Integrated framework for robustness analysis using ratio-based efficiency model with application to evaluation of Polish airports

We consider a problem of evaluating efficiency of Decision Making Units (DMUs) based on their deterministic performance on multiple consumed inputs and multiple produced outputs. We apply a ratio-based efficiency measure, and account for the Decision Maker׳s preference information representable with linear constraints involving input/output weights. We analyze the set of all feasible weights to answer various robustness concerns by deriving: (1) extreme efficiency scores and (2) extreme efficiency ranks for each DMU, (3) possible and necessary efficiency preference relations for pairs of DMUs, (4) efficiency distribution, (5) efficiency rank acceptability indices, and (6) pairwise efficiency outranking indices. The proposed hybrid approach combines and extends previous results from Ratio-based Efficiency Analysis and the SMAA-D method. The practical managerial implications are derived from the complementary character of accounted perspectives on DMUs׳ efficiencies. We present an innovative open-source software implementing an integrated framework for robustness analysis using a ratio-based efficiency model on the diviz platform. The proposed approach is applied to a real-world problem of evaluating efficiency of Polish airports. We consider four inputs related to the capacities of a terminal, runways, and an apron, and to the airport׳s catchment area, and two outputs concerning passenger traffic and number of aircraft movements. We present how the results can be affected by integrating the weight constraints and eliminating outlier DMUs.     

Efficiency of well-diversified portfolios: Evidence from data envelopment analysis

In this work, we evaluate eight exchange traded funds (ETFs) and their benchmark index (the KOSPI 200 Index), based on the Sharpe ratio and the Treynor ratio and find that the performance of these well-diversified portfolios are quite poor relative to individual stocks. Investors׳ preference to avoid the well-diversified portfolios would be related to this poor performance. However, we empirically show that ETFs and the KOSPI 200 Index are the most efficient investment instruments with respect to the new performance measure designed on the basis of the data envelopment analysis (DEA) methodology. Examining the panel data over the period between 2003 and 2014 indicates that well-diversified portfolios improve the efficiency by adjusting the input variables (σ and β). Furthermore, they do so more effectively as they mature.     

The inferring of preferences from indifferences in multicriteria decision analysis

Rivett [5] has proposed that an approximate preference ordering may be deduced from statements of pairwise indifferences between decision alternatives by using multi-dimensional scaling. In this paper it is demonstrated that much stronger evaluations of preference are possible by applying formal statistical inferential procedures to a simple parametric model, relating indifference to closeness on a scale defined by a linear function of attribute values. This can be used to screen out a considerable proportion of less desirable decision alternatives. The method is illustrated by application to Rivett's problem of the hypothetical Town of Brove, for which a satisfactory matching with Rivett's utilities is obtained. It is also shown that the method can provide useful preference orderings on the basis of less than 20% of all possible pairwise comparisons between alternatives.     

多层次结构DEA模型及其应用

在评价实践中,评价者通常倾向采用一组指标或指标体系对DMUs展开相对全面的评价,不同层次指标的重要性也往往不同。然而,标准DEA模型在DMUs有限条件下经常会面临无法直接处理过多的评价指标,也无法直接处理多层次指标的问题。本文从DEA模型中的序结构和测度出发,构建了符合多层次指标体系特点,能相对全面地体现评价者价值导向,且具有合理区分能力的多层次结构DEA模型,并以15个机构基础研究的投入-产出评价为例展开了应用分析。     

Multiple facility location on a network with linear reliability order of edges

We study the problem of locating facilities on the nodes of a network to maximize the expected demand serviced. The edges of the input graph are subject to random failure due to a disruptive event. We consider a special type of failure correlation. The edge dependency model assumes that the failure of a more reliable edge implies the failure of all less reliable ones. Under this dependency model called Linear Reliability Order (LRO) we give two polynomial time exact algorithms. When two distinct LRO’s exist, we prove the total unimodularity of a linear programming formulation. In addition, we show that minimizing the sum of facility opening costs and expected cost of unserviced demand under two orderings reduces to a matching problem. We prove NP-hardness of the three orderings case and show that the problem with an arbitrary number of orderings generalizes the deterministic maximum coverage problem. When a demand point can be covered only if a facility exists within a distance limit, we show that the problem is NP-hard even for a single ordering.     

