İşletme Fakültesi

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Citation Count: 13
Adoption of Mobile Health Apps in Dietetic Practice: Case Study of Diyetkolik
(Jmır Publıcatıons, Inc, 130 Queens Quay E, 2020) Aydın, Mehmet Nafiz; Aydın, Mehmet Nafiz; Akdur, Gizdem
Background: Dietetics mobile health apps provide lifestyle tracking and support on demand. Mobile health has become a new trend for health service providers through which they have been shifting their services from clinical consultations to online apps. These apps usually offer basic features at no cost and charge a premium for advanced features. Although diet apps are now more common and have a larger user base, in general, there is a gap in literature addressing why users intend to use diet apps. We used Diyetkolik, Turkey's most widely used online dietetics platform for 7 years, as a case study to understand the behavioral intentions of users. Objective: The aim of this study was to investigate the factors that influence the behavioral intentions of users to adopt and use mobile health apps. We used the Technology Acceptance Model and extended it by exploring other factors such as price-value, perceived risk, and trust factors in order to assess the technology acceptance of users. Methods: We conducted quantitative research on the Diyetkolik app users by using random sampling. Valid data samples gathered from 658 app users were analyzed statistically by applying structural equation modeling. Results: Statistical findings suggested that perceived usefulness (P<.001), perceived ease of use (P<.001), trust (P<.001), and price-value (P<.001) had significant relationships with behavioral intention to use. However, no relationship between perceived risk and behavioral intention was found (P=.99). Additionally, there was no statistical significance for age (P=.09), gender (P=.98), or previous app use experience (P=.14) on the intention to use the app. Conclusions: This research is an invaluable addition to Technology Acceptance Model literature. The results indicated that 2 external factors (trust and price-value) in addition to Technology Acceptance Model factors showed statistical relevance with behavioral intention to use and improved our understanding of user acceptance of a mobile health app. The third external factor (perceived risk) did not show any statistical relevance regarding behavioral intention to use. Most users of the Diyetkolik dietetics app were hesitant in purchasing dietitian services online. Users should be frequently reassured about the security of the platform and the authenticity of the platform's dietitians to ensure that users' interactions with the dietitians are based on trust for the platform and the brand.
Citation Count: 24
Antecedents and performance outcomes of value-based selling in sales teams: a multilevel, systems theory of motivation perspective
(Springer, 2020) Mengüç, Bülent; Mengüç, Bülent; Panagopoulos, Nikolaos G.
Firms are increasingly deploying a value-based selling (VBS) approach in their sales organizations to drive growth for new offerings. However, VBS adoption remains challenging, signaling that leaders need guidance to motivate VBS. Drawing from the systems theory of motivation, we examine motivational mechanisms at two levels-salesperson and sales team-to understand how to motivate, and benefit from, VBS. Using multisource data (i.e., salespeople, managers, archival performance) from 70 sales teams in a U.S.-based manufacturing and services provider, our findings illustrate drivers and outcomes of VBS. Specifically, we uncover a framework of salesperson, leader, customer, and team factors that help explain salesperson motivation for VBS. Importantly, we link VBS to customers' adoption of new products to support VBS's role for selling new products. Critical for sales team strategy, our model also integrates a team-level motivational mechanism to provide a comprehensive framework for salesperson and sales team motivations and outcomes.
Citation Count: 11
Assessment of chromite liberation spectrum on microscopic images by means of a supervised image classification
(Elsevier Science Bv, 2017) Çavur, Mahmut; Çavur, Mahmut; Hosten, Cetin
Assessment of mineral liberation spectrum with all its aspects is essential for plant control and optimization. This paper aims to estimate 2D mineral map and its associated liberation spectrum of a particular chromite sample from optical micrographs by using Random Forest Classification a powerful machine-learning algorithm implemented on a user-friendly and an open-source software. This supervised classification method can be used to accurately generate 2D mineral map of this chromite sample. The variation of the measured spectra with the sample size is studied showing that images of 200 particles randomly selected from the optical micrographs are sufficient to reproduce liberation spectrum of this sample. In addition the 2D spectrum obtained with this classification method is compared with the one obtained from the Mineral Liberation Analyzer (MLA). Although 2D mineralogical compositions obtained by the two methods are quite similar microscopic analysis estimates poorer liberation than MLA due to the residual noise (misclassified gangue) generated by the classification. Nevertheless we cannot compare the reliabilities of the two methods as there is not a standard produce yet to quantify the accuracy of MLA analysis. (C) 2017 Elsevier B.V. All rights reserved.
