THE COEFFICIENT OF VARIATION AS A FACTOR IN MRP RESEARCH

This paper investigates the use of the coefficient of variation (CV) as a measure of requirements lumpiness (the amount of variation in requirements from period to period) in material requirements planning (MRP) research. CV is used as a factor in MRP research even though it is limited as a measure. Any sequence of requirements will have a unique CV, but any CV can represent a variety of requirements sequences. This limitation raises questions concerning the robustness of CV as a measure. In this paper, two other aspects of the requirements sequence for a given CV are investigated: the procedure used to generate the requirements and the manner in which the requirements are grouped. A simulation comparison of selected lot-sizing techniques is used to conduct the investigation. With respect to these two (new) aspects of the requirements sequence, CV appears to be a robust measure.     

THE TIMING OF LABOR TRANSFERS IN DUAL RESOURCE-CONSTRAINED SYSTEMS: “PUSH” VS. “PULL” RULES*

Altough the dual resource-constrained (DRC) system has been studied, the decision rule used to determine when workers are eligible for transfer largely has been ignored. Some earlier studies examined the impact of this rule [5] [12] [15] but did not include labor-transfer times in their models. Gunther [6] incorporated labour-transfer times into his model, but the model involved only one worker and two machines. No previous study has examined decision rules that initiate labor transfers based on labor needs (“pull” rules). Labor transfers always have been initiated based on lack of need (“push” rules). This study examines three “pull” variations of the “When” labor-assignment decision rule. It compares their performances to the performances of two “push” rules and a comparable machine-limited system. A nonparametric statistical test, Jonckheere's S statistic, is used to test for significance of the rankings of the rules: a robust parametric multiple-comparison statistical test, Tukey's B statistic, is used to test the differences. One “pull” and one “push” decision rule provide similar performances and top the rankings consistently. Decision rules for determining when labor should be transferred from one work area to another are valuable aids for managers. This especially is true for the ever-increasing number of managers operating in organizations that recognize the benefits of a cross-trained work force. Recently there has been much interest in cross-training workers, perhaps because one of the mechanisms used in just-in-time systems to handle unbalanced work loads is to have cross-trained workers who can be shifted as demand dictates [8]. If management is to take full advantage of a cross-trained work force, it need to know when to transfer workers.     

COMMENTS ON “COST INCREASES DUE TO DEMAND UNCERTAINTY IN MRP LOT SIZING”: A VERIFICATION OF ORDERING PROBABILITIES

In a recent article in this journal, De Bodt and Van Wassenhove [1] presented analytic derivations related to lot-sizing behavior under uncertainty. Although their models appear to have been verified in the aggregate by simulation experiments, detailed justifications for several of the derivations are missing. The present paper looks at De Bodt and Van Wassenhove's analysis and provides verifications of (and corrections to) the ordering probabilities and order cycles used by the authors to estimate the cost effects of forecast errors in the particular operating environment studied. The probabilities simulated in this study also generate additional insight into the “system nervousness” caused by lot-sizing and forecast errors.     

MANUFACTURING STRATEGY ON THE “S” CURVE

The concept and techniques of “manufacturing strategy” offer managers the opportunity to use their production function as a strategic weapon in competition, an apparently attractive objective. Yet after about 25 years, the use of manufacturing in corporate strategy (MCS) as a management practice is not widespread. In contrast, however, in academic literature it appears to be flourishing and rapidly growing in popularity. This paper seeks to answer this apparent paradox, beginning with the history of MCS as it was developed as a theory of design to enable a manufacturing system to be focused on a key competitive task. Common criticisms of MCS, such as “tradeoffs,” “focus” and “undynamic,” are examined and refuted as valid reasons for its only modest usage. Instead, three “new” problems in the MCS concept and its techniques are suggested as genuine needs for the completion of the theory and for its becoming more universally understood and used by industrial managers.     

A Reply to Williamson's “Outsourcing …”

A recent article by Oliver Williamson essentially comprises a critique of supply chain management (SCM) from the perspective of his own field, transaction‐cost economics. Here is one reader's response. SCM can indeed be faulted for inflated rhetoric, among other sins. I believe, however, that the two fields have much to learn from each other.     

TOWARD UNDERSTANDING THE CONTENTS OF THE “BLACK BOX” FOR PREDICTING COMPLEX DECISION-MAKING OUTCOMES

The purpose of this research is to show the usefulness of three relatively simple nonlinear classification techniques for policy-capturing research where linear models have typically been used. This study uses 480 cases to assess the decision-making process used by 24 experienced national bank examiners in classifying commercial loans as acceptable or questionable. The results from multiple discriminant analysis (a linear technique) are compared to those of chi-squared automatic interaction detector analysis (a search technique), log-linear analysis, and logit analysis. Results show that while the four techniques are equally accurate in predicting loan classification, chi-squared automatic interaction detector analysis (CHAID) and log-linear analysis enable the researcher to analyze the decision-making structure and examine the “human” variable within the decision-making process. Consequently, if the sole purpose of research is to predict the decision maker's decisions, then any one of the four techniques turns out to be equally useful. If, however, the purpose is to analyze the decision-making process as well as to predict decisions, then CHAID or log-linear techniques are more useful than linear model techniques.     

