Trading places: An experimental comparison of reallocation mechanisms for priority queuing

In a laboratory experiment, we compare two auction mechanisms that are designed to improve a queue's efficiency by allowing customers to trade places. In the server‐initiated auction, the server, when idle, sells the right to be served next to the highest bidding customer in the queue and distributes the proceeds among the remaining customers. In the customer‐initiated auction, new arrivals can sequentially trade places with queued customers. We use two novel experimental protocols to examine the behavioral properties of both auction mechanisms. We find that both auction mechanisms improve a queue's efficiency on average and that both perform equally well in terms of efficiency gain. We also find evidence of the sunk‐cost effect but not of the endowment effect. Participants indicated that they found the server‐initiated auction a fairer mechanism than the customer‐initiated auction. When voting between the two auctions, the participants tended to favor the server‐initiated auction.     

A heuristic solution procedure for the multi-item,single-level,limited capacity,lot-sizing problem

The problem to be considered is that of determining lot-sizes for a group of products which are produced at a single workcentre. It is assumed that the requirements for each product are known, period by period, out to the end of some common time horizon. (A reasonable assumption in a Material Requirements Planning context when we are dealing with components of one or more other items already scheduled.) For each product there is a fixed setup cost incurred each time production takes place. Unit production and holding costs are linear. The time required to set up the machine is assumed to be negligible. All costs and production rates can vary from product to product but not with respect to time. In each period there is a finite amount of machine time available that can vary from period to period. The objective is to determine lot-sizes so that 1) costs are minimized, 2) no backlogging occurs and 3) capacity is not exceeded.An exact solution to this complex problem is out of the question. Therefore, a simple heuristic has been developed which guarantees a feasible solution, if one exists. Results of a large number of test problems, including three supplied by industrial sources, are presented. The results indicate that the heuristic will usually generate a very good solution with a relatively small amount of computational effort.     

An international comparison of human resource management objectives and activities

The paper reports on mailed surveys of human resource professionals in Canada, South Africa and Zimbabwe who were asked for their views on the priorities they set in terms of human resource objectives and activities. Respondents were also asked to indicate the challenges facing the field and the resulting changes that may be required in each country. The results indicate considerable agreement between the three countries on the need for flexibility and cost effectiveness, but disagreement on priorities among some other activities. There are major differences between perceptions of immediate and long-term priorities to be set. There is a concern that short-term efficiency may be accorded a priority which prevents due consideration being given to future development and societal issues.     

An algorithm for the generalized transportation problem

This paper describes a new computational technique for solving spatial economic equilibrium problems which are generalizations of the classic transportation problem. This technique makes use of a type of algorithm which has been developed in recent years to compute Kakutani fixed points and solve related problems. Existing algorithms for the generalized transportation problem employ quadratic programming, and therefore require that demand and supply functions be linear. By contrast, the algorithm of this paper can handle demand and supply relationships which are nonlinear or even semi-continuous. It can also handle non-constant transport costs and various other complications. The technique is capable of yielding highly accurate solutions, and appears to be computationally efficient on problems of reasonable size.     

An evaluation of heuristic methods for determining the best table mix in full-service restaurants

Little research has been done on the optimal mix of supply in service businesses that maximizes revenue. Our research context is the full-service restaurant table mix problem. This problem, which is quite new to the literature, finds the optimal number of different size tables for a restaurant to maximize its value (revenue or contribution) generating potential. Specifically, we examine the effectiveness of eight heuristic techniques for the problem using two experiments. The first experiment uses data from a 240-seat full-service restaurant to evaluate all eight heuristics, while the second experiment investigates the performance of selected heuristics under a broader set of environmental factors. The results of our first experiment showed that the better of the simulated annealing heuristic variants yielded the optimal solution in seven of eight test problems, averaging within 0.1% of optimal. Our second experiment showed that the simplest of the models we investigated yielded solutions within 1% of the simulated annealing solution. Finally, we observed that altering the table mix on a daily basis increased performance by over 1% compared to maintaining the optimal weekly table mix.     