The design of socially optimal decisions in a consensus scenario

Several situations of conflict between basic social principles can crop up during a consensus searching process. The majority principle and respect for minority groups is a possible example of a conflictive situation between two social principles. In this paper, we outline a specific consensus searching scenario, where individual preferences are expressed by “pairwise” comparison matrices. The set of compromise consensuses between the majority and minority principles is determined using a procedure based upon an adaptation of Yu's p-metric distances. Finally, we use three different theoretical approaches – utility theory, p-metric distance functions and bargaining theory – to obtain the social optimum from the set of compromise consensuses. The links and differences among the three approaches are analysed. Finally, the working of the proposed theoretical framework is illustrated with the help of a forestry case study.     

共识条件下最小最大妥协的直觉模糊数集结方法研究

直觉模糊集（IFS）理论是描述广泛模糊事物的重要工具。为减小决策过程中个体偏好值与群体偏好值的差异，协调个体与群体间矛盾，提升决策结果的执行效率，本文提出最小化最大妥协度（Minimize maximum compromise）的决策准则。给出直觉模糊环境下的，个体偏好值的集结算法及决策方法，并分别考虑了有无共识条件、有无决策主体权重的三类决策情景。最后给出算例，验证本文方法的有效性，结果表明，相较于I-IFOWG算子，本文方法能够有效降低群体决策中个体的妥协程度。     

Interactive Hazards Education Program for Youth in a Low SES Community: A Quasi‐Experimental Pilot Study

A pilot study of an interactive hazards education program was carried out in Canberra (Australia), with direct input from youth participants. Effects were evaluated in relation to youths’ interest in disasters, motivation to prepare, risk awareness, knowledge indicators, perceived preparedness levels, planning and practice for emergencies, and fear and anxiety indicators. Parents also provided ratings, including of actual home‐based preparedness activities. Using a single group pretest‐posttest with benchmarking design, a sample of 20 youths and their parents from a low SES community participated. Findings indicated beneficial changes on a number of indicators. Preparedness indicators increased significantly from pre‐ to posttest on both youth (p < 0.01) and parent ratings (p < 0.01). Parent ratings reflected an increase of just under six home‐based preparedness activities. Youth knowledge about disaster mitigation also was seen to increase significantly (p < 0.001), increasing 39% from pretest levels. While personalized risk perceptions significantly increased (p < 0.01), anxiety and worry levels were seen either not to change (generalized anxiety, p > 0.05) or to reduce between pre‐ and posttest (hazards‐specific fears, worry, and distress, ps ranged from p < 0.05 to < 0.001). In terms of predictors of preparedness, a number of variables were found to predict posttest preparedness levels, including information searching done by participants between education sessions. These pilot findings are the first to reflect quasi‐experimental outcomes for a youth hazards education program carried out in a setting other than a school that focused on a sample of youth from a low SES community.     

Inducement of Nonexistent Order by the Analytic Hierarchy Process*

An apparently unreported problem facing decision makers who use AHP is described. It is demonstrated that conventional AHP and some of its variants (the ideal mode, and the pairwise aggregated approach, PAHAP) can induce ordering even when no order exists. It is also shown that all three approaches can induce different orderings and that the orderings are sensitive to innocuous changes. Thus, even absent addition or deletion of alternatives, the decision maker relying on AHP or these variants can be seriously misled.     

On the etiology of conflict cultures

Conflict has long been conceived as a fundamental part of all organizational systems. Yet the literature on conflict is largely divorced from its organizational roots and instead focuses on general processes of conflict management at the individual and small group levels of analysis. To re-establish the organizational basis of conflict, we develop a macro-theory of conflict cultures, or shared norms that specify how conflict should be managed in organizational settings. We propose a typology of conflict cultures that draws upon two dimensions – active versus passive conflict management norms and agreeable versus disagreeable conflict management norms – and discuss the etiology of four distinct conflict cultures: dominating conflict cultures (active and disagreeable), collaborative conflict cultures (active and agreeable), avoidant conflict cultures (passive and agreeable), and passive–aggressive conflict cultures (passive and disagreeable). We discuss top-down processes (e.g., leadership, organizational structure and rewards, industry, community, and societal factors) and bottom-up processes (e.g., personality, demographics, values and social networks) through which these conflict cultures develop. We explore both positive and negative organizational outcomes associated with each conflict culture, as well as moderators of proposed effects. We conclude with theoretical, practical, and empirical implications of a conflict culture perspective.     

