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The article presents abstracts of contributed papers submitted for presentation at the Chicago Meeting. The paper "Computer Simulation in a Missile Operational Cycle," by Robert T. Morrison explains a model of a hypothetical weapon system is analyzed by simulation techniques using a digital computer. All the important parameters affecting the model are identified and values selected. Random numbers selected by the computer are used to determine the occurrence of missile and GSE malfunctions according to the failure rates established and also to determine the repair times for the missiles and GSE if malfunctions occur. Another paper "A Measure of Effectiveness for Weapon-System Evaluation," by Robert T. Morrison explains a concept for a measure of effectiveness is developed for evaluating and judging weapon-system design and operation The proposed measure of effectiveness considers the most important factors in any complex system-maximum performance and reliability with minimum cost and time This paper shows how the measure of effectiveness is valuable for system analysis in judging between alternative proposed systems in preliminary design and measuring and evaluating the selected system progress from prototype design through final system operation and maintenance.

In this paper I argue that a paper by Castro and Weingarten entitled "Toward Experimental Economics" is both misleading and incomplete. First, the literature in economics abounds with articles on experimental economics. Second, the authors' survey of the literature in experimental economics omits some of the most important contributions in this field. Third, the authors completely ignore an important new field of experimental economics--namely, computer simulation experiments with models of economic systems. My paper contains an extensive survey of the literature on real-world experiments in economics as well as computer simulation experiments. [ABSTRACT FROM AUTHOR]

The explanation of organizational structure has always been an important issue to administrative theorists. This paper investigates the structure of manufacturing operations and therefore starts from the premise that technological factors are most crucial. One current approach to structure and technology, comparative analysis, has studied the overall context but at a highly aggregative level. The "constituent" approach, on the other hand, has investigated intraorganizational relationships but at the expense of empirically verifiable theory. We develop a heuristic computer model capable of testing existing constituent theories. The model uses work flow data as technological inputs and produces a structural configuration as output. It employs administrative rules (based on Thompson's propositions for structuring the technical core) to convert inputs into outputs. The inputs, outputs, and rules are formally represented using list processing concepts. Operationalizing the formal concepts has been satisfactorily explored in a pilot study of a small manufacturing firm. Testing existing constituent theory is just the initial phase of this project. It is possible to develop new structural theory for the technical core and the rest of the organization, and to engage in a form of comparative analysis to judge the effects of varying contexts. Moreover, the fact that a structural configuration is produced implies utility in the area of design. [ABSTRACT FROM AUTHOR]

Copyright of INFOR is the property of Taylor & Francis Ltd and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This paper describes some key defining characteristics of s special class of information systems known as Management Myth-Information Systems (MMIS) or story-telling information systems. MMIS are information systems [26] which present information to a decision-maker by means of stories. In an MMIS, a scientific datum by itself is not information. In an MMIS, information is information if and only if it is tied to an appropriate story or myth that has meaning to the individual who needs the information, the organization in which he is located, and the type of problem that he faces. This defines the key variables underlying an MMIS. As such, the study of the critical literature dealing with the nature and function of mythology becomes central to the design of MMIS. One of the key purposes of this paper is to suggest how the literature of mythology and the phenomenon of story-telling can be used in the design of MMIS it not for information systems in general. An experiment dealing with some central features of MMIS is described. The experiment involved playing a series of games under the twin conditions of (1) uncertainty and (2) dialectical advice. Experimental subjects were exposed to the advice of two radically opposing "experts of the game" who were designed to present two radically opposing views ("stories") of the game situation. Finally, a program of research on MMIS is proposed. [ABSTRACT FROM AUTHOR]

This paper presents results of research into computer simulation of a mixed-model assembly line. The problem to be solved is described and the mathematical model of the line is presented. Algorithms that provide acceptable sequences of product models in various conditions are given, and results of simulator experiments are analysed and discussed. In the final section of the paper conclusions are drawn from the results of the work, and the general usefulness of simulation for assembly work is considered. [ABSTRACT FROM AUTHOR]

This article presents a list of books related to operations research. Names of these books include "Computer Simulation of Competitive Market Response," by Arnold E. Amstutz; "Production Control: A Quantitative Approach," by John E. Biegel; "Designing Social Service Systems," by Jack C. Bloedorn, Elizabeth B. Maclatchie and J.M. Wedemeyer; "Network Analysis for Planning and Scheduling," by Albert Battersby; "Optimization," by A.O. Converse; "An Introduction to Probability, Decision, and Interference," by Irving H. Lavalle.

