A commonsense approach to portfolio planning

For the diversified firm, business portfolio planning offers a way of determining its individual businesses' roles and developing a synergistic corporate strategy. In practice, however, the common tools of portfolio planning—the growth/share and market attractiveness/business position matrices—present problems in that often neither of the matrices is precisely suitable for a given individual business. This article makes use of modifications of the growth/share and market attractiveness/business position matrices in order to make them more operational. The authors believe that a step-by-step ‘shirt-sleeve’ approach to portfolio planning can make this type of analysis accessible and invaluable to a small diversified firm, as well as providing insights to larger corporations with formal planning departments.     

Strategic planning--the role of the chief executive

Failure to see strategic planning as a process and ineffective CEO involvement are two reasons for failures in strategic planning. This article outlines the stages in an effective strategic planning process, discusses the appropriate role or roles for the CEO or leader in each stage, and defines the expected results from effective strategic planning.     

Interfacing aggregate plans and master production schedules via a rolling horizon feedback procedure

Aggregate planning and master scheduling are two important levels of a hierarchical production planning process. They serve as the front end of production and operations planning and control systems. It is imperative to have the front end well planned and coordinated. In this study, we demonstrate that a rolling horizon feedback procedure can be an effective coordination mechanism for interfacing aggregate planning and master scheduling. Each time the schedule is rolled ahead, the feedback of performance results from master scheduling provides the aggregate planning subsystem useful information for improving its planning activities. Our experiments show that there are at least three factors that make a rolling horizon procedure attractive: (i) the use of a horizon with a fractional portion of a seasonal cycle, (ii) high smoothing costs, and (iii) high setup costs. Using rolling horizons reduces the total aggregate costs in these situations relative to not using rolling horizons. The potential impacts of the rolling-horizon strategy are greater under some circumstances than others.     

The Microeconomics of Efficient Group Behavior: Identification1

Consider a group consisting of S members facing a common budget constraint p'ξ=1: any demand vector belonging to the budget set can be (privately or publicly) consumed by the members. Although the intragroup decision process is not known, it is assumed to generate Pareto‐efficient outcomes; neither individual consumptions nor intragroup transfers are observable. The paper analyzes when, to what extent, and under which conditions it is possible to recover the underlying structure—individual preferences and the decision process—from the group's aggregate behavior. We show that the general version of the model is not identified. However, a simple exclusion assumption (whereby each member does not consume at least one good) is sufficient to guarantee generic identifiability of the welfare‐relevant structural concepts.     

MODELING THE TIME DISTRIBUTION OF RECIDIVISM: APPLICATIONS AND LIMITATIONS IN CRIMINAL JUSTICE SYSTEM PLANNING

Existing criminal justice system models give scant attention to the timing of recidivism, a key system phenomenon. Using statistical techniques, several aggregate exponential models for recidivism are developed that extend earlier work. Published empirical data permit calibration and comparison with the model's results. Discussion of the model's rationale and possible refinement is accompanied by suggested planning and policy uses.     

基于投产点库存的随机综合生产计划模型研究

以企业基于投产点法的生产与库存控制策略为研究起点,分析了随机需求条件下生产系统服务水平与库存水平的数量关系,并将产品在计划期间的平均库存量引入综合生产计划模型。模型中计划期产量是与产品需求具有相同分布的随机变量,模型的优化目标是通过确定最佳的投产库存量和生产系统服务水平,求得相应的计划期产量区间。提出了模型的计算机辅助求解算法,并采用案例分析验证了模型的有效性。     

Methodology for the Calculation of Annualized Incremental Risks in Systems of Dams

In the past few years, the field of dam safety has approached risk informed methodologies throughout the world and several methodologies and programs are appearing to aid in the systematization of the calculations. The most common way of implementing these calculations is through the use of event trees, computing event probabilities, and incremental consequences. This methodology is flexible enough for several situations, but its generalization to the case of systems of several dams is complex and its implementation in a completely general calculation methodology presents some problems. Retaining the event tree framework, a new methodology is proposed to calculate incremental risks. The main advantage of this proposed methodology is the ease with which it can be applied to systems of several dams: with a single risk model that describes the complete system and with a single calculation the incremental risks of the system can be obtained, being able to allocate the risk of each dam and of each failure mode. The article shows how both methodologies are equivalent and also applies them to a case study.     