On threshold BDDs and the optimal variable ordering problem

Many combinatorial optimization problems can be formulated as 0/1 integer programs (0/1 IPs). The investigation of the structure of these problems raises the following tasks: count or enumerate the feasible solutions and find an optimal solution according to a given linear objective function. All these tasks can be accomplished using binary decision diagrams (BDDs), a very popular and effective datastructure in computational logics and hardware verification. We present a novel approach for these tasks which consists of an output-sensitive algorithm for building a BDD for a linear constraint (a so-called threshold BDD) and a parallel AND operation on threshold BDDs. In particular our algorithm is capable of solving knapsack problems, subset sum problems and multidimensional knapsack problems. BDDs are represented as a directed acyclic graph. The size of a BDD is the number of nodes of its graph. It heavily depends on the chosen variable ordering. Finding the optimal variable ordering is an NP-hard problem. We derive a 0/1 IP for finding an optimal variable ordering of a threshold BDD. This 0/1 IP formulation provides the basis for the computation of the variable ordering spectrum of a threshold function. We introduce our new tool azove 2.0 as an enhancement to azove 1.1 which is a tool for counting and enumerating 0/1 points. Computational results on benchmarks from the literature show the strength of our new method.     

Evaluation of multi-objective optimization approaches for solving green supply chain design problems

This paper evaluates the applicability of different multi-objective optimization methods for environmentally conscious supply chain design. We analyze a case study with three objectives: costs, CO₂ and fine dust (also known as PM – Particulate Matters) emissions. We approximate the Pareto front using the weighted sum and epsilon constraint scalarization methods with pre-defined or adaptively selected parameters, two popular evolutionary algorithms, SPEA2 and NSGA-II, with different selection strategies, and their interactive counterparts that incorporate Decision Maker׳s (DM׳s) indirect preferences into the search process. Within this case study, the CO₂ emissions could be lowered significantly by accepting a marginal increase of costs over their global minimum. NSGA-II and SPEA2 enabled faster estimation of the Pareto front, but produced significantly worse solutions than the exact optimization methods. The interactive methods outperformed their a posteriori counterparts, and could discover solutions corresponding better to the DM preferences. In addition, by adjusting appropriately the elicitation interval and starting generation of the elicitation, the number of pairwise comparisons needed by the interactive evolutionary methods to construct a satisfactory solution could be decreased.     

基于一致性度量的概率模糊语言多属性群决策方法

人们通常习惯用语言术语来表达他们的偏好，因此概率型语言术语集（Probabilistic Linguistic Term Set，PLTS）在决策过程中有着十分重要的作用。目前PLTS的研究刚刚起步，有关PLTS的相关研究没有关注到一致性度量的问题，对于PLTS的多属性群决策方法有待进一步研究。首先，给出了一种新的PLTS的集结方法，并且在已有的PLTS可能度公式的基础上，构建了PLTS的相似度量方法，在此基础上，进一步提出了基于PLTS一致性度量的多属性群决策方法。该方法在各决策者权重未知的情况下，考虑到各决策者之间的一致性。首先，定义PLTS的一致性度量公式，确定决策者权重；并根据PLTS的集结方法，集结各决策者的评价信息；最后，利用可能度公式对PLTS进行排序。通过案例分析验证了该方法的可行性和优越性。     

基于社交网络分析的区间二元语义群决策方法研究

通过基于Steiner点的区间二元语义集结方法,将评价信息通过相关转化规则量化为对应的二维坐标系中的坐标点集,运用植物模拟生长算法获取对应区间点集的Steiner点(专家群体最优结集点,即群体共识点),按照逆映射关系还原为二元语义集结信息,从而提出一种基于社交网络分析和专家自信偏好关系的区间二元语义群决策问题的新方法。结合专家自信程度系数和社交网络结构中的影响力调整专家主观权重,结合专家相对重要系数与群体相似度系数获取客观权重,最终确定专家综合权重,并对方案进行择优排序。通过算例分析说明方法的可行性和有效性。     

Popularity at minimum cost

We consider an extension of the popular matching problem in this paper. The input to the popular matching problem is a bipartite graph $G = (\mathcal{A}\cup\mathcal{B},E)$ , where $\mathcal{A}$ is a set of people, $\mathcal{B}$ is a set of items, and each person $a \in\mathcal{A}$ ranks a subset of items in order of preference, with ties allowed. The popular matching problem seeks to compute a matching M ^? between people and items such that there is no matching M where more people are happier with M than with M ^?. Such a matching M ^? is called a popular matching. However, there are simple instances where no popular matching exists. Here we consider the following natural extension to the above problem: associated with each item $b \in\mathcal{B}$ is a non-negative price cost(b), that is, for any item b, new copies of b can be added to the input graph by paying an amount of cost(b) per copy. When G does not admit a popular matching, the problem is to “augment” G at minimum cost such that the new graph admits a popular matching. We show that this problem is NP-hard; in fact, it is NP-hard to approximate it within a factor of $\sqrt{n_{1}}/2$ , where n ₁ is the number of people. This problem has a simple polynomial time algorithm when each person has a preference list of length at most 2. However, if we consider the problem of constructing a graph at minimum cost that admits a popular matching that matches all people, then even with preference lists of length 2, the problem becomes NP-hard. On the other hand, when the number of copies of each item is fixed, we show that the problem of computing a minimum cost popular matching or deciding that no popular matching exists can be solved in O(mn ₁) time, where m is the number of edges.     