Citation Count: 0
Babbling through social media: A cross-country study mapping out social networks using eWOM intentions
(Springer, 2023) Zülal, İşler; Kıygı-Çallı, Meltem; El Oraiby, Maryam
This research aims to determine the factors affecting the users’ electronic word-of-mouth (eWOM) seeking and sharing intentions and to reveal the interactions among and within clusters using social network analysis (SNA). This study includes three hierarchical sub-studies conducted in two countries, Turkey and Poland. First, we develop a segmentation for social networking site (SNS) users based on the frequency of sharing product-related information on SNSs. Second, we investigate the impact of several factors that affect eWOM seeking and sharing intentions using regression analysis. In the second sub-study, we also include the identified segments developed in the first sub-study as another factor that may have differentiated eWOM intentions. Third, to understand the degree of interaction among SNS users, we apply an SNA using the forecasted eWOM intentions scores from the second sub-study, which gives us hypothetical social networks. The results of SNA present strong interactions inter- and intra-clusters in both countries. Some key findings include the identification of three SNS user segments, including “Middlers,” that may be of particular interest to brands. We also find that in terms of eWOM intentions, users in Turkey are more active than in Poland. Although some predictors of eWOM seeking and sharing intentions differ between the two countries, users intend to be more active in eWOM seeking than in eWOM sharing. The comparative study provides valuable insights for decision-makers to engage different market segments via SNSs with various proposed features using suggested information contents for selected product categories.
Citation Count: 29
Bank credit in uncertain times: Islamic vs. conventional banks
(Elsevier Ltd, 2020) Bilgin, Mehmet Hüseyin; Danışman, Gamze Öztürk; Demir, Ender; Tarazi, Amine
This paper explores whether the impact of economic uncertainty on credit growth differs for Islamic vs. conventional banks. Using a sample of 416 banks (58 Islamic and 358 conventional) in 12 countries, the findings indicate that an increase in economic uncertainty significantly decreases the credit growth of conventional banks but does not have any significant impact on Islamic banks’ credit growth. Our results are robust to alternative specifications and addressing endogeneity concerns using GMM estimators. We further observe that our findings are stronger for the following countries: (1) countries with explicit deposit insurance protection system for Islamic banks, (2) lower foreign dominance, and (3) countries with a higher share of deposits and assets in Islamic banks.
Citation Count: 11
Bivariate Pseudo-Gompertz distribution and concomitants of its order statistics
(Elsevier Science Bv, 2013) Gebizlioğlu, Ömer Lütfi; Gebizlioğlu, Ömer Lütfi
This paper presents a new bivariate Pseudo-Gompertz distribution that sprouts from the classical Gompertz distribution and possesses the features of pseudo-distribution functions. In addition to some standard properties of the proposed distribution distributions of order statistics and their concomitants for samples drawn from the new distribution are obtained. The survival and hazard functions of the concomitants are shown and their values are tabled. Interpretations of the results are given in connection with risk events and risk management. (C) 2013 Elsevier B.V. All rights reserved.
Citation Count: 4
Computing finite time non-ruin probability and some joint distributions in discrete time risk model with exchangeable claim occurrences
(Elsevier Science, 2017) Gebizlioğlu, Ömer Lütfi; Gebizlioğlu, Ömer Lütfi
In this paper we study a discrete time risk model based on exchangeable dependent claim occurrences. In particular we obtain expressions for the finite time non-ruin probability and the joint distribution of the time to ruin the surplus immediately before ruin and the deficit at ruin. An illustration of the results is given and some implications of the results are provided. Comparisons are made with the corresponding results for the classical compound binomial model of independent and identically distributed claim occurrences. (C) 2016 Elsevier E.V. All rights reserved.
Citation Count: 97
Coordinated Electric Vehicle Charging With Reactive Power Support to Distribution Grids
(IEEE, 2019) Ceylan, Oğuzhan; Bharati, Guna R.; Paudyal, Sumit; Ceylan, Oğuzhan; Bhattarai, Bishnu P.; Myers, Kurt S.