The Social Construction of Planning Systems: A Strategic-Relational Institutionalist Approach

Abstract

This article reflects on a theoretical framework for the analysis of planning systems based on an institutionalist planning theory broadened with Jessop's strategic-relational approach. The aim is to explore the concept of the planning system with an actor—structure perspective so as to underline possible research consequences for analyses and comparisons of planning systems. The article highlights the interactions of actors and social institutional elements, clarifying the strategic-relational nature of a planning system and the dialectical process at the basis of its changes and evolutions.     

多品种集约生产计划问题的模糊方法

提出具有模糊需求量和模糊能力约束以及资本水平约束的多品种类集约生产计划问题 的模糊优化模型及模糊解方法. 通过对模糊需求量和模糊等式的描述,提出了模糊需求环境下 生产- 库存平衡方程的两种等价的描述方法, 并给出了模糊等式的实用解释. 建立了具有模 糊需求量和模糊能力约束集约生产计划问题的优化模型FMAPP ,并给出了求解模型的参数规 划方法.     

On the number of local minima for the multidimensional assignment problem

The Multidimensional Assignment Problem (MAP) is an NP-hard combinatorial optimization problem occurring in many applications, such as data association, target tracking, and resource planning. As many solution approaches to this problem rely, at least partly, on local neighborhood search algorithms, the number of local minima affects solution difficulty for these algorithms. This paper investigates the expected number of local minima in randomly generated instances of the MAP. Lower and upper bounds are developed for the expected number of local minima, E[M], in an MAP with iid standard normal coefficients. In a special case of the MAP, a closed-form expression for E[M] is obtained when costs are iid continuous random variables. These results imply that the expected number of local minima is exponential in the number of dimensions of the MAP. Our numerical experiments indicate that larger numbers of local minima have a statistically significant negative effect on the quality of solutions produced by several heuristic algorithms that involve local neighborhood search.Partially supported by the NSF grant DMI-0457473.     

Corporate long-range planning groups—Some different approaches

This paper investigates several atypical roles of formal long-range planning groups and some reasons for their appearance. The study is based on three separate surveys covering 115 companies in eight industries located in both England and the United States. The authors first identify functions based on their own research and the literature which appear to make up a typical planning group role. Twenty-four of the 115 planning groups surveyed very considerable as well as sytematically from the norm. They are classified into three major categories described as (1) capital budgeting groups, (2) project development groups, and (3) think tank groups.     

Education,Mobility and Employers’ Monopsony Power: A Search‐theoretic Analysis

Abstract. We analyse the efficiency of schooling choices in a wage‐posting search equilibrium model with on‐the‐job search. The workers have multidimensional skills and the search market is segmented by technology. Education determines the scope — or adaptability— of individual skills. Individuals obtain schooling to leave unemployment more quickly and to climb the wage ladder rapidly through job‐to‐job mobility — that is, to speed up job shopping. Education reduces firms’ monopsony power in the wage determination by improving workers’ mobility. As a result, the wage distribution shifts rightward with aggregate schooling. However, the ratio of vacant jobs to job seekers also falls in each sector. Either one or the other externality may dominate, implying, respectively, under‐ or over‐education. A combination of minimum wage and schooling fee can decentralize the efficient allocation.     