TOWARD A “NEW ARCHITECTURE” FOR POM

The field of POM is steadily expanding its scope. This allows us to pursue interesting new fields of inquiry and makes us ever more relevant to the needs of practitioners. But it also increases the risk that over time our efforts will become fragmented and unfocused, causing us to slowly lose our sense of community and break up into separate camps. In this paper I ask, “What kind of new organizing framework, or ‘architecture,’ will allow us to maintain our sense of community as our interests diverge?” I describe the experience of one academic organization that faced a similar problem several years ago and how the situation was resolved. This experience leads us to propose a possible solution to Pom's emerging problem: engage with real operations managers and focus our efforts on helping them deal with the actual problems they are facing in today's complex and fast‐changing world.     

AFFECTIVE RESPONSES WITHIN A COMPLEX DECISION-MAKING TASK: THE INFLUENCE OF “PERCEPTUALLY” ILL-STRUCTURED PROBLEMS

The perceptual effects of varying levels of expert advice for potentially improving on strategic decisions were examined in conjunction with goals. The amounts of advice about decision alternatives, as well as assigned goals ranging from “nearly impossible” to “easy,” were manipulated. The task used was complex and functioned perceptually as an “ill-structured” problem. Mixed results indicated that more advice significantly affected satisfaction but advice in general had little influence on effort. On the other hand, as goal difficulty decreased, satisfaction and effort significantly increased. Easy goals were superior to more difficult ones within this perceptually ill-structured decision-making situation.     

Response to “Revisiting ISO 14000 Diffusion: A New ”Look“ at the Drivers of Certification”

In Corbett and Kirsch (2001), we used a simple regression in an exploratory investigation of drivers of global diffusion of ISO 14000 certification. We found that ISO 9000 certification levels, environmental treaties ratified, and exports as a proportion of GDP were the main significant variables, where the environmental measure may be moderated by GDP per capita. In his replication study, Vastag (2004, in this issue) analyzes the same data using more visual techniques, specifically regression trees, and finds support for the significance of ISO 9000 certification levels and environmental treaties ratified, but not for export‐propensity. Vastag raises a number of relevant methodological issues, to which we add some perspectives here.     

A NOTE ON “COMMON DUE WINDOW SCHEDULING”

Kramer and Lee recently addressed a common due window scheduling problem with earliness and tardiness penalties, where earliness and tardiness penalty factors are constant and the common window size is given. They showed that the problem is polynomial when the location of the due window is a decision variable. For the case where the location of the due window is given, the problem is also polynomial when the latest due date is greater than or equal to the makespan, and they proposed a pseudopolynomial dynamic programming algorithm to find an optimal schedule when the latest due date is less than the makespan. In this note we address the problem for the case where the location of the due window is given. Specifically, we show that the problem is polynomial if the window location is unrestricted, and present a more efficient dynamic program algorithm to optimally solve the problem if the window location is restricted. The concepts of unrestricted and restricted window locations are defined in this note.     

Notes and Communications “A DECISION THEORY EXAMPLE IN FOOTBALL”: A COMMENT*

Janssen and Daniel analyzed the choice between a one- or a two-point conversion for a particular game situation in college football. Their decision criteria was maximum expected utility based on a von Neumann-Morgenstern utility function defined over the games outcomes. An alternative approach based on a stochastic dominance criterion is presented that does not rely on knowledge of the relative importance of tying vs. winning; rather, it relies on a notion of consistency in the sequential problem.     

REPLY TO: “ON THE SENSITIVITY OF BRAND-CHOICE SIMULATIONS TO ATTRIBUTE IMPORTANCE WEIGHTS”

Our reply to Curry, Louviere, and Augustine's critique of our earlier paper focuses on differences in motivation between our research and theirs. Our interest in the problem relates to the possible incorporation of self-explicated evaluations in conjoint data collection methods; subsequent to the appearance of our original paper, we have developed hybrid models that combine elements of self-explicated (compositional) and conjoint (decompositional) data collection procedures. As far as we can surmise from their critique, Curry, Louviere, and Augustine are concerned with much broader strategic issues relating share of choices in the consumer population to changes in the shape of attribute weight distributions, shape of the Pareto tradeoff boundary, and so on.     

The global “war for talent”

In this paper we examine the “global war for talent,” the factors that impact it, and organizations' responses to it. Using a comprehensive search of more than 400 contemporary academic and business press articles, the paper reviews relevant research and reassesses the “talent war.” We posit that the dominant approaches to the “talent war” based on a scarcity state of mind and action, often characterized by a tactical and exclusive top talent or “star” focus, are being challenged by the emergence of a more evolutionary paradigm. This new paradigm adopts more strategic, innovative, cooperative and generative approaches which we describe as creative ‘talent solutions.’ The paper also highlights implications for future research, teaching and development in the field.     

Note on “many-sided shadow prices”

It has been previously shown, with the aid of a simple example, that linear programmes may have two different non-negative marginal values at the optimum if the solution is degenerate. It is demonstrated in this note that other marginal values exist which may take negative values.