This paper develops a Bayesian analysis of the scale and shape parameters in the Weibull distribution and the corresponding reliability function with respect to the usual life-testing procedures. For the scale parameter θ, Bayesian estimates of θ and reliability are obtained for the uniform, exponential, and inverted gamma prior probability densities. BHATTACHARYA'S results [J. Am. Stat. Assn. 62, 48–62(1967)] for the one-parameter exponential life-testing distribution are reduced to a special case of these rewards. The paper develops a fully Bayesian analysis of both the scale .and shape parameters θ and ξ by independent prior distributions; since in the latter case, analytical tractability is not possible, Bayesian estimates are obtained through a conjunction of a Monte Carlo simulation and numerical-integration techniques. In both cases, the paper carries out a computer simulation and makes a comparison between the Bayesian and the corresponding minimum-variance unbiased, or maximum likelihood, estimates. As expected, the Bayesian estimates are superior. [ABSTRACT FROM AUTHOR]

The paper evaluates and compares classes of multi-item inventory problems where joint order of several items may save a part of the setup cost. A cost ratio and simple decision rule are determined for joint versus individual orders in specified cases. The comparisons call for the necessity of a new policy for reorder point-triggered random output multi-item systems. This policy, "the random joint order policy," operates through the determination of a reorder range within which several items can be ordered. The existence of an optimum reorder range is proved, and a computational technique is demonstrated with the help of a machine-interference type queueing model. Under favorable conditions the results exhibited on the diagram of optimum reorder ranges are generally applicable. The random joint order policy model is especially suitable for computer controlled inventory systems. [ABSTRACT FROM AUTHOR]

This paper explores methods for scheduling preventive maintenance by means of mathematical programming. Five integer linear programming models are posed, each based on a different optimality criterion dealing with manpower smoothing. By means of two hypothetical examples the models are tested for their computational properties. In addition to describing the experimental results of applying integer linear programming techniques to this class of problems, the paper also illustrates how effectively rounded linear programming solutions can be used as approximations to optimal solutions. [ABSTRACT FROM AUTHOR]

The article presents comments of the author on a paper by Melvin N. Greenball, "Evaluation of the Usefulness to Investors of Different Accounting Estimators of Earnings: A Simulation Approach," evaluating the usefulness of different accounting estimators of earnings to investors. The author explains that the stated objective of Greenball's research is to test the hypothesis that certain accounting methods generate earnings estimates which are useful to outside investors than those generated by other accounting methods.

This is an interim report on a comparative study of paced and unpaced worker performance. A number of pilot experiments are described involving simple physical and mental, including inspection, tasks paced by conveyor and other systems. Tentative findings are given, relating to output, quality of performance, distributions of operation times and ratios of constituent motion element times. Reference is made to preliminary work on computer simulation of paced systems. This Paper describes recent and current research at Birmingham which aims at contributing to the understanding and hence to the solving of these problems by way of comparative studies of the characteristics of paced and unpaced performance of workers engaged on highly repetitive tasks. [ABSTRACT FROM AUTHOR]

This paper considers fluid analogues for the standard linear programming problem and for a separable nonlinear programming problem. In the former case the usual duality results are demonstrated using the principle of minimum potential energy. In addition by examining the dynamics of the system a new method, referred to as the R-method, is derived for solving linear programmes, although it is not demonstrated that this has any computational advantages over the standard simplex method, except that degeneracy causes no problems. In the nonlinear case the weak Lagrangian principle is derived. The purpose of the paper is to demonstrate that analogue methods, while being impracticable as a physical method of solving optimisation problems, may give some insight into computational algorithms via dual energy concepts and/or dynamic behaviour. [ABSTRACT FROM AUTHOR]

This paper presents a method for estimating the variances of sample performance measures in queueing simulations, for removing the bias in these sample measures due to initial conditions and for deriving approximating confidence intervals for the true performance measures. It also describes how a variance reduction can be achieved using the method when comparing performance measures for two queue disciplines. The approach requires only that every time the system passes through the empty and idle condition future behavior is independent of past behavior. [ABSTRACT FROM AUTHOR]

