Constructing a fuzzy Shewhart control chart for variables when uncertainty and randomness are combined

In this paper we introduce a fuzzy chart for variables which is used in situations when uncertainty and randomness are combined. It is showed that the Shewhart chart’s control limits must be adjusted in these situations. However, this chart is based on a fuzzy acceptance region and this method arises when a decision should be made by referring to the grade of a sample statistic belonging to the fuzzy acceptance region.     

A control rule for recruitment planning in engineering consultancy

The most valuable asset of a professional service firm is its people. Owing to the high labor turnover, staffing decision is very critical in its operations. We take engineering consultancy as a professional service and emphasize the importance of developing knowledge stock of skilled consultants in a planned manner for efficient productivity management. Our focus is management of knowledge-mix, which is the mix of consultants at different productivity levels. Our model is designed to determine the steady-state number of consultant-mix to meet demand at a desired service level. This is done through the use of control theory and chance constrained programming.      

库存-整合优化问题研究综述

库存-运输整合优化（Inventory—Transportation Integrated Optimization，ITIO）问题是供应链协调的重要方面。库存与运输“效益悖反”的特点增加了ITIO问题的复杂性。文章将对库存-运输整合优化的研究现状进行综述，以期总结成果，并找出新的研究方向。     

Probabilistic assignment problem with multi-unit demands: A generalization of the serial rule and its characterization

We study a probabilistic assignment problem when agents have multi-unit demands for objects. We first introduce two fairness requirements to accommodate different demands across agents. We show that each of these requirements is incompatible with stochastic dominance efficiency (henceforth, we use the prefix “sd” for stochastic dominance) and weak sd-strategy-proofness, unless all agents have unitary demands. We next introduce a new incentive requirement which we call limited invariance. We explore implications of these requirements in combination of consistency or converse consistency.Our main result is that the generalized serial rule, which we propose as an adaptation of the serial rule to our setting, is the only rule satisfying sd-efficiency, the sd proportional-division lower-bound, limited invariance, and consistency. Uniqueness persists if we replace the sd proportional-division lower-bound by sd normalized-no-envy, or consistency by converse consistency, or both. The serial rule in Bogomolnaia and Moulin (2001) is characterized as a special case of our generalized serial rule.     

A control function approach for testing the usefulness of trending variables in forecast models and linear regression

Many predictors employed in forecasting macroeconomic and finance variables display a great deal of persistence. Tests for determining the usefulness of these predictors are typically oversized, overstating their importance. Similarly, hypothesis tests on cointegrating vectors will typically be oversized if there is not an exact unit root. This paper uses a control variable approach where adding stationary covariates with certain properties to the model can result in asymptotic normal inference for prediction regressions and cointegration vector estimates in the presence of possibly non-unit root trending covariates. The properties required for this result are derived and discussed.     

Signed social structure optimization for shift assignment in the nurse scheduling problem

This paper develops a mathematical framework that relies on modern social network analysis theories for treating the nurse team formation and nurse scheduling (shift assignment) problems, accounting for signed social connections. These problems lie in assigning nurses to teams/shifts such that the constraints regarding both the working regulations and nurses preferences are satisfied. Recent research indicates the dependence of nursing team performance on team social structure; however, so far, the social structure considerations have not been explicitly incorporated into the mathematical formulations of the nurse scheduling problem. The presented framework introduces models that quantitatively exploit such dependence. This paper explores instances of Nurse Team Formation Problem (NTFP) and Nurse Scheduling Problem (NSP) incorporating signed social structure with the measures based on such network structures as edges, full dyads, triplets, k-stars, balanced and unbalanced triangles, etc., in directed, signed networks. The paper presents the integer programming formulations for NTFP and NSP, and a problem-specific heuristic that performs variable-depth neighborhood search to tackle NTFP instances with signed social structures. Computational results for a real-world problem instance with 20 nurses are reported. The insights obtained from the presented framework and future research directions are discussed.     

The effect of uncertainty and instability on dynamic economic models with an application to cournot oligopoly

Consider a dynamic discrete-time economic model in which a state-dependent payoff is earned during each period. We give conditions which ensure that a mean preserving increase in the riskiness of the model's parameters increases (or decreases) the expected payoff earned during n periods.     

Portfolio optimization for an investor with a benchmark

The most common equity mandate in the financial industry is to try to outperform an externally given benchmark with known weights. The standard quantitative approach to do this is to optimize the portfolio over short time horizons consecutively, using one-period models. However, it is not clear that this approach actually yields good performance in the long run. We provide a theoretical justification to this methodology by verifying that applying the one-period benchmark-relative mean-variance portfolio, i.e., the industry standard optimal portfolio, continuously is in fact the solution to a specific continuous time portfolio optimization problem: a maximum expected utility problem for an investor who is compared against a benchmark and evaluates her performance based on exponential utility at a deterministic future date.     

