Optimal weights in DEA models with weight restrictions

According to a conventional interpretation of a multiplier DEA model, its optimal weights show the decision making unit under the assessment, denoted DMUo, in the best light in comparison to all observed DMUs. For multiplier models with additional weight restrictions such an interpretation is known to be generally incorrect (specifically, if weight restrictions are linked or nonhomogeneous), and the meaning of optimal weights in such models has remained unclear. In this paper we prove that, for any weight restrictions, the optimal weights of the multiplier model show DMUo in the best light in comparison to the entire technology expanded by the weight restrictions. This result is consistent with the fact that the dual envelopment DEA model benchmarks DMUo against all DMUs in the technology, and not only against the observed DMUs. Our development overcomes previous concerns about the use of weight restrictions of certain types in DEA models and provides their rigorous and meaningful interpretation

Study of criteria used to obtain a sustainable bridge

[Otros] The sustainable development of bridges is mainly based on meeting the three pillars of sustainability (economic, social and environmental factors) which have different goals. Each main criterion groups a large number of subcritera. Therefore, achieve a sustainable bridge is a complicate problem that involves a high number of factors in each stage of bridge life-cycle. For this reason, decision-making is a helpful process to solve the sustainability problem. The objective of this work is to review the bridge life-cycle decision-making problems that involve criteria that represent the pillars of the sustainability. While some works only consider criteria related to one or two of these pillars, the most current works consider criteria that involve all the pillars of sustainability. Furthermore, most of the works reviewed only study one stage of bridge life-cycle. This study shows the criteria used in some revised journal articles in each bridge life-cycle phase and, the multi-attribute decision-making used to achieve the sustainability. In addition, a small explanation of the obtained information will be carried out.The authors acknowledge the support from the Ministry of Competitiveness and FEDER funding (Project BIA2014-56574-R)Penadés-Plà, V.; Yepes, V.; García-Segura, T.; Martí Albiñana, JV. (2017). Study of criteria used to obtain a sustainable bridge. ISEC. 1-6. https://doi.org/10.14455/ISEC.res.2017.177S1

Solving DEA models in a single optimization stage: Can the non-Archimedean infinitesimal be replaced by a small finite epsilon?

Single-stage DEA models aim to assess the input or output radial efficiency of a decision making unit and potential mix inefficiency in a single optimization stage. This is achieved by incorporating the sum of input and output slacks, multiplied by a small (theoretically non-Archimedean infinitesimal) value epsilon in the envelopment model or, equivalently, by using this value as the lower bound on the input and output weights in the dual multiplier model. When this approach is used, it is common practice to select a very small value for epsilon. This is based on the expectation that, for a sufficiently small epsilon, the radial efficiency and optimal slacks obtained by solving the single-stage model should be approximately equal to their true values obtained by the two separate optimization stages. However, as well-known, selecting a small epsilon may lead to significant computational inaccuracies. In this paper we prove that there exists a threshold value, referred to as the effective bound, such that, if epsilon is smaller than this bound, the solution to the single-stage program is not approximate but precise (exactly the same as in the two-stage approach), provided there are no computational errors

Visual management of performance with PROMETHEE productivity analysis

Multi-criteria decision analysis has been used to solve many problems. Here we describe an adaptation of PROMETHEE for measuring productivity. The results of PROMETHEE productivity analysis are displayed graphically, permitting the user to distinguish easily between four types of action: efficient, effective, frugal and inefficient actions. The productivity graph can be used for visual management and provides a simple, effective means of improving information communication within an organisation. It enhances transparency and promotes continuous improvement. Steps can be taken to improve ineffective actions using peer(s) on the frontier as example. To illustrate the use of the method we analysed the productivity of British universities. Only two old and two of the most recent universities were found to be on the frontier. Almost all of the most recent universities were classed as frugal and post-92 universities tended to be inefficient. Large old universities were generally classed as effective.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Returns to scale in convex production technologies