This paper describes a computer simulation of insurer financial behavior, based upon a risk-theoretic model previously reported in the Journal The simulation can be used to study the impact of a great variety of managerial policy combinations--in a great variety of circumstances-upon specified financial results. This discussion is limited to a study of the consequences of complying with the one-to-one solvency rule as opposed to adhering to a .001 ruin criterion. In four of the five eases studied the .001 criterion yields distinctly different consequences for policyowners, shareholders or both. The fifth case permits an indefinitely large premium volume with comparable results for both criteria. More generally, simulation emerges as a potentially useful tool for refining both the theoretic and empirical aspects of scientific study. [ABSTRACT FROM AUTHOR]

This paper is concerned with the question whether workers gain or lose on their taxes for social security (OASI). Tax-benefit ratio (T/B) and rate of return (HR) are the two measures by which to determine how they fare under the system. T/B and RR are affected by earnings level of the worker, time period of paying taxes and drawing benefits, whether the employer's tax is shifted to the worker, types of benefits received, rates of interest and of price inflation. A computer simulation program is utilized to produce T/B and HR for 1974 retirees and 1974 entrants (age 22 and age 18). T/B for 1974 retirees range from .05 to .46; their RR vary between 6.1 percent and 16.9 percent. T/B for 22 year-old 1974 entrants are from .22 to 1.57; their RR, from 1.4 percent to 8.5 percent. T/B for 18 year-old 1974 entrants are from .25 to 1.86; their RR, from 1.1 percent to 7.7 percent. [ABSTRACT FROM AUTHOR]

Copyright of INFOR is the property of Taylor & Francis Ltd and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This paper presents a case study on the use of mathematical-computer models in developing operating policies for a university-health-service outpatient clinic. Based on results predicted by the models, actual policy changes were made in the system; the paper compares the subsequent real-world results with those predicted by the models. The comparison demonstrated the validity of the models, and significant improvements were realized in the changed system. An analysis of daily arrival patterns was used to schedule more appointment patients during periods of low walk-in demand in order to smooth the overall daily arrivals. A Monte Carlo simulation model showed the effects of alternative decision rules for scheduling appointment periods during the day to increase patient throughput and physician utilization. [ABSTRACT FROM AUTHOR]

A policy simulative model with the main purpose of simulating the effects of alternative policy moves and obtaining an accurate read-cut of resulting urban-suburban conditions is the focus of this paper. The model deals with the movement of various population groups and the resulting effects on some very broad indicators of city-suburban life, rather than with particular topics like transportation, land use and the like. The level of abstraction is thus intermediate and is directed at providing practical policy suggestions for a particular city-Newark-for which the model is calibrated. The model, however, is general enough in nature so that it can be applied lo other urban-suburban complexes and therefore the policy suggestions made on a fairly broad basis. The outputs of the model are graphically represented to show the results of alternative policies which then may be compared. As a side benefit the inputs to the model can also serve as a "social report" on the present status of an area. Policy questions to be answered by the model include: Should a city budget be directed somewhat differently? Should a city ask the state or federal government for funding and for how much .' What may be expected from imposing a city sales tax. weighing the revenue benefit against costs of lost sales or citizens? And last, would the federal government not be better off by simply giving money to the poor directly instead of to cities? [ABSTRACT FROM AUTHOR]

Within the past decade there has been a steadily increasing use by operations researchers of computer simulation techniques in studying complex industrial and military systems. Economists are now beginning to recognize that similar techniques may be helpful in analyzing complex economic systems. The purpose of this paper is to consider some reasons why simulation may be a useful addition to the professional economists bag of tools, especially in research on the theory of the firm. Since relatively little substantive work in simulating microeconomic models has been published to date, the assessment of the role that this new methodology may play in developing the theory of the firm must be based on programmatic considerations rather than on achieved results. The term computer model is used to denote a special kind of formal mathematical model, namely, a model which is not intended to be solved analytically but rather to be simulated on an electronic computer. Simulating a computer model consists in using a digital or analog computer to trace numerically or graphically the time paths of all endogenous variables generated by the model.