Regression Versus Causation,Revisited

I recently discussed pitfalls in attempted causal inference based on reduced‐form regression models. I used as motivation a real‐world example from a paper by Dr. Sneeringer, which interpreted a reduced‐form regression analysis as implying the startling causal conclusion that “doubling of [livestock] production leads to a 7.4% increase in infant mortality.” This conclusion is based on: (A) fitting a reduced‐form regression model to aggregate (e.g., county‐level) data; and (B) (mis)interpreting a regression coefficient in this model as a causal coefficient, without performing any formal statistical tests for potential causation (such as conditional independence, Granger‐Sims, or path analysis tests). Dr. Sneeringer now adds comments that confirm and augment these deficiencies, while advocating methodological errors that, I believe, risk analysts should avoid if they want to reach logically sound, empirically valid, conclusions about cause and effect. She explains that, in addition to (A) and (B) above, she also performed other steps such as (C) manually selecting specific models and variables and (D) assuming (again, without testing) that hand‐picked surrogate variables are valid (e.g., that log‐transformed income is an adequate surrogate for poverty). In her view, these added steps imply that “critiques of A and B are not applicable” to her analysis and that therefore “a causal argument can be made” for “such a strong, robust correlation” as she believes her regression coefficient indicates. However, multiple wrongs do not create a right. Steps (C) and (D) exacerbate the problem of unjustified causal interpretation of regression coefficients, without rendering irrelevant the fact that (A) and (B) do not provide evidence of causality. This reply focuses on whether any statistical techniques can produce the silk purse of a valid causal inference from the sow's ear of a reduced‐form regression analysis of ecological data. We conclude that Dr. Sneeringer's analysis provides no valid indication that air pollution from livestock operations causes any increase in infant mortality rates. More generally, reduced‐form regression modeling of aggregate population data—no matter how it is augmented by fitting multiple models and hand‐selecting variables and transformations—is not adequate for valid causal inference about health effects caused by specific, but unmeasured, exposures.     

Uncertainty Reduction Approaches,Uncertainty Coping Approaches,and Process Performance in Financial Services

Developing a better understanding of the impact of uncertainty on process performance has been recognized as an important research opportunity in service design ( Hill, et al., 2002 ). Within this general research stream, our study focuses on the question of what managers can do to most effectively address operational uncertainty and mitigate its negative effects. To begin to address this question, we report on an exploratory study using a sample of professionals in the financial‐services industry who acted as informants on 108 financial‐services processes. These professionals were sampled from a population of graduates of a university in the northeastern region of the United States who were employed in the financial‐services industry. Based on these processes, we empirically examine the relationship between responses to operational uncertainty and process performance after controlling for customer mix, other uncertainty sources, and process type characteristics. Our findings suggest that process improvement—an uncertainty reduction approach related to the internal functioning of the process—as well as several uncertainty coping approaches are associated with better performing processes. However, uncertainty reduction approaches related to customer involvement with, and demands on, the process are not associated with better performing processes. We discuss the implications of our findings for determining what actions managers can take to reduce the negative performance effects of operational uncertainty and how managers can decide which of these actions to take. We conclude with a discussion of the limitations of our study.     

THE CONCEPT AND MEASUREMENT OF CENTRALITY–AN INFORMATION APPROACH

The complexity of interdependent structural systems greatly complicates the analysis of any single structure. This is particularly the case when a structure represents some behavioral process. For this reason it is necessary to devise measures which can differentiate qualitatively and quantitatively between structures as well as between subsets (or points) of a particular structure. For example, consider the authority structures of two different organizations. They exhibit similarities and differences which a behavioral analyst tries to identify and explain. Typically, both similarities and differences are compared by structural indices which, on the basis of past data and prior information, tend to reflect certain organizational traits. The purpose of this paper is to investigate one particularly important index—centrality. Centrality conveys the notion that points in a structure are not all ‘equal’. This ‘inequality’ vis-a-vis the structure creates a situation in which certain points will be more ‘central’ than others. In this paper we first identify the characteristics of centrality and observe how they may relate to behavioral research. We then develop a procedure for measuring centrality which is based on information theory.     

