R. Tavakkoli-Moghaddam, S. Mahmoodi,
Volume 21, Issue 2 (5-2010)
Abstract
A data envelopment analysis (DEA) method can be regarded as a useful management tool to evaluate decision making units (DMUs) using multiple inputs and outputs. In some cases, we face with imprecise inputs and outputs, such as fuzzy or interval data, so the efficiency of DMUs will not be exact. Most researchers have been interested in getting efficiency and ranking DMUs recently. Models of the traditional DEA cannot provide a completely ranking of efficient units however, it can just distinguish between efficient and inefficient units. In this paper, the efficiency scores of DMUs are computed by a fuzzy CCR model and the fuzzy entropy of DMUs. Then these units are ranked and compared with two foregoing procedures. To do this, the fuzzy entropy based on common set of weights (CSW) is used. Furthermore, the fuzzy efficiency of DMUs considering the optimistic level is computed. Finally, a numerical example taken from a real-case study is considered and the related concept is analyzed.
Yahia Zare Mehrjerdi,
Volume 23, Issue 3 (9-2012)
Abstract
Abstract
The purpose of this article is to present a system dynamics (SD) model for studying the interconnections among human being weight, eating habit, exercise, body fat, take-in medication, drugs-uses, and the health problems in general. Due to the fact that all of these factors have direct and indirect impacts on the expenses that insurance company have to pay this author is proposing a systems thinking approach for determining the interconnections among the factors and uses the concept of system dynamics to simulate and determine the behavior of the system. To do so, this author has reviewed key point about the system thinking, related theories, and system dynamics. Next, models in the form of causal loops presenting the interconnections between weight factor and health problems are developed and discussed. Thereafter, a flow diagram of model is constructed and the overall expenses are studied. Expense rates are classified as: operational expenses (OE), treatment expenses (TE), Medication expenses (ME), Hospitality expenses (HE), and Drug treatment expenses (DE). This article makes a significant contribution to the health study issues due to the fact that it shows how a factor such as weight can have impacts on hearth attack, blood pressure, and blood sugar, to mention a few, and how relate all these to the overall expenses that an insurance company have to pay at last. Since, to the best of this author's knowledge, this is the first study that relates weight to health problem using systems thinking concepts and system dynamics approach it makes significant contribution to health literature.
Seyed Hossein Razavi Hajiagha, Shide Sadat Hashemi, Hannan Amoozad Mahdiraji,
Volume 25, Issue 3 (7-2014)
Abstract
Data envelopment analysis operates as a tool for appraising the relative efficiency of a set of homogenous decision making units. This methodology is applied widely in different contexts. Regarding to its logic, DEA allows each DMU to take its optimal weight in comparison with other DMUs while a similar condition is considered for other units. This feature is a bilabial characteristic which optimizes the performance of units in one hand. This flexibility on the other hand threats the comparability of different units because different weighting schemes are used for different DMUs. This paper proposes a unified model for determination of a common set of weights to calculate DMUs efficiency. This model is developed based on a multi objective fractional linear programming model that considers the original DEA's results as ideal solution and seeks a set of common weights that rank the DMUs and increase the model's discrimination power. Comparison of the proposed method with some of the previously presented models has shown its advantages as a DMUs ranking model.
