Browsing by Author "Topcu, Ilker"

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    Editorial for the Special issue on Multiple Criteria Decision Making models
    (Emerald, 2020-12-01) Aktas, Emel; Topcu, Ilker; Kucukaltan, Berk
    This special issue idea came to life with Prof. Ilker Topcu hosting the 25th International Conference on Multiple Criteria Decision Making in Istanbul from 16 to 21 June 2019 (https://mcdm2019.org/about/). International Society on Multiple Criteria Decision Making (MCDM) brings together academicians, professionals, researchers, students and policymakers at a bi-annual conference since 1975. MCDM 2019
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    The efficiency of nations in the struggle against the COVID-19 pandemic
    (IGI Global, 2022-04-01) Aktas, Emel; Ülengin, Füsun; Topcu, Ilker; Gundes, Eda Helin
    The COVID-19 crisis has caused unprecedented suffering across the world. Millions have become infected, and hundreds of thousands have lost their lives. Nations mobilised their health workers and infrastructure to curb the spread of the disease and cure the infected. This paper aims to investigate the efficiency of nations in their struggle against the COVID-19 and how their efficiency changed over time analysing data from June and December 2020 with a novel three-stage methodology. In the first stage, we clustered 107 nations into highly competitive, competitive, and non-competitive countries using their Global Competitiveness Index scores published by the World Economic Forum evaluate a country in a group of comparable countries. In the second stage, we used Data Envelopment Analysis to assess the efficiency of each nation. In the third stage, we investigated the relationship between countries' efficiency and performance in 66 variables published in the United Nations Human Development Report along with the long-debated aspect of a nation's political governance regime using Tobit regression. Based on the data in June and December, the USA and the UK were the worst performers in the highly competitive nations cluster, Chile and Peru were the worst performers in the competitive nations cluster, and Brazil and Mozambique were the worst performers in the non-competitive nations cluster, respectively. Air pollution, international inbound tourists, urban population significantly reduced while domestic credit and gross national income per capita significantly increased efficiency, but the political regime did not affect efficiency.
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    Traveler satisfaction in rapid rail systems: the case of Istanbul Metro
    (Taylor and Francis, 2017-03-13) Yanik, Seda; Aktas, Emel; Topcu, Ilker
    Multi-faceted characteristics of urban travel have an impact on the passengers' overall satisfaction with the transport system. In this study, we investigate the interrelationships among traveler satisfaction, travel and traveler characteristics, and service performance in a multimodal network that comprises of a trunk line and its feeder lines. We analyze the factors influencing the choices of access to rail transit stations and the satisfaction of transit travelers with the rapid rail transit systems. We quantitatively study these relationships and demonstrate the complexity of evaluating transit service performance. Since the interrelationships among variables affecting this system are mainly stochastic, we analyze the satisfaction with transit system problem using a Bayesian Belief Network (BBN), which helps capture the causality among variables with inherent uncertainty. Using the case of Istanbul, we employ the BBN as a decision support tool for policy makers to analyze the rapid rail transit services and determine policies for improving the quality and the level of service to increase the satisfaction with transit system. In the case study, satisfaction with accessibility and access mode variables are found to be more effective variables than total travel time for travel time satisfaction, confirming the significant role of access in multimodal travels.