This paper reports a study which developed and empirically tested a simulation model of the process by which zoning ordinances are altered to adapt to the changing needs and conditions of a city. The perceived decision rules of the participants are reported in the form of flow charts which utilize language similar to that used by the participants. The body of the paper indicates methods which were used to translate these judgmental rules into a form suitable for a computer. The model was tested by allowing the computer to decide the one hundred twenty-five proposed changes in the zoning map of the City of Pittsburgh during the period 1963 to 1965 inclusive. The results were good in the sense that the computer model decided most of the cases in the same way as did the human participants. Additional tests and managerial implications are also discussed. [ABSTRACT FROM AUTHOR]

This paper describes the use of multiple ranking procedures to analyze data generated from computer simulation experiments with models of management systems. After outlining the rationale for the use of multiple ranking procedures with computer simulation experiments and defining some basic terminology, we examine several specific multiple ranking procedures. Careful attention is given to the assumptions underlying the different multiple ranking procedures and the extent to which these assumptions are satisfied by the data generated by simulation experiments. An example model is included to illustrate the applicability of multiple ranking procedures to simulation experiments in management science. [ABSTRACT FROM AUTHOR]

This paper describes a model for a computer stimulation designed to analyze and forecast the financial posture of a computer leasing company as a subsidiary to a large corporation. The simulation considers the rate of market growth, the year of the introduction of fourth generation hardware and the year that the computer manufacturers act to impede the growth of the leasing industry, as random variables. Other assumptions are input as equations or constants. Financial analyses are performed during a five year simulation period. The means and the 10% and 90% quantile range for several key financial indicators are determined and plotted. [ABSTRACT FROM AUTHOR]

This paper starts with a brief summary of Harry Markowitz's portfolio selection model and proceeds to reformulate it within the framework of modern statistical decision theory. The future returns from securities are viewed as a function of the unknown state of nature. The investor has certain a priori probabilities for the different states of nature, which probabilities he later modifies in the light of new experimental information. Following the Bayesian strategy, the investor chooses that portfolio of securities which maximizes the weighted average of payoffs, using as weights the a posteriori probabilities of the states of nature. A computer program, based on the critical line method, is used to solve a simple illustrative problem. [ABSTRACT FROM AUTHOR]

This paper describes the use of simulation techniques at SDC in the analysis of time-sharing system operation. The purpose and goals of this research effort are briefly outlined and some comments on the advantages and disadvantages of direct simulation for this type of work are given. The existing simulator models are described in terms of inputs, general flow, and outputs; and the results of initial investigations with these models are given. Work currently in progress is discussed, and some related problems that may possibly be studied in the future by similar methods are noted. [ABSTRACT FROM AUTHOR]

In this paper we utilize traditional microeconomic theory and elementary queuing theory to develop a computer simulation model of a single-product, multi-process firm. One of our objectives is to demonstrate that the body of economic theory known as the "theory of the firm" may be used to provide a convenient frame of reference in applying some of the more recently developed analytical tools of operations research and computer technology to the analysis of the behavior of the firm. The static equilibrium model of the firm presented in Value and Capital by J. R. Hicks is taken as a point of departure in constructing a simulation model in which (1) the time interval between the arrival of orders at the firm is a stochastic variate with a known probability distribution, (2) each order which the firm receives must pass through n processes before it is transformed into a single unit of output, and (3) the time interval which an order spends at the jth process (j = 1, ..., n) is a stochastic variate with a known probability distribution. [ABSTRACT FROM AUTHOR]

In the SANS [1, 2] system, which attempts to reduce alphabetical and numerical files to a single file, problems of overflow occur when new members fall between two existing members with consecutive numbers. A method is given for determining the probability distributions of overflows in a cell of size 2k, and the mean value and variance of these distributions as functions of the growth of the system. In this paper we use some of the results of another paper on a related problem [4] to formulate the problem and obtain a solution. The mathematical treatment outlined can be extended to the calculation of other important parameters, including the expected number of entries which will be out-of-order within a group of areas, and the probability that the last overflow area will itself have an overflow. [ABSTRACT FROM AUTHOR]

The article presents an elaboration of the papers of Herbert A. Simon on "Computer Simulation of Human Thinking and Problem Solving" and "An Information Processing Theory of Intellectual Development." The papers explore whether the inclusion in a computer simulation of the initial variations in state leads to uses of materials at various degrees of cognitive development. Simon suggests that the building of an information-processing system which mimics child behavior at a specific stage of development provides a "theory of the child" at that stage.