The market for corporate control in professional football: is there an agency problem?

This paper identifies the nature of agency problems in professional football in the UK. Conflicting elements within director-owners'objective functions combined with highly concentrated ownership rights are sources of agency problems, manifest by the poor financial performance of many clubs. Arguably, a club's supporters influence its output implying that supporters may be considered as an input.
Given this, theory suggests that efficiency may be enhanced if supporters possess more property rights in their respective clubs.     

A Bayesian estimator for stochastic frontier models with errors in variables

A Bayesian estimator is proposed for a stochastic frontier model with errors in variables. The model assumes a truncated-normal distribution for the inefficiency and accommodates exogenous determinants of inefficiency. An empirical example of Tobin??s Q investment model is provided, in which the Q variable is known to suffer from measurement error. Results show that correcting for measurement error in the Q variable has an important effect on the estimation results.     

Simultaneous optimization of land use and transportation: A synthesis of the quadratic assignment problem and the optimal network problem

The problem of designing jointly a land use plan and a transportation network for a new town is formalized as a combinatorial programming problem which can be considered as an extension of the Koopmans-Beckmann problem. Accessibility and capital costs are the criteria taken into account to evaluate a plan. One exact technique and several heuristic techniques are reported and evaluated.     

A chain ratio-type estimator in finite population double sampling using two auxiliary variables

Summary In this paper we construct a chain ratio-type estimator using two auxiliary variables. The performance of the constructed estimator relative to the simple mean, ratio-type estimate based on double sampling andChand's ratio-type estimator is investigated. A numerical illustration is given.     

A model for irreversible investment with construction and revenue uncertainty

This paper presents a model of investment in projects that are characterized by uncertainty over both the construction costs and revenues. Both processes are modeled as spectrally negative Lévy jump-diffusions. The optimal stopping problem that determines the value of the project is solved under fairly general assumptions. It is found that the current value of the benefit-to-cost ratio (BCR) decreases in the frequency of negative shocks to the construction process. This implies that the cost overruns that can be expected if one ignores such shocks are increasing in their frequency. Based on calibrated data, the model is applied to the proposed construction of high-speed rail in the UK and it is found that its economic case cannot currently be made and is unlikely to be met at any time in the next decade. In addition it is found that ignoring construction uncertainty leads to a substantial probability of an erroneous decision being taken.     

A genetic algorithm for the partial binary constraint satisfaction problem: an application to a frequency assignment problem

We describe a genetic algorithm for the partial constraint satisfaction problem. The typical elements of a genetic algorithm, selection, mutation and cross-over, are filled in with combinatorial ideas. For instance, cross-over of two solutions is performed by taking the one or two domain elements in the solutions of each of the variables as the complete domain of the variable. Then a branch-and-bound method is used for solving this small instance. When tested on a class of frequency assignment problems this genetic algorithm produced the best known solutions for all test problems. This feeds the idea that combinatorial ideas may well be useful in genetic algorithms.     

Runs in an ordered sequence of random variables

Let be independent and identically distributed random variables with continuous distribution function. Denote by the corresponding order statistics. In the present paper, the concept of -neighbourhood runs, which is an extension of the usual run concept to the continuous case, is developed for the sequence of ordered random variables      

Important considerations in using statistical procedures to control for nuisance variables in non-experimental studies

In this paper, it is argued that the effects of statistically controlling for confounding variables in non-experimental studies have received insufficient attention. One of the reasons for this inattention is likely because many researchers do not fully appreciate what a statistical control strategy entails and how the use of such a strategy can affect the hypotheses actually tested in a study. In order to address these issues, this article (a) considers what the use of statistical control entails computationally, (b) reviews studies in which researchers have focused on the unique variance added by a predictor in testing a hypothesis, and (c) shows how this practice is not always sufficient for understanding research results.     

Panel data methods for fractional response variables with an application to test pass rates

We revisit the effects of spending on student performance using data from the state of Michigan. In addition to exploiting a dramatic change in funding in the mid-1990s and subsequent nonsmooth changes, we propose nonlinear panel data models that recognize the bounded nature of the pass rate. Importantly, we show how to estimate average partial effects, which can be compared across many different models (linear and nonlinear) under different assumptions and estimated using many different methods. We find that spending has nontrivial and statistically significant effects, although the diminishing effect is not especially pronounced.     

优化工程造价控制的策略探讨

文章分析了优化工程造价控制的必要性和重要性,并就优化工程造价控制的要求和原则展开了分析,在此基础上提出了各环节优化工程造价控制的方法和措施。