We develop hierarchical coordination frameworks to optimally manage active and reactive power dispatch of number of spatially distributed electric vehicles (EVs) incorporating distribution grid level constraints. The frameworks consist of detailed mathematical models which can benefit the operation of both entities involved i.e. the grid operations and EV charging. The first model comprises of a comprehensive optimal power flow model at the distribution grid level while the second model represents detailed optimal EV charging with reactive power support to the grid. We demonstrate benefits of coordinated dispatch of active and reactive power from EVs using a 33-node distribution feeder with large number of EVs (more than 5000). Case studies demonstrate that in constrained distribution grids coordinated charging reduces the average cost of EV charging if the charging takes place at nonunity power factor mode compared to unity power factor. Similarly the results also demonstrate that distribution grids can accommodate charging of increased number of EVs if EV charging takes place at nonunity power factor mode compared to unity power factor.
Citation Count: 19
Customer Participation Variation and Its Impact on Customer Service Performance: Underlying Process and Boundary Condition
(Sage Publications, 2020) Mengüç, Bülent; Auh, Seigyoung; Wang, Fatima
Drawing on the customer participation (CP) literature, this research proposes that CP variation is the degree to which employees perceive variability across customers with regard to customers sharing information, time, and effort and making suggestions to enhance the service delivery process and outcome. Drawing on the job demands-resources model, this research explicates the mediating process by which CP variation affects customer service performance and its boundary conditions. Study 1 uses data from a field study in the banking industry to show that CP variation negatively influences customer service performance through greater customer-related burnout. The authors show that this mediation process is moderated by contingencies that mitigate or exacerbate the indirect relationship. Study 2 further validates the CP variation construct by testing for discriminant validity against similar and related constructs, such as CP quality, in more diverse service industries (insurance, legal consulting, travel and tourism, health care, and physical fitness). Finally, an examination of the moderating role of CP quality provides a more nuanced picture of the intricacies between CP variation and CP quality. This article concludes with a discussion of the theoretical and practical implications for CP variation research.
Citation Count: 2
Double branch outage modeling and simulation: Bounded network approach
(Elsevier Science, 2015) Dağ, Hasan; Ceylan, Oğuzhan; Dağ, Hasan
Energy management system operators perform regular outage simulations in order to ensure secure operation of power systems. AC power flow based outage simulations are not preferred because of insufficient computational speed. Hence several outage models and computational methods providing acceptable accuracy have been developed. On the other hand double branch outages are critical rare events which can result in cascading outages and system collapse. This paper presents a double branch outage model and formulation of the phenomena as a constrained optimization problem. Optimization problem is then solved by using differential evolution method and particle swarm optimization algorithm. The proposed algorithm is applied to IEEE test systems. Computational accuracies of differential evolution based solutions and particle swarm optimization based solutions are discussed for IEEE 30 Bus Test System and IEEE 118 Bus Test System applications. IEEE 14 Bus Test System IEEE 30 Bus Test System IEEE 57 Bus Test System IEEE 118 Bus Test System and IEEE 300 Bus Test System simulation results are compared to AC load flows in terms of computational speed. Finally the performance of the proposed method is analyzed for different outage configurations. (C) 2015 Elsevier Ltd. All rights reserved.
Citation Count: 10
Dynamic network analysis of online interactive platform
(Springer, 2019) Aydın, Mehmet Nafiz; Perdahci, N. Ziya
The widespread use of online interactive platforms including social networking applications community support applications draw the attention of academics and businesses. The basic trust of this research is that the very nature of these platforms can be best described as a network of entangled interactions. We agree with scholars that these platforms and features necessitate the call for theory of network as a novel approach to better understand their underpinnings. We examine one of the leading online interactive health networks in Europe. We demonstrate that the interactive platform examined exhibits essential structural properties that characterize most real networks. In particular we focus on the largest connected component so-called a giant component (GC) to better understand network formation. Dynamic network analysis helps us to observe how the GC has evolved over time and to identify a particular pattern towards emerging a GC. We suggest that the network measures examined for the platform should be considered as novel and complementary metrics to those used in conventional web and social analytics. We argue that various stages of GC development can be a promising indicator of the strength and endurance of the interactions on the platform. Platform managers may take into account basic stages of the emergence of the GC to determine varying degrees of product attractiveness.
