An evaluation of flow-shop scheduling algorithms for makespan reduction in a stochastic environment

This paper addresses the problem of makespan reduction and improvement in related performance measures in the stochastic flow shop. The experimental design addresses the issues of the problem size in terms of the number of jobs and machines, the bottleneck location within the production facility, and the processing time distribution and sensitivity to variance. In other words, many of the assumptions that are typically made in the published literature are violated in favour of a more realistic production basis. Experiments are performed via simulation to examine the performance of several well known flow-shop scheduling algorithms and one new algorithm in this challenging environment. The authors conclude that distributional effects and bottleneck considerations can play a role in the performance of the various algorithms considered. This paper further indicates that the problem size also tends to drive the effectiveness of the scheduling strategies examined, and presents information regarding interesting interaction effects between the problem size and the other elements of experimental concern.     

INVESTIGATIONS CONCERNING THE DYNAMICS OF CONSUMER BEHAVIOR IN UNCERTAIN ENVIRONMENTS

This paper reports the results of several experiments investigating dynamic consumer behavior. When consumers know their incomes and prices but are uncertain about their preferences, we find that they typically adopt a two-step approach to locating optimal consumption bundles. Initially, a grid search method is employed; this is followed by a gradient search method. An interesting phenomenon observed in many of our experiments is a tendency to consume a bundle well away from the optimum, immediately after the optimum is located. The effects of income and price changes are also studied.     

THE EXTERNAL VALIDITY OF EXPERIMENTAL ECONOMICS TECHNIQUES: ANALYSIS OF DEMAND BEHAVIOR

This paper examines the parallelism which exists between demand behavior determined from the sale of a private good in an actual "real world" field setting and in a laboratory auction setting. The demand behavior observed in the two settings is significantly the same leading to the corroboration of the thesis that there is often correspondence between laboratory and real world behavior.     

EFFECTS OF BENEFITS APPEALS, MANDATORY APPEALS, AND VARIATIONS IN STATEMENTS OF CONFIDENTIALITY ON COMPLETION RATES FOR CENSUS QUESTIONNAIRES

This study examines the effects of two different prominentlydisplayed appeals in combination with two different prominentlydisplayed confidentiality assurances on mail-back completionrates for census questionnaires. The experiment was carriedout on a national probability sample of 30,000 household units,using occupant-addressed questionnaires that contained the contentof the 1990 decennial census short form. Neither the benefitsappeal nor the variation between two confidentiality assuranceshad a significant effect on completion rates. The mandatoryappeal, however, significantly improved completion rates, evenwhen it appeared on the envelope only.     

Segmentation and wage determination

Dans leurs écrits récents sur la segmentation socio-économique, les Américains ont utilise des données secondaires recueillies dans le secteur industriel, pour démontrer que les arguments qui veulent que les salaires soient fixés par la population active ou fonctionelle, étaient limités. A l'aide de données recueillies principalement dans des maisons de commerce canadiennes, cette étude explore les effets d'une notion alternative du fonctionnement de la segmentation, sur le processus d'établissement des salaires. En employant de nouvelles techniques de classification, on a identifié trois groupes économiques de base, et examiné les différents aspects de la fixation des salaires à l'intérieur de ces groupes économiques. On a particulièrement montré que la perspective de segmentation pouvait fournir une réinterprétation intéressante des profile réguliers de l'expérimentation des salaires.
Recent American literature on socioeconomic segmentation has employed secondary data gathered at the industrial level to demonstrate the limitations of functionalist or human capital explanations of earnings determination. In this paper, we utilize primary Canadian data collected from business establishments to explore the effects of an alternative operationalization of the segmentation notion on the wage determination process. Using some new classificatory techniques, we identify three basic economic clusters, or segments, and examine the distinctive aspects of wage determination within these economic groups. In particular, we show that the segmentation perspective can provide an interesting reinterpretation of standard experience-earning profiles.     

DOES THE TAX SYSTEM FAVOR INVESTMENT IN HIGH-TECH OR SMOKE-STACK INDUSTRIES?

In this paper, we examine whether differential use of depreciable assets gives rise to differential tax treatment of high-technology industries relative to other industries. We calculate the total effective tax rate on a marginal investment in each of 34 assets, and weighting by the use of these assets, we calculate total effective tax rates for 73 industries. We find considerable variation within the high-tech sector and within the more traditional sector, but for the case of a taxable firm with a given debt/equity ratio, we do not find any systematic differences between overall rates in the two sectors.     

USING RUN-LENGTH DISTRIBUTIONS OF CONTROL CHARTS TO DETECT FALSE ALARMS

Run-length distributions for various statistical process-control charts and techniques for computing them recently have been reported in the literature. The real advantages of knowing the run-length distribution for a process-control chart versus knowing only the associated average-run length of the chart have not been exploited. Our purpose is to use knowledge of the run-length distribution as an aid in deciding if an out-of-control signal is a true signal or merely a false alarm. The ability to distinguish between true and false signals is important, especially in operations where it is costly to investigate the causes of out-of-control conditions. Knowledge of the run-length distribution allows us to compute likelihood ratios, which are simple to calculate and to interpret and which are used to determine the odds of obtaining an out-of-control signal at a particular run length when a shift in the process mean actually has occurred vis-a-vis no such shift. We extend our analysis in a Bayesian sense by incorporating prior information on the distribution of the shift size of the process mean, combined with the likelihood ratio obtained from the run-length distribution, to determine if a shift larger than a critical size has occurred. We give examples for the Shewhart chart, the exponentially weighted moving-average chart, and the special-cause control chart for processes with autocorrelated observations. The examples show that the current recommended usage of the average-run length alone as a guide for determining whether a signal is a false alarm or otherwise can be misleading. We also show that the performance of the traditional charts, in terms of their average-run length, can be enhanced in many instances by using the likelihood-ratio procedure.