The notion of returns to scale (RTS) is well-established in data envelopment analysis (DEA). In the variable returns-to-scale production technology, the RTS characterization is closely related to other scale characteristics, such as the scale elasticity, most productive scale size (MPSS), and global RTS types indicative of the direction to MPSS. In recent years, a number of alternative production technologies have been developed in the DEA literature. Most of these technologies are polyhedral, and hence are closed and convex sets. Examples include technologies with weakly disposable undesirable outputs, models with weight restrictions and production trade-offs, technologies that include several component production processes, and network DEA models. For most of these technologies, the relationship between RTS and other scale characteristics has remained unexplored. The theoretical results obtained in this paper establish such relationships for a very large class of closed convex technologies, of which polyhedral technologies are an important example

Pay for performance in health care: a new best practice tariff-based tool using a log-linear piecewise frontier function and a dual–primal approach for unique solutions

Health care systems worldwide have faced a problem of resources scarcity that, in turn, should be allocated to the health care providers according to the corresponding population needs. Such an allocation should be as much as effective and efficient as possible to guarantee the sustainability of those systems. One alternative to reach that goal is through (prospective) payments due to the providers for their clinical procedures. The way that such payments are computed is frequently unknown and arguably far from being optimal. For instance, in Portugal, public hospitals are clustered based on criteria related to size, consumed resources, and volume of medical acts, and payments associated with the inpatient services are equal to the smallest unitary cost within each cluster. First, there is no reason to impose a single benchmark for each inefficient hospital. Second, this approach disregards dimen sions like quality (and access) and the environment, which are paramount for fair comparisons and benchmarking exercises. This paper proposes an innovative tool to achieve best-practices tariff. This tool merges both quality and financial sustain ability concepts, attributing a hospital-specific tariff that can be different from hospital to hospital. That payment results from the combination of costs related to a set of potential benchmarks, keeping quality as high as possible and higher than a user-predefined threshold, and being able to generate considerable cost savings. To obtain those coefficients we propose and detail a log-linear piecewise frontier function as well as a dual–primal approach for unique solutions.info:eu-repo/semantics/publishedVersio

Integration von Gewichtsrestriktionen in das DEA-Modell nach Charnes, Cooper und Rhodes: exemplarische Optionen und Auswirkungen

Ziel des Beitrags ist es, die Integration von Gewichtsrestriktionen in das DEA-Basismodell nach Charnes, Cooper und Rhodes (CCR-Modell) zu untersuchen. Für ein fiktives Beispiel werden die Ergebnisse der um verschiedene Gewichtsrestriktionen erweiterten DEA-Modelle präsentiert und diskutiert. In einfachen Sensitivitätsanalysen wird der Einfluss ausgewählter Gewichtsrestriktionen auf die Effizienzwerte näher beleuchtet

A Review of Multi-Criteria Decision-Making Methods Applied to the Sustainable Bridge Design

The construction of bridges has been necessary for societies since ancient times, when the communication between and within towns, cities or communities was established. Until recently, the economic factor has been the only one considered in the decision-making of any type of construction process for bridges. However, nowadays, the objective should not be just the construction of bridges, but of sustainable bridges. Economic, social and environmental factors, which form the three pillars of sustainability, have been recently added. These three factors usually have conflicting perspectives. The decision-making process allows the conversion of a judgment into a rational procedure to reach a compromise solution. The aim of this paper is to review different methods and sustainable criteria used for decision-making at each life-cycle phase of a bridge, from design to recycling or demolition. This paper examines 77 journal articles for which different methods have been used. The most used methods are briefly described. In addition, a statistical study was carried out on the Multiple Attribute Decision-making papers reviewed.The authors acknowledge the financial support of the Spanish Ministry of Economy and Competitiveness, along with FEDER funding (BRIDLIFE Project: BIA2014-56574-R). In addition, the authors wish to thanks the comments of Dan M. Frangopol from Center for Advanced Technology for Large Structural Systems.Penadés-Plà, V.; García-Segura, T.; Martí Albiñana, JV.; Yepes, V. (2016). A Review of Multi-Criteria Decision-Making Methods Applied to the Sustainable Bridge Design. Sustainability. 8(12):1295-01-1295-21. https://doi.org/10.3390/su8121295S1295-011295-2181