A heuristic programming approach to the employee scheduling problem and some thoughts on “managerial robots”

We describe a system for the automatic scheduling of employees in the particular setting in which: the number of employees wanted on duty throughout the week fluctuates; the availabilities of the employees varies and changes from week to week; and a new schedule must be produced each week, by virtue of the changing demand for service.The problem which we address appears in a variety of settings, including: airline reservation offices; telephone offices; supermarkets; fast food restaurants; banks and hotels.Previous approaches to the problem have relied chiefly on formal methods, generally involving one or another variation of linear or integer, mathematical programming. We suggest that except in cases involving very small problems (only a handful of employees) that those approaches have not proven promising, especially where union rules and management requirements impose complex constraints on the problem, and that a heuristic approach has proven to be substantially superior.We set forth the general features of our heuristic approach, which we see as an application of artificial intelligence; we show how, in contrast to other approaches, which design shifts as if employees were always available and try to fit those shifts to employees who are not always available, our system design shifts with deference to the employees' limited availabilities; we suggest that, for a given service level, our system produces schedules with a better “fit”—number of employees actually on duty comparing more favorably with the number wanted; and we state that while, for a given service level, a ‘manual scheduler’ may take up to 8 hours each week to prepare a good schedule, our system, on most micro computers, routinely produces better schedules involving up to 100 employees in about 20 minutes.The scheduling of employees is generally considered to be a managerial function, in the setting of the problem we address. When a craft employee is replaced on an assembly line by a machine which performs the same function, we speak of the replacing mechanism as an industrial robot.We suggest that systems like that which we describe deserve a name, to distinguish them from comparable, computer based systems which do not replace, but rather supplement a manager, and we suggest the name ‘managerial robot’ for such systems.We set forth the characteristics which we feel would justify applying the term ‘managerial robot’ to a computer based system, and suggest that classification is basic to understanding and communication and that just as terms such as decision support systems and expert systems prove useful in our increasingly advanced, technological society, so also the term managerial robot has a place in our scheme of things.Decision support systems do not qualify as managerial robots for the reason that managerial robots don't simply support the decision making process, but rather replace the manager in his performance of a function which, when performed by a human being, is considered a managerial function.Nor do we consider managerial robots to qualify as expert systems. While our scheduling system contains an inference mechanism, and could be enhanced to improve the quality of its schedules thru ‘experience’ (and thus to ‘learn’?), that—lacking a knowledge base in the sense of expert systems-and most of all in replacing rather than supporting the decision maker, the managerial robot needs a term of its own.We elaborate, in this paper, a specific application of our system, and show how the design of shifts, and the placement of breaks, serve to yield a fit whose quality no human scheduler can duplicate.     

An algorithm for the single commodity spatial price equilibrium problem

This paper presents a serial decomposition algorithm for the solution of the static single commodity spatial price equilibrium problem. The computational performance of this algorithm on randomly generated examples suggests that this method is more efficient and requires no more computer storage than other algorithms previously suggested for this problem.     

Staffing and equipment decisions for services: An experimental analysis

Many service-oriented firms face demand/work load variations that occur both within and between days, and seasonally during the year. These service firms tend to develop staffing plans based on peak periods, resulting in substantial idle time during low demand periods. To counter this, some firms hire part-time employees to work peak periods to improve productivity. In this way, the cost per customer/transaction (unit) can be reduced.However, the staffing decision is more complex than just determining the number and timing of the work force. The development of good staffing plans must consider the impact of available work stations like telephone consoles and data entry terminals. To use effectively more personnel during peak periods, the firm must have sufficient work stations to assign this work force. Effective staff scheduling must consider simultaneously the work load variations, employ capabilities, and equipment requirements. This article presents a model that incorporates these factors into the decision-making process and examines their interaction.The model analysis illustrates how uncertainty in work load forecasts and staffing flexibility influence expected cost performance and equipment requirements. A set of computer simulation experiments are conducted using operating data from the proof and encoding departments for Ohio National Bank and Chemical Bank. The results suggest that increased staffing flexibility reduces the needed equipment investment, since part time staff can be scheduled more conveniently to meet varying work loads. Also, basing capital equipment decisions on peak work load levels can substantially increase total operating costs. With these costs explicitly estimated, managers can weigh them against desired service level goals to determine the appropriate balance.     

An empirical comparison of cross-impact models for forecasting sales

This paper compares a set of four cross-impact models: (1) additive, (2) likelihood multiplier, (3) R-space, and (4) a model constructed by the author. This is done by examining a forecasting problem encountered by an industrial firm. The forecasting problem was to study the market trend in order to decide whether to expand the production capacity of a ceramics plant. In spite of their different theoretical premises, the models yielded similar results. However, only the R-space model produced results that differed from the others. The paper also suggests a method that should avoid some internal contradictions of the cross-impact models.     

Chain indices of the cost-of-living and the path-dependence problem: An empirical solution

This paper proposes a new method for estimating true cost-of-living (Konüs) indices, for large numbers of commodities, using data only on prices, aggregate budget shares and aggregate expenditure. Conventional chain indices are path-dependent unless income elasticities are (implausibly) all equal to 1. The method allows this difficulty to be overcome. I show that to estimate a Konüs index, only income and not price elasticities are required. The method is applied to estimate a Konüs price index for 70 products covering nearly all the UK's Retail Prices Index over 1974–2004, using the Quadratic Almost Ideal Demand System. The choice of base year for utility has a significant effect on the index.     