This paper illustrates how computer simulation techniques can be used to simulate information systems. A computer program for a small system was written in GPSS III (a special simulation language) and run in an IBM-7090 Computer. The results obtained and the types of conclusions drawn are briefly discussed. [ABSTRACT FROM AUTHOR]

A three dimensional variable dimensioned computer model of a man has been developed which can be used as a conversational mode design tool. This paper illustrates the use of this model for equipment design, in particular to determine whether controls can be reached and whether equipment dimensions are suitable to match different members of the population. The equipment may be described either by special purpose or general purpose environmental modelling systems. The modules of the general purpose system may be assembled into a model of the equipment and then evaluated by taking the operator, represented by the computer man, through a typical work sequence. If the dimensions or positions of the modules are unsatisfactory they may be altered conversationally and the new design retested. [ABSTRACT FROM AUTHOR]

The paper describes work done by the White Fish Authority's Industrial Development Unit to exploit a method of transferring fish at sea between a fleet of trawlers. Both the operations research study and subsequent implementation are described. [ABSTRACT FROM AUTHOR]

The paper illustrates the desirability and feasibility of the computer simulation technique in socio-psychological research. A computer simulation model of a five-man industrial work group is constructed. After the model has successfully passed a two stage validation procedure, an experimentation phase is conducted. In a 2 × 3 replicated factorial experiment, five years of simulated weekly data is used to test several hypotheses which relate the independent variables—supervisory style and worker interpersonal orientation—to productivity, worker job satisfaction and group cohesiveness. The hypotheses were derived from the findings of prior short-lived laboratory and field research. The study indicates that the computer simulation approach is a valuable adjunct to the classical organizational research techniques. [ABSTRACT FROM AUTHOR]

A hierarchical queuing network is a layered network of queues in which all arrivals receive initial service from a primary server, and some customers receive additional service jointly from a primary and a secondary server. This paper considers the simplest such network, involving two levels and a single secondary server who functions as a consultant to several primary servers and always works in conjunction with the primary server who refers the customer to him. An approximate analysis of this hierarchical queuing network is carried out for three operating disciplines governing the consultation process. The analytical results compare favorably with the results of computer simulations and are therefore used to explore several important issues in the design of such networks. Hierarchical queues are common in public-service systems, including new medical-care systems known as "telemedicine." [ABSTRACT FROM AUTHOR]

This paper describes the use of computer simulation of the diagnostic process - a method of training learning disabilities specialists. Prospective learning disabilities specialists gained experience in the diagnostic process via operational computer simulations. The simulated settings provided a way to bridge the gap between courses in theory and the actual clinical experience. [ABSTRACT FROM AUTHOR]

This paper presents the motivation for the construction of a digital computer simulation of the American military's strategic airlift system, the author's analysis of that system preparatory to the simulation design, and the currently anticipated application of the model to studies of strategic mobility. Emphasis is placed on the estimation of the airlift productivity function for its subsequent utilization in appropriate strategic mobility models employed by the Joint Chiefs of Staff and by the Office of the Assistant Secretary of Defense (Systems Analysis). Those variables suspected of being primary contributors to gains in marginal airlift productivity are delineated in a description of the modules constituting the model. Finally, a sketch of an hypothetical experimental design, permitting the systems analyst to specify sequentially model iterations so as to obtain valid statistical estimates of desired marginal productivities, serves as a conclusion to the paper. [ABSTRACT FROM AUTHOR]

Using a tutorial and expository approach, this paper assesses the performance of some simple, idealized input, output, and compute overlap configurations. Equations are given for one- and two-channel configurations that have one, two, and three partitions of main storage. The objectives of the paper are to gain insight into bounds on system throughput performance and to give equations useful for checking computer simulation. [ABSTRACT FROM AUTHOR]

Experimental design considerations have been virtually ignored by economists who have conducted computer simulation experiments with models of economic systems. The objective of this paper is to spell out in detail the relationship between existing experimental design techniques and techniques of data analysis and the design of simulation experiments with economic systems. We begin by defining the problem of experimental design as applied to computer simulation experiments. With the aid of an example model, we explore several techniques of data analysis and a number of specific experimental design problems. Although this paper is oriented towards the design of computer simulation experiments in economics, the techniques which are discussed are of a general nature and should be applicable to the design of simulation experiments in other disciplines. [ABSTRACT FROM AUTHOR]

