administrators should consider the use of a DHA and/or private rooms to ease the census strains of pediatric units and the resultant revenue of this service.

Perspectives on teaching simulation in a college of business

In this paper, we explore the challenges and opportunities we face teaching computer simulation at a business school. While our students tend not to be as technically savvy as most engineering students, at times limiting the technical complexity of what we can cover in our courses, we are able to use simulation as a tool to analyze and discuss business problems in-depth. We explore the differences both between business and non-business simulation courses, as well as those between our graduate and undergraduate courses.

Simulating student flow through a college of business for policy and structural change analysis

Under the pressure of sharp budget cuts and external demands for better performance, public institutions of higher education must examine how they can facilitate student graduation even as institutional resources diminish. This paper describes a computer model simulating the movement of undergraduates through a large, public college of business. The model allows changes in curriculum policy, prerequisite structure, and staffing capacity to be tested prior to implementation. Outcome measures focus primarily on the expected time to degree of two types of students who enter the university, first-time freshmen and upper division transfers, along with their respective 6-year and 4-year graduation rates. The validated model is used to experiment with both actual and potential scenarios facing the college and gauge their possible impact.