Citation Count: 44
Economic Policy Uncertainty And Bank Credit Growth: Evidence From European Banks
(Elsevier B.V., 2020) Ersan, Oğuz; Ersan, Oğuz; Demir, Ender
Using a sample of 2977 private and listed banks in the EU-5 countries (the United Kingdom, Germany, Spain, Italy, France) for the years 2009–2018, this paper explores the impact of Economic Policy Uncertainty (EPU) on credit growth. Using panel data fixed effects methodology and controlling for endogeneity using two-step difference GMM estimators, our findings indicate that uncertainty in economic policies hampers the credit growth of European banks. Our bank type-based analyses indicate that the effect is mainly valid for cooperative banks. Additional analyses imply that the negative impact of EPU on credit growth is more pronounced in civil law countries, increases with debt maturity, and weakens for banks with a larger number of employees and branches. Furthermore, the unfavorable effects are stronger in well-capitalized banks, banks with foreign subsidiaries, and banks with a higher share of wholesale funding. We also provide several policy implications for different economic actors.
Citation Count: 62
Economic policy uncertainty, stakeholder engagement, and environmental, social, and governance practices: The moderating effect of competition
(Wiley, 2020) Vural-Yavaş, Çiğdem
his paper investigates the effect of the economic policy uncertainty (EPU) on corporate environmental, social, and governance practices (ESG), using 6,562 firm-year observations from 15 developed European countries covering the period from 2004 to 2017. The results show that during periods of high uncertainty, firms increase their overall ESG performance, corporate environmental performance, and performance in governance. The relationship is valid for emission, resource use, workforce, management, and corporate social responsibility (CSR) strategy subdimensions of ESG. Furthermore, during periods of high uncertainty, firms operating in concentrated industries increase their overall ESG activities and corporate environmental performance. These results suggest that firms use ESG practices as risk-reducing activities like insurance, during high periods of uncertainty. Overall, consistent with the stakeholder theory, the results indicate that firms increase their ESG practices not only to reduce corporate risk-taking but also to follow value-increasing activities during periods of high uncertainty, implying an improved stakeholder engagement.
Citation Count: 49
The effect of European and global uncertainty on stock returns of travel and leisure companies
(Sage Publications Ltd, 2019) Ersan, Oğuz; Akron, Sagi; Demir, Ender
This article aims to evaluate the impact of economic policy uncertainty (EPU) on the STOXX Europe 600 Travel & Leisure Price Index by utilizing a monthly data set for 20 years through 1997-2016. It is found that both the European and the global EPU have significant negative effects on the stock returns of travel and leisure companies. We demonstrate the significantly superior forecasting power of EPU measures on tourism and leisure stock returns relative to a rather weak forecasting power of various macroeconomic variables.
Citation Count: 21
Efficiency analysis of emergency departments in metropolitan areas
(Elsevier, 2020) Uray, Nimet; Karadayı, Melis Almula; Ekinci, Yeliz; Ulengin, Füsun; Uray, Nimet; Karaosmanoğlu, Elif
The demand in the healthcare industry is increasing exponentially due to aging population of the world and this is leading to a rapid increase in the cost of healthcare. The emergency departments of the hospitals are the frontline of health care systems and play an additional critical role in providing an efficient and high-quality response for patients. The overcrowding at the emergency departments due to growing demand results in a situation where the demand for ED services exceeds the ability to provide care in a reasonable amount of time. This has led countries to reconsider their health policies in a way to increase their efficiency in their healthcare systems in general and in emergency departments, in particular. As in many countries, there has been a steady and significant increase in the number of patients that seek health services at the emergency departments of state hospitals of Turkey, due to the significant structural reforms in health services since 2003. While meeting this increasing demand, it is ever more important to provide these critical health services efficiently. Therefore, the efficiency of the emergency departments of seven general hospitals run by Istanbul's Beyoglu State Hospitals Association have been analyzed using categorical Data Envelopment Analysis (DEA) models. The analysis of DEA results is supported by a set of statistical methods to make it easier for the hospital administrators to interpret the analysis and draw conclusions. The analysis shows that less-equipped EDs are supported by better equipped, larger EDs, resulting in a hub-and-spoke type of structure among the EDs where "satellite" EDs serve an important referral function and thus evaluating their efficiency without taking the interoperability among these units into account would not be an accurate assessment of their performance.
