A Comparison of Due Date Setting,Resource Assignment,and Job Preemption Heuristics for the Multiproject Scheduling Problem*

This research examines a heuristic, rule-based approach for setting due dates in a multiproject, multijob, or assembly shop. Due date estimation is a challenging problem because the operating environment is capacitated, involves the allocation of multiple resources, and allows for the preemption of resources from one project or job to another. The dynamic, continuous arrival of new jobs or orders frequently results in the preemption of resources through the application of managerially determined priority policies. These preemption policies have a significant impact on the ultimate completion time of a job or a project. A three-factor, full-factorial computer simulation experiment is used to assess the relative effectiveness of combinations of four due date setting heuristics, five resource assignment heuristics, and three resource preemption heuristics. Recommendations are made for the selection of due date and resource assignment heuristic combinations under the three preemption policies examined.     

On the Generality of the PERT Average Time Formula

It is well known that the PERT average time formula approximation is related to the Beta distribution assumption. In this note, it is shown that if the formula is modified to use the median instead of the mode, then it becomes a good approximation regardless of distribution assumptions. Applications of the formula beyond project management are highlighted.     

Project Portfolio Selection: A Newsvendor Approach

We consider the problem of balancing the penalties associated with budgetary slack (being underbudget) and cost overruns in the project portfolio selection problem by addressing randomness in project costs and making individual project budgets decision variables. Setting the budget for a single project is shown to be analogous to the newsvendor problem. For related versions of the project portfolio selection problem we provide optimal and heuristic procedures. Numerical experiments are used to test the procedures and provide managerial guidelines. We show project budgets should be set so that each project in the portfolio has the same probability of running over budget, it is better to have a larger number of projects with less than ideal funding compared to a smaller number of projects with ideal funding, and substantial opportunities to select more projects with a higher expected profit are available if an aggregate portfolio budget is used.     

Effects of Erroneous Estimation of Activity Durations on Scheduling and Dispatching a Single Project*

This research examines the effects of erroneous estimation of activity durations on two different approaches for executing a resource-constrained project. The two approaches are scheduling and dispatching. This research is conducted in two phases. Phase one examines the performance of scheduling and dispatching rules in a variety of project environments. These project environments are categorized by three different factors, namely, the order strength of the precedence relationship, the level of resource availability and the size of errors in estimating the activity durations. The results show that scheduling generally produces a shorter project completion time than the heuristic dispatching rules. The results also indicate that project environment affects only the relative performance differences of the scheduling and dispatching rules but not their ranking. Phase two examines the effect of rescheduling. The results show that frequent rescheduling improves the project completion time, while the timing of rescheduling has little impact on the improvement in the project completion time. The results also identify the project environments where rescheduling is beneficial.     

欧盟就业政策及其对我国再就业政策的启示

近年来，失业阴影不仅笼罩着整个西方世界，发展中国家的就业状况同样不容乐观。本文以新一轮世界经济发展和我国再就业工程现状为背景，在分析欧盟就业状况及其政策思路的基础上，提出了借鉴欧盟有关经验，进一步优化我国再就业政策的建议。