This paper describes a comprehensive simulation modeling approach to the problem of locating warehousing facilities in a fashion that minimizes the cost associated with operating a multi-product, multi-source, multi-destination distribution system. The digital simulation model presented in the study is derived within an "industrial dynamics" framework, utilizes input from an existing management information system, and employs a number of relatively simple heuristic procedures to analyze various alternative warehousing networks. Simulation results, in terms of the distribution costs associated with various warehouse locations, are presented for cases involving the effect of provision of a 100% service level, the effect of constraining product availability and/or inventory capacities at various warehouses, and the effect of deleting various warehouses from the existing warehouse network. [ABSTRACT FROM AUTHOR]

When computer simulation is being used to investigate a problem, any attempt at obtaining an optimum solution usually involves a search of the relevant factor space. Became a number of search techniques are available, it is desirable to bye some criteria for selecting the technique to be used in a specific simulation situation. However, no mathematical basis exists for an evaluation of these techniques relative to characteristics, that may vary from simulation to simulation. Thus, it is necessary to perform empirical studies ia order to obtain the required information. This paper discusses the homework and results of an empirical evaluation of the performance of name search techniques. It wag based on applying the techniques to various multidimensional situations that were constructed so that the true optimum vas known, providing comparison of the performance of each technique with the true optimum, as well as with the performance of other techniques. Each of the search techniques was evaluated for a variety of simulation characteristics in the situation where the available number of computer runs was relatively small compared with the number of factors being examined. [ABSTRACT FROM AUTHOR]

This paper describes a case study of selected inventory accounts maintained by a large manufacturer of rocket engines. It was hypothesized that a significant improvement in average inventory levels, number of purchase orders, and number of stockouts could be obtained by augmenting existing methods of inventory management with certain OR based techniques. These techniques included exponential smoothing of demand forecasts and statistical determination of optimum safety stock levels. Computerized simulation was used to determine: (1) the most effective parameter (alpha) values for use in the exponential smoothing formulas, (2) an estimate of the potential dollar savings obtainable if the proposed methods were implemented, and (3) a means by which these methods could be implemented. A simulation model was developed for two particular inventory accounts, its correspondence with the real world was tested, and the alpha values and anticipated dollar values were determined. Additionally, a set of curves were developed for use by inventory management to assist in determining an optimized policy for varying values of purchase order cost, inventory carrying rate, and cost of stockouts. [ABSTRACT FROM AUTHOR]

This paper discusses the Air-Battle Model that, with its supporting computer programs, is a device for simulating a large-scale two-sided global war on a high-speed digital computer. The three parts, the Plan Converter, the Air-Battle Model, and the Output Programs, of the Air-Battle-Model System are discussed. Some applications of the Air-Battle Model are shown and the technique of using gross summary measures to obtain a feel for some key conclusions and using detailed studies to determine why some conclusions resulted is demonstrated. [ABSTRACT FROM AUTHOR]

This paper describes two statistics which may be used to test hypotheses about the association between two variables when observations are cross-classified in a contingency table. The two sets of null hypotheses are described and differences between the sets of alternate hypotheses covered by each statistic are outlined. Responses from populations with underlying bivariate linear and monotonic association were computer-simulated to compare the relative control over Type I error and power for each statistic. Sample sizes of 50 and 100 and contingency tables of size 3 x 3 and 4 x 4 were employed in the simulation. For the selected parameter combinations and distribution characteristics, S yielded a proportion of Type I errors which was generally closer to the nominal a than did x² Further, tests based on S rejected proportionally more false α than did x² for nearly all parameter combinations. General experimental situations are described in which tests based on S would be preferred over those based on x². An example of such a situation is included. [ABSTRACT FROM AUTHOR]