Multiversity of the twenty-first century – examining opportunities for integrating community engagement in planning curricula

Abstract

This paper examines student-community engagement activity in planning. This is a subset of university–community engagement, and is a point of overlap between such engagement and planning education. Community engagement activity enables students to learn in situ practical skills within live projects, while community partners may benefit from technical knowhow, and labour input. Based on a UK-wide survey and three in-depth case studies, the paper explores the pedagogical designs underpinning community engagement activities involving students, as well as the various capacities in which the different participants – students, instructors and community members – act. The analysis reveals considerable diversity in approaches. An alignment of student engagement activities in the planning curriculum with emerging transformative co-learning models of university-community engagement could offer novel opportunities for the discipline of planning and their impact on communities as well as the fields standing in today’s multiversities.     

Three price elasticities of demand

Elasticity of demand is a measure of market response to a change in price. Three definitions of elasticity of demand are commonly found in the literature: (1) ε_p = point elasticity, defined for a given point on the demand function and relies on the derivative of the function at that point; (2) ε_a = arc elasticity, defined for the midpoint of an arc connecting two points, irrespective of the shape of the demand function; (3) ε = relative change elasticity, defined for two given points as minus the ratio of the relative volume increment to the relative price increment. Of the three, ε_p is the most widely cited and has the merit that marginal revenue is zero at ε_p = 1. It is also convenient when curves with ε_p = constant can be fitted to price-demand data. In practice, apart from the fact that ε_p is often difficult to determine, management is mainly concerned with discrete increments and not marginal changes, and in this respect ε_a is regarded as more useful. However, the relative change elasticity ε is preferable in all practical applications, both because relative increments refer to a given base period (instead of a midpoint, as in the case of ε_a), and because of the simplicity of using it in the analysis of company performance.     

One Person,Many Votes: Divided Majority and Information Aggregation

This paper shows that information imperfections and common values can solve coordination problems in multicandidate elections. We analyze an election in which (i) the majority is divided between two alternatives and (ii) the minority backs a third alternative, which the majority views as strictly inferior. Standard analyses assume voters have a fixed preference ordering over candidates. Coordination problems cannot be overcome in such a case, and it is possible that inferior candidates win. In our setup the majority is also divided as a result of information imperfections. The majority thus faces two problems: aggregating information and coordinating to defeat the minority candidate. We show that when the common value component is strong enough, approval voting produces full information and coordination equivalence: the equilibrium is unique and solves both problems. Thus, the need for information aggregation helps resolve the majority's coordination problem under approval voting. This is not the case under standard electoral systems.     

Linear solution schemes for Mean-SemiVariance Project portfolio selection problems: An application in the oil and gas industry

We study the Mean-SemiVariance Project (MSVP) portfolio selection problem, where the objective is to obtain the optimal risk-reward portfolio of non-divisible projects when the risk is measured by the semivariance of the portfolio׳s Net-Present Value (NPV) and the reward is measured by the portfolio׳s expected NPV. Similar to the well-known Mean-Variance portfolio selection problem, when integer variables are present (e.g., due to transaction costs, cardinality constraints, or asset illiquidity), the MSVP problem can be solved using Mixed-Integer Quadratic Programming (MIQP) techniques. However, conventional MIQP solvers may be unable to solve large-scale MSVP problem instances in a reasonable amount of time. In this paper, we propose two linear solution schemes to solve the MSVP problem; that is, the proposed schemes avoid the use of MIQP solvers and only require the use of Mixed-Integer Linear Programming (MILP) techniques. In particular, we show that the solution of a class of real-world MSVP problems, in which project returns are positively correlated, can be accurately approximated by solving a single MILP problem. In general, we show that the MSVP problem can be effectively solved by a sequence of MILP problems, which allow us to solve large-scale MSVP problem instances faster than using MIQP solvers. We illustrate our solution schemes by solving a real MSVP problem arising in a Latin American oil and gas company. Also, we solve instances of the MSVP problem that are constructed using data from the PSPLIB library of project scheduling problems.