Inflation illusion and the Taylor principle: An experimental study

We develop a simple experimental setting to evaluate the role of the Taylor principle, which holds that the nominal interest rate has to respond more than one-for-one to fluctuations in the inflation rate to exert a stabilizing effect. In our setting, the average inflation rate fluctuates around the inflation target if the computerized central bank obeys the Taylor principle. If the Taylor principle is violated, the average inflation rate persistently deviates from the target. These deviations from the target are less pronounced, if inflation rates cannot be as readily observed as nominal interest rates. This result is consistent with the interpretation that subjects underestimate the influence of inflation on the real return to savings if the inflation rate is only observed ex post.     

An application of goal programming to the desegregration busing problem

This paper develops a goal programming model for obtaining solutions to the desegregation busing problem. The model is compared with the linear programming approach and is applied to 31 schools serving over 14,000 students. Solutions result in potential cost savings of over one-half million dollars.     

Accuracy, unbiasedness and efficiency of professional macroeconomic forecasts: An empirical comparison for the G7

In this paper, we use survey data to analyze the accuracy, unbiasedness and efficiency of professional macroeconomic forecasts. We analyze a large panel of individual forecasts that has not previously been analyzed in the literature. We provide evidence on the properties of forecasts for all G7-countries and for four different macroeconomic variables. Our results show a high degree of dispersion of forecast accuracy across forecasters. We also find that there are large differences in the performances of forecasters, not only across countries but also across different macroeconomic variables. In general, the forecasts tend to be biased in situations where the forecasters have to learn about large structural shocks or gradual changes in the trend of a variable. Furthermore, while a sizable fraction of forecasters seem to smooth their GDP forecasts significantly, this does not apply to forecasts made for other macroeconomic variables.     

村居意象系统与旅游景观资源的保护及利用

认为人文旅游景观资源的合理开发与利用是发展乡村旅游经济的重点研究内容。以湖州市为例,对有形乡村景观和无形乡村景观资源的表现形式、特点、开发利用中存在的问题进行了研究;阐述了村居意象系统构想并阐述了其含义和构建要求。在此基础上,提出了资源保护与利用目标、打造人与效益影响下的乡村旅游资源利用方式的对策建议和基于村居意象系统构建的人文旅游资源开发利用模式。     

转型时期广州城市社会问题探析

在分析社会转型基本涵义的基础之上,以广州市为例,通过问卷调查指出:贫富分化、流动人口、就业压力、社会责任感下降、城乡文化整合等,是转型时期城市社会面临的主要问题,并对如何维持城市社会未来的健康发展提出了个人建议.     

Generalised estimates of diffusion rates for the oxygen blown steel process: An international comparison

The purpose of this study is to build on the results recently obtained by Poznanski (1990). First, the estimation technique is generalised by removing both the symmetric restrictions and the effects of autocorrelated errors that are present in simple logistic functions. Secondly, attention is drawn to the existence and consequences of multicollinearity when non linear techniques are applied to a general exponential. Thirdly, an attempt is made to quantify the importance of market structure and time lags in adoption as determinants of diffusion speed. Finally, a comparison between these generalised results and Poznanski's is made.The study concludes that, by generalising the estimation technique, some significant changes take place. Changes occur in the ordering and magnitude of diffusion speeds, especially amongst the developing and centrally planned economies. Changes also occur in the nature of the diffusion process, and in the importance attributed to market structure and diffusion lags in determining the rate of diffusion. It is also shown that, for some countries, multicollinearity imposes constraints on the type of generality that can be obtained.     

Shake-and-bake algorithms for the identification of nonredundant linear inequalities*

Two probabilistic shake-and-bake algorithms are presented to detect nonredundant constraints in a full dimensional system of linear inequalities. The algorithms proceed by generating a random sequence of points on the boundary of a polyhedron, and by searching for a nonredundant constraint in the direction of a random vector from each point in the sequence. The limiting distribution of the sequence of points generated by the algorithms is proven to be uniform on the boundary of the polyhedron.     

An econometric comparison of uk and german foreign holiday behaviour

Econometric models which explain the generation and distribution of foreign holidays undertaken by UK and German residents are constructed and estimated. These comprise the basic model, a less constrained transformation and a modified model which incorporates supply constraints and habit persistence. Both versions of the basic model are shown to exhibit a structural break across the two sets of origin data, suggesting that habit and/or supply factors are important. The empirical findings also imply that the British regard foreign holidays as luxuries whereas Germans view them as necessities.