2-Distance vertex-distinguishing index of subcubic graphs

This paper addresses the performance of scheduling algorithms for a two-stage no-wait hybrid flowshop environment with inter-stage flexibility, where there exist several parallel machines at each stage. Each job, composed of two operations, must be processed from start to completion without any interruption either on or between the two stages. For each job, the total processing time of its two operations is fixed, and the stage-1 operation is divided into two sub-parts: an obligatory part and an optional part (which is to be determined by a solution), with a constraint that no optional part of a job can be processed in parallel with an idleness of any stage-2 machine. The objective is to minimize the makespan. We prove that even for the special case with only one machine at each stage, this problem is strongly NP-hard. For the case with one machine at stage 1 and m machines at stage 2, we propose two polynomial time approximation algorithms with worst case ratio of \(3-\frac{2}{m+1}\) and \(2-\frac{1}{m+1}\), respectively. For the case with m machines at stage 1 and one machine at stage 2, we propose a polynomial time approximation algorithm with worst case ratio of 2. We also prove that all the worst case ratios are tight.     

Why Reduced-Form Regression Models of Health Effects Versus Exposures Should Not Replace QRA: Livestock Production and Infant Mortality as an Example

Do pollution emissions from livestock operations increase infant mortality rate (IMR)? A recent regression analysis of changes in IMR against changes in aggregate “animal units” (a weighted sum of cattle, pig, and poultry numbers) over time, for counties throughout the United States, suggested the provocative conclusion that they do: “[A] doubling of production leads to a 7.4% increase in infant mortality.” Yet, we find that regressing IMR changes against changes in specific components of “animal units” (cattle, pigs, and broilers) at the state level reveals statistically significant negative associations between changes in livestock production (especially, cattle production) and changes in IMR. We conclude that statistical associations between livestock variables and IMR variables are very sensitive to modeling choices (e.g., selection of explanatory variables, and use of specific animal types vs. aggregate “animal units). Such associations, whether positive or negative, do not warrant causal interpretation. We suggest that standard methods of quantitative risk assessment (QRA), including emissions release (source) models, fate and transport modeling, exposure assessment, and dose-response modeling, really are important—and indeed, perhaps, essential—for drawing valid causal inferences about health effects of exposures to guide sound, well-informed public health risk management policy. Reduced-form regression models, which skip most or all of these steps, can only quantify statistical associations (which may be due to model specification, variable selection, residual confounding, or other noncausal factors). Sound risk management requires the extra work needed to identify and model valid causal relations.     

A Comparison of Three Joint Ordering Inventory Policies*

This paper evaluates the performance of a joint ordering inventory policy which was first suggested and characterized by Renberg and Planche [14]. This paper shows that the policy is easily characterized for Poisson demands. This policy is then compared with two other joint ordering policies—the well-known (S, c, s) or can-order policy of Balintfy [3] and the recent periodic policies suggested by Atkins and lyogun [2]. For a continuous review operating environment, the Renberg and Planche policy utilizes a group reorder point and a combined order quantity (Q), with each item maintaining an order-up-to level (S). For the can-order policy, each item in the product group has a must-order point (s), a can-order point (c) and an order-up-to level (S). The periodic policies require that item orders be grouped at some fixed scheduled intervals. Using long-run total average costs as the basis, it is shown that no one policy is superior to the others in all the examples tested. In some cases, the Renberg and Planche policy performs surprisingly well.     

Designing an ADP planning process

A great deal has been written about the frustrations of carrying out long range planning in large organizations. Although far less has been written about ADP planning, similar frustrations (as well as benefits) have been suggested.The case study described in this article deals with the recent experiences of a large, federal regulatory agency— the Food and Drug Administration—in the design and implementation of an ADP planning process from 1974 to the present. Although the process was designed to meet the Agency's specific needs, many of the lessons learned will be useful to others contemplating a process for their organization (public or private).     

How managers decide to use planning models

Recent published reports and surveys have shown that a growing number of corporations and government agencies are using decision models not only for lower level scheduling and resource allocation but also for short-range and long-range planning. Although the literature has described in some detail the types of models used and the ways in which they are used, limited attention has been paid to the ways in which managers decide whether or not to use these models. This paper, which is based on a series of case studies, suggests that the decision to use planning models is made not by performing a comprehensive cost benefit analysis, but by the use of a reference model—that is, an existing model, sometimes in a competitive organization, similar to the one being considered.