R. Lawrence LaForge

Perceived relevance and quality of POM journals: a decade later

This research is a 10-year update on the rankings of perceived relevance and quality of selected Production and Operations Management (POM) journals that was reported by Barman et al. (1991) [Journal of Operations Management 10 (2), 194‐212)]. The results show some changes in the perceptions of journals over the past decade. Some journals are perceived to be extremely relevant to POM research, but not particularly of “high” quality. For other journals, the reverse is true — “high” quality is perceived but the published studies are not considered particularly relevant to POM. The Journal of Operations Management remained atop the relevance rankings and retained its position among the top three journals for quality. The study identifies factors that the respondents say influence their perception of journal quality. Finally, the paper finds some evidence that association with the editorial board of a journal affects one’s perceptions of the quality and relevance of that journal.

On Using Buffer Stock to Combat Schedule Instability

Schedule instability is a major problem in companies using material requirements planning (MRP) systems. The effectivenesss of using buffer stock to combat nervousness in the master production schedule (MPS) of an MRP system is investigated. An example scenario illustrates the need for caution in using buffer stock for reducing schedule instability. Detailed simulation results are presented which suggest the need for further research to understand the role of buffer stock in achieving stable master production schedules.

MRP lot sizing with multiple purchase discounts

Abstract Five MRP lot sizing models are modified to accommodate multiple purchase discounts and tested in an experiment involving different levels of requirements variability, discount attractiveness, and order cost. The testing of multiple purchase discounts is an extension of earlier research that compared MRP lot sizing models under a simplified discount structure involving a single price break [3, 4, 7]. The models tested here have either been implemented in some actual MRP systems or have been proposed as effective models by other researchers. Five hundred test problems were solved by each model, generating 2500 cost figures for comparison. The results indicate that an incremental version of part-period balancing and, to a lesser extent, the least unit cost method are the best models of those tested.

A model to estimate service levels when a portion of the master production schedule is frozen

Abstract An illustrative example is presented to show how freezing can affect performance of the master production schedule (MPS). An analytical expression is then derived for the expected customer service level when a specified number of orders in the MPS is frozen. The analytical model is used to estimate the effects of MPS freezing in a variety of situations. Controlled simulation experiments are then run to assess the usefulness of the analytical model in estimating customer service under more complex situations. The results suggest that the impact of MPS freezing on customer service is predictable and not as severe as might be anticipated.

A study of replanning frequencies in a material requirements planning system

Abstract A simulation model is used to examine the effects of different replanning intervals in a material requirements planning (MRP) system. Replanning frequencies of monthly, twice monthly, weekly, twice weekly, daily, and twice daily are simulated in an MRP environment in which timing changes can occur in the master production schedule. The replanning frequencies are evaluated on the basis of end-item service rate, inventory value, and the number of open order change notices. The results suggest that inventory may increase with more frequent MRP replanning and that the widely-accepted practice of making weekly MRP runs may not always be the best alternative.

The Evolution of Enterprise Resource Planning

Today, many Enterprise Resource Planning (ERP) systems are run on a network of personal computers. Their features include a client/server architecture supported by a distributed relational database system with query and reporting capabilities, electronic data interchange capability to communicate with both suppliers and customers, decision support systems for managers, a graphical user interface, and standard application programming interfaces.