Citation Count: 13
Empirical Evidence of Revenue Management in the Cruise Line Industry
(Sage Publications Inc, 2019) Ayvaz Çavdaroğlu, Nur; Gauri, Dinesh K.; Webster, Scott
Revenue management (RM) has received considerable attention from both academic and business professionals. It encompasses several techniques regarding capacity allocation pricing and resource management of fixed time-sensitive capacity. RM can be roughly divided into two categories defined by the control mechanism that increases revenue: capacity allocation or price optimization. Our work falls in the latter category. In our model we allow for partial substitutability among products (e.g. a customer making a purchase decision may consider multiple alternatives-different departure dates different destinations different cabin types). We also include marketing expense in addition to prices as a lever for increasing revenue. These features are relevant to dynamic pricing in practice. The method is illustrated with booking data from a cruise company yielding optimal advertising and prices for 300 products. The application of the model results in an increase in revenue in the range of 8%-20%.
Citation Count: 68
Forecasting electricity demand for Turkey: Modeling periodic variations and demand segregation
(Elsevier, 2017) Bilge, Ayşe Hümeyra; Yücekaya, Ahmet; Bilge, Ayşe Hümeyra
In deregulated electricity markets the independent system operator (ISO) oversees the power system and manages the supply and demand balancing process. In a typical day the ISO announces the electricity demand forecast for the next day and gives participants an option to prepare offers to meet the demand. In order to have a reliable power system and successful market operation it is crucial to estimate the electricity demand accurately. In this paper we develop an hourly demand forecasting method on annual weekly and daily horizons using a linear model that takes into account the harmonics of these variations and the modulation of diurnal periodic variations by seasonal variations. The electricity demand exhibits cyclic behavior with different seasonal characteristics. Our model is based solely on sinusoidal variations and predicts hourly variations without using any climatic or econometric information. The method is applied to the Turkish power market on data for the period 2012-2014 and predicts the demand over daily and weekly horizons within a 3% error margin in the Mean Absolute Percentage Error (MAPE) norm. We also discuss the week day/weekend/holiday consumption profiles to infer the proportion of industrial and domestic electricity consumption. (C) 2017 Elsevier Ltd. All rights reserved.
Citation Count: 19
Frontline Employee Feedback-Seeking Behavior: How Is It Formed and When Does It Matter?
(Sage Publications Inc, 2019) Mengüç, Bülent; Mengüç, Bülent; İmer, Havva Pınar; Uslu, Aypar
This research comprises two studies that extend the literature on the proactive behavior of feedback seeking. Study 1 uses cross-sectional data from frontline employees across 51 apparel stores to examine how feedback seeking is formed and under what conditions. The results suggest that the development of feedback-seeking behavior is contingent on a feedback-seeking climate and the relationship between an employee and his or her supervisor. Study 2 uses longitudinal data collected across three time periods from multiple respondents (i.e. frontline employees and managers) not only to replicate the findings from Study 1 but also to explore when feedback seeking matters. The findings reveal that managers should target employees who are less (vs. more) satisfied with their jobs because such employees perceive more instrumental value from feedback as a means to improve customer service and sales performance. The findings from this research provide insights that managers can use to increase feedback-seeking behavior from employees and effectively identify and manage the conditions under which feedback seeking will occur to greater or lesser degrees.
Citation Count: 3
Information cascades, short-selling constraints, and herding in equity markets
(Borsa İstanbul Anonim Şirketi, 2020) Tiniç, Murat; Iqbal, Muhammad Sabeeh; Mahmud, Syed F.
This paper examines the relationship between informed trading and herding in Borsa İstanbul. Our firm-level cross-sectional analysis asserts that informed trading can significantly increase future herding levels. Furthermore, we show that the relationship between informed trading and herding intensifies under short-selling restrictions. Our results confirm the predictions of the informational cascades framework where the individuals disregard their private information to follow others. We show that information cascades are relevant both for buy-side herding and sell-side herding. Short-selling restrictions may reinforce the herding behaviour since informed investors may not be able to clear out potential price misalignments.
Citation Count: 8
An inverse coefficient problem for a quasilinear parabolic equation with periodic boundary and integral overdetermination condition
(Wiley-Blackwell, 2015) Bağlan, İrem Sakınç; Kanca, Fatma
In this paper the inverse problem of finding the time-dependent coefficient of heat capacity together with the solution periodic boundary and integral overdetermination conditions is considered. Under some natural regularity and consistency conditions on the input data the existence uniqueness and continuous dependence upon the data of the solution are shown. Some considerations on the numerical solution for this inverse problem are presented with an example. Copyright (c) 2014 John Wiley & Sons Ltd.

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