Jorge M. Azevedo Santos

Introduction to data envelopment analysis

This chapter introduces the basics of data envelopment analysis techniques, with a short historical introduction and examples of the constant returns to scale model (CRS) and the variable returns to scale (VRS) model. The ratio models are linearized and for both orientations primal and dual models are presented.

An Algorithm to Discover the k-Clique Cover in Networks

In social network analysis, a k-clique is a relaxed clique, i.e., a k-clique is a quasi-complete sub-graph. A k-clique in a graph is a sub-graph where the distance between any two vertices is no greater than k. The visualization of a small number of vertices can be easily performed in a graph. However, when the number of vertices and edges increases the visualization becomes incomprehensible. In this paper, we propose a new graph mining approach based on k-cliques. The concept of relaxed clique is extended to the whole graph, to achieve a general view, by covering the network with k-cliques. The sequence of k-clique covers is presented, combining small world concepts with community structure components. Computational results and examples are presented.

Efficiency Measures in the Agricultural Sector: With Applications

Part I Efficiency Measures and Methods 1 Efficiency Measures in the Agricultural Sector: The Beginning Emiliana Silva, Armando Mendes and Jorge Santos 2 Review of Frontier Models and Efficiency Analysis: A Parametric Approach Ana Sampaio 3 Introduction to Data Envelopment Analysis Jorge Santos, Elsa Rosario Negas and Luis Cavique Santos 4 Superefficiency and Multiplier Adjustment in Data Envelopment Analysis Jorge Santos, Luis Cavique Santos, Armando Mendes Part II Farm Efficiency Applications 5 An Application of Data Envelopment Analysis (DEA) in Azores Dairy Farms Emiliana Silva, Amilcar Arzubi and Julio Berbel 6 Animal Grazing System Efficiency Emiliana Silva, Carlos Santos and Armando Mendes 7 Technical Efficiency of the Spanish Dairy Processing Industry: Do Size and Exporting Matter? Magdalena Kapelko and Alfons Oude Lansink 8 Inefficiency in Animal Production - A Parametric Approach Emiliana Silva and Fatima Venancio 9 Azorean Agriculture Efficiency by PAR Armando B Mendes, Veska Noncheva and Emiliana Silva 10 Sustainable Tourism and Agriculture Multifunctionality by PAR: A Variable Selection Approach Armando Mendes, Veska Noncheva and Emiliana Silva 11 The Importance of Subsidies in Azorean Dairy Farms Efficiency Emiliana Silva and Eusebio Marote 12 Multi-Ouput Technical Efficiency in the Olive Oil Industry and its Relation to the Form of Business Organisation Rafaela Dios-Palomares, Jose M. Martinez-Paz and Angel Prieto 13 Efficiency Assessment: Final Remarks Jorge Santos, Emiliana Silva and Armando Mendes Index

An application of recent developments of Data Envelopment Analysis to the evaluation of secondary schools in Portugal

This paper highlights the potentialities of Data Envelopment Analysis to evaluate the performance of organisations, using the concept of super-efficiency - an extension of DEA which increases its performance - and presents an example from the public sector to illustrate the method. The example selected is that of a school network where a place in a school can be seen as a perishable good, as places which are not occupied during an academic year are wasted. Results for the Portuguese Secondary school network show that the average efficiency of overcrowded schools, that is, those exceeding their capacity, is lower than that of schools which are less crowded. This shows clearly that overcrowded schools, on average, are less efficient in transforming their inputs into academic performance. It is this conviction, seldom proved scientifically, which leads governments and international organisations to recommend planning criteria for public facilities.

Efficiency Measures in the Agricultural Sector: The Beginning

The agricultural productivity is often based on non-parametric models (DEA), or stochastic models (SFA). In this initial article, the editors start by pointing that the models (DEA and SFA) allow estimating the efficiency of the production frontier and their structural forms. Then, it is presented, in general terms, the differences between DEA and SFA models: DEA model involves the use of technical linear programming to construct a non-parametric piecewise surface, and SFA models comprise econometric models with a random variable, or an error term, including two components: one to account for random effects and another to take care of the technical inefficiency effects. Finally, it shows a comparison between the two approaches (SFA and DEA) and the advantages and disadvantages of their utilizations.

An Algorithm to Condense Social Networks and Identify Brokers

In social network analysis the identification of communities and the discovery of brokers is a very important issue. Community detection typically uses partition techniques. In this work the information extracted from social networking goes beyond cohesive groups, enabling the discovery of brokers that interact between communities. The partition is found using a set covering formulation, which allows the identification of actors that link two or more dense groups. Our algorithm returns the needed information to create a good visualization of large networks, using a condensed graph with the identification of the brokers.

Superefficiency and Multiplier Adjustment in Data Envelopment Analysis

Superefficiency is an important extension of DEA that overcomes some limitations of the traditional models, specifically allowing ranking of efficient units and a unique set of weights for those units. Weights restriction is a well-known technique in the DEA field. When those techniques are applied, weights cluster around its new limits, making its evaluation dependent of its levels. This chapter introduces a new approach to weights adjustment by goal programming techniques, avoiding the imposition of hard restrictions that can even lead to unfeasibility. This method results in models that are more flexible.

Efficiency Assessment: Final Remarks

In this concluding chapter the editors make some important remarks on the importance and conclusions of the book as a whole, focusing on its importance, relevance and adequacy to an extended audience of researchers in the efficiency analysis in the agricultural and environment fields.