Optimizing lot size and setup time in a JIT environment: a multiple objective application

The just-in-time (JIT) system has been studied extensively and implemented by a number of US firms as an ell'ective production system. The core of JIT involves determination of lot size and setup time reduction so as to increase manufacturing flexibility while minimizing the inventory level. This decision problem usually involves multiple conflicting objectives and mixed-model production. In this paper, goal programming (GP) is applied to a real-world JIT problem involving fabrication of different automotive and industrial rubber composite belts. The model results provide new insights concerning the conflicting nature of several goals, especially between meeting demand and reducing setup or idle time. Also, the GP solution is superior to the current JIT practice of the company.     

A TEST OF THE FORM-RESISTANT CORRELATION HYPOTHESIS: RATINGS, RANKINGS, AND THE MEASUREMENT OF VALUES

A number of researchers have argued that ranking techniquesare more appropriate than rating methods for the measurementof values in surveys. The form-resistant correlation hypothesisproposes that observed associations among values and betweenvalues and other variables should remain invariant across measurementmethods. However, some recent research on parental values forchild qualities suggests that ratings and rankings produce differentcorrelational results. The present study tests the hypothesisthat discrepancies between rating and ranking results are dueto the fact that, when responding to rating questions, somerespondents avoid making difficult choices between valued qualitiesby rating all the qualities as highly and equally desirable.Consistent with this hypothesis, when nondifferentiating respondentsare removed from the analyzed sample, the substantive resultsof analyses of rating data resemble the results typically obtainedusing ranking data. This suggests that ranking may be the superiormethod for measuring values.     

OPTIMAL 'MISMATCH' AND PROMOTIONS

Seeming 'mismatches' in which workers are either under-or overqualified, are shown to be optimal. From the firm's point of view, although turnover will be positively related to overqualification, training costs will be inversely related to overqualification. Further, overqualified workers constitute a pool from which promotions are made. Workers enter seeming mismatches due to search and mobility costs and because of opportunities for promotion. Estimates using a unique data set indicate that workers who are overqualified at hire receive less training and more promotions, and that workers overqualified for their current job are more likely to quit.     

Inconsistency of the MLE for the Joint Distribution of Interval-Censored Survival Times and Continuous Marks

Abstract.  This paper considers the non-parametric maximum likelihood estimator (MLE) for the joint distribution function of an interval-censored survival time and a continuous mark variable. We provide a new explicit formula for the MLE in this problem. We use this formula and the mark-specific cumulative hazard function of Huang & Louis (1998) to obtain the almost sure limit of the MLE. This result leads to necessary and sufficient conditions for consistency of the MLE, which imply that the MLE is inconsistent in general. We show that the inconsistency can be repaired by discretizing the marks. Our theoretical results are supported by simulations.     

Class voting and class consciousness in Canada

Plusieurs hypotheses existent, qui tentent d'expliquer la faiblesse du vote de classe au Canada. Je tente ici de reformuler certaines de ces hypothPses, i partir de leurs postulats i1'6gard de la conscience de classe et de la formation de classe. Deux types d'explications sont identifies: celles, d'abord, qui soutiennent que le bas niveau de conscience de classe au Canada est la cause de I'absence de formation de classe; et celles pour qui l'inverse est vrai. Toutes les hypotheses considerees trouvent des donnees qui les supportent dans la ricente Etude electorale nationale. I1 est actuellement impossible de choisir entre elles, alors que les donnees disponibles ont une valeur limitee et que des problemes de niveaux d'analyse restent i resoudre. On devrait considerer les deux modes d'explication comme interactifs, et aussi vraisemblables l'un que l'autre.
Many hypotheses have been advanced to explain the low levels of class voting in Canada. This article reformulates a number of these in terms of their assumptions about class consciousness and class formation. Explanations are divided into those which hold the society's low level of class consciousness responsible for the lack of class formation, and those which propose the reverse. Evidence from recent National Elections Study data contains support for all of the hypotheses, and it is concluded that choosing between them is currently impossible because of data limitations and level-of-analysis problems. The two lines of argument should be regarded as interactive and equally plausible.     

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.