The surprising effectiveness of earliest operation due-date sequencing

In make-to order production, schedule reliability is very important but still not sufficiently accomplished in industrial practice by the vast majority of companies. It has been known for long that processing the orders at a workstation in the order of their operation due-dates can compensate for lateness in the arrival at the workstation within certain boundaries. The paper analyses the effectiveness of earliest operation due date (EODD) sequencing by comparing it to an optimistic theoretical boundary. The surprising result is that EODD can nearly fully exploit the theoretical potential. It should therefore be used in practice whenever schedule reliability is important, with only few exceptions. Its effectiveness though is increasing with the workstation’s WIP level and thus is in conflict with the objective to reduce WIP levels and throughput times. A simple forecasting model allows to assess the extent to which lateness can be compensated by EODD sequencing and which schedule compliance can be achieved.     

Decision model for product rollover in manufacturing operations

The purpose of this study is to investigate critical decisions when planning for product rollover at a manufacturing company, and how to organise these decisions. A literature review and a case study are used to develop a decision model. The findings indicate that product rollover can be organised in a five-phase decision model. The research quality is strengthened by a structured literature review, but it can be argued that more empirical research is needed for validation. For researchers, this paper contributes with the identification of critical decisions and a model for product rollover. For practitioners, the study highlights the need to acknowledge the importance of product rollover and its role as a competitive weapon. In earlier studies, product rollover has mainly been investigated from a market perspective, so that this study contributes by investigating the issue from a manufacturing perspective.     

THE REPLACEMENT PROBLEM IN FRICTIONAL ECONOMIES: A NEAR‐EQUIVALENCE RESULT

We examine how technological change affects wage inequality and unemployment in a calibrated model of matching frictions in the labor market. We distinguish between two polar cases studied in the literature: a “creative destruction” economy, where new machines enter chiefly through new matches and an “upgrading” economy, where machines in existing matches are replaced by new machines. Our main results are: (i) these two economies produce very similar quantitative outcomes, and (ii) the total amount of wage inequality generated by frictions is very small. We explain these findings in light of the fact that, in the model calibrated to the US economy, both unemployment and vacancy durations are very short, i.e., the matching frictions are quantitatively minor. Hence, the equilibrium allocations of the model are remarkably close to those of a frictionless version of our economy where firms are indifferent between upgrading and creative destruction, and where every worker is paid the same market‐clearing wage. These results are robust to the inclusion of machine‐specific or match‐specific heterogeneity into the benchmark model. (JEL: J41, J64, O33)     

Entscheidungsverhalten von Kunden in Mass Customization-Systemen

Sequential choice processes are ubiquitous in consumer decision making. In each attribute decision, consumers are often faced with different numbers of options which they must trade off in order to make the best possible choice. Thereby, complicated high variety choices at the beginning of a choice process produce a larger trade-off conflict and, thus, initially a greater mental depletion than more simple low variety choices. We examine the strength of mental depletion in sequential choices on individuals’ perceived attractiveness of the firm’s recommended default option at a target choice. We show that consumers who are confronted with difficult high variety choices early in the decision sequence followed by low variety choices initially deplete more than consumers who encounter exactly the same attribute decisions in reverse. As a result, depleted consumers are more likely to fall prey to the recommended default or some perceptually focal options close to the default anchor at target choice succeeding a sequence of decisions.     

Increasing Returns and Social Contagion in Cultural Industries

A formal definition of cultural industries is developed following four distinct features of cultural goods: (a) oversupply, (b) quality uncertainty, (c) network effects and (d) demand reversal. Drawing on economic and socio-psychological notions of ‘network’, increasing returns and social contagion effects are distinguished. Increasing returns may govern the adoption of standards when choices are binary, social contagion explains the diffusion of cultural goods when choices are multiple. Together, the four structural features delineating cultural industries account for curious competitive dynamics prevalent in cultural markets, such as the notorious 10 : 90 proportionality (under which 10% of cultural goods account for 90% of the market), causal ambiguity about the reasons for success, and the formation of fashions. Six managerial recommendations are advanced, focusing on a criticial circulation point triggering self-sustaining diffusion patterns. Finally ‘project-based enterprises’ and ‘network forms of governance’ are identified as the organizational forms most suited to the dynamics of the cultural markets.     

Modified Wald statistics for generalized linear models

Summary: Wald statistics in generalized linear models are asymptotically ² distributed. The asymptotic chi–squared law of the corresponding quadratic form shows disadvantages with respect to the approximation of the finite–sample distribution. It is shown by means of a comprehensive simulation study that improvements can be achieved by applying simple finite–sample size approximations to the distribution of the quadratic form in generalized linear models. These approximations are based on a ² distribution with an estimated degree of freedom that generalizes an approach by Patnaik and Pearson. Simulation studies confirm that nominal level is maintained with higher accuracy compared to the Wald statistics.     

Occupational stress as it relates to higher education,individuals and organizations

This study examined through survey research methodology the degree to which, faculty, administrators and program coordinators, working in higher education, experience stress at work. The Occupational Stress Indicator was used, composed of four compound factors: sources of occupational stress, individual characteristics, coping strategies and the effects of stress. Preliminary findings showed that occupational stress has a negative impact on the degree of satisfaction with their achievement, value and growth, being strongest with faculty and coordinators, (dissatisfaction with career opportunities, personal growth, skill utilization). Another significant outcome was the dissatisfaction of faculty with the organizational design, structure and processes (communication, change implementation, motivation, supervision style, participation in decision-making). All possess individual characteristics of the Type A Scale; they all considered major sources of pressure in their jobs to be their relationships with others, home/work interface, their need to achieve personal and corporate success. Occupational stress has affected their state of health.     

Auswirkungen von Downsizing-Maßnahmen auf das organisationale Commitment der verbleibenden Mitarbeiter: Ein Vorher-Nachher-Vergleich

This study examines the consequences of downsizing efforts on organizational commitment, job satisfaction and work motivation of the remaining workforce (?survivors“) in a middle-sized telecommunication company. Employees were surveyed five months prior to the downsizing process (n=150) and eleven months thereafter (n=160). The assessment of organizational commitment was based on a questionnaire that was developed by Allen and Meyer (1990) within the scope of their three-components-model which includes affective, continuous and normative commitment. Although layoffs — as one part of the whole downsizing process — were not implemented in the investigated company, but only in a sister enterprise, which is part of the same holding, the affective commitment of employees towards their corporation dropped. On the other hand, the normative and the balanced commitment remained constant. Moreover, every second survivor showed reduced job satisfaction and work motivation. It should be noted that although the results of reorganisation and restructuring did not directly affect the employees of the investigated company, the emotional linkage between employees and employer was affected in a negative way. Additional findings from qualitative interviews suggest that restructuring was perceived to cause a crack in the prevailing corporate culture and the psychological contract. In addition, a deterioration of work conditions through work overload resulted.     

$$D_s$$-optimality in copula models

Optimum experimental design theory has recently been extended for parameter estimation in copula models. The use of these models allows one to gain in flexibility by considering the model parameter set split into marginal and dependence parameters. However, this separation also leads to the natural issue of estimating only a subset of all model parameters. In this work, we treat this problem with the application of the \(D_s\)-optimality to copula models. First, we provide an extension of the corresponding equivalence theory. Then, we analyze a wide range of flexible copula models to highlight the usefulness of \(D_s\)-optimality in many possible scenarios. Finally, we discuss how the usage of the introduced design criterion also relates to the more general issue of copula selection and optimal design for model discrimination.