Experimental designs have found widespread application in the biological and physical sciences. The purpose in using these designs is not only that they are economical in terms of the number of experimental trials required, but more importantly, they provide a structure for the investigator's learning process. Experimental designs are available for (1) investigating the relationship of the response to the factors in order to determine the underlying mechanisms governing the process under study and (2) finding the combination of factor levels at which the response variable is optimized. Since a computer simulation experiment is indeed an experiment, it follows that one should give careful attention to experimental design questions prior to conducting a simulation experiment. Within the context of two simulation experiments with an inventory model, this paper discusses factorial, fractional factorial, rotatable, and response surface designs. We conclude by outlining a number of possible pitfalls and contingencies. [ABSTRACT FROM AUTHOR]

The problem of validating computer simulation models of industrial systems has received only limited attention in the management science literature. The purpose of this paper is to consider the problem of validating computer models in the light of contemporary thought in the fields of philosophy of science, economic theory, and statistics. In order to achieve this goal we have attempted to gather together and present some of the ideas of scientific philosophers, economists, statisticians, and practitioners in the field of simulation which are relevant to the problem of verifying simulation models. We have paid particular attention to the writings of economists who have been concerned with testing the validity of economic models. Among the questions which we shall consider are included: What does it mean to verify a computer model of an industrial system? Are there any differences between the verification of computer models and the verification of other types of models? If so, what are some of these differences? Also considered are a number of measures and techniques for testing the "goodness of fit" of time series generated by computer models to observed historical series. [ABSTRACT FROM AUTHOR]

Considerable attention in recent years has been given to the computer simulation of human thought processes in problem solving. This paper describes the computer simulation of the decision processes of a psychologist dealing with the ill-structured problem of analyzing psychological test scores and other data concerning individuals being considered for various types of clerical and clerical-administrative positions. The computer model was designed to output, as did the psychologist in his decision making, both: (1) numerous interpretive comments about each applicant, and (2) a specific recommendation as to whether the individual should be employed. The methodology and results of this research are described, and the possibility of utilizing computerized models of this type as an aid in personnel selection is suggested. [ABSTRACT FROM AUTHOR]

The SIMSCRIPT programming system is especially designed to facilitate the writing of simulation programs. Digital simulations generally consist of a numerical description of "status", which is modified at various points in simulated time called "events". SIMSCRIPT simulations consist primarily of a collection of "event routines" written by the user describing how different kinds of events in a particular simulated world affect current status and cause future events. Status is described in terms of various "entities", "attributes", and "sets" as specified by the user. [ABSTRACT FROM AUTHOR]

An inventory model is considered where every N periods an order is placed for an amount which brings the sum of stock-on-hand plus on-order up to some level S. The model treats a single item for which there is random demand. Demands that arrive when there is no positive inventory on hand are back-ordered. Leadtime is treated as random and the receipts of orders are allowed to cross in time. Values N(*) and S(*) which minimize steady state expected costs per unit time cannot be found. In this paper approximations, N[sub 0] and S[sub 0] are found. These are determined by minimizing an expected cost per unit time which has been maximized over all distributions of stock deficit with a given mean and variance. The method is applicable even when the functional form of the distribution of demand is not known. Computer simulations are used to indicate the values of the input parameters for which the expected costs per unit time associated with N[sub 0] and S[sub 0] are close to the similar quantities for N(*) and S(*). [ABSTRACT FROM AUTHOR]

This paper describes an improved method for investment decision making. The method, which is called the stochastic decision tree method, is particularly applicable to investments characterized by high uncertainty and requiring a sequence of related decisions to be made over a period of time. The stochastic decision tree method builds on concepts used in the risk analysis method and the decision tree method of analyzing investments. It permits the use of subjective probability estimates or empirical frequency distributions for some or all factors affecting the decision. This application makes it practicable to evaluate all or nearly all feasible combinations of decisions in the decision tree, taking account of both expected value of return and aversion to risk, thus arriving at an optimal or near optimal set of decisions. Sensitivity analysis of the model can highlight factors that are critical because of high leverage on the measure of performance, or high uncertainty, or both. The method can be applied relatively easily to a wide variety of investment situations, and is ideally suited for computer simulation. [ABSTRACT FROM AUTHOR]

The widespread use of simulation in the design and analysis of complex systems has received a great impetus in the past few years with the advent of various general simulation languages. Simulation models of a wide variety of physical situations can now be developed with these languages. This paper summarizes and compares various characteristics of five major general simulation languages. The historical background from which these languages developed is discussed first. Predictions are also made on the future development of general simulation languages. [ABSTRACT FROM AUTHOR]