İşletme Fakültesi

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Citation Count: 4
An Adaptive Affinity Matrix Optimization for Locality Preserving Projection via Heuristic Methods for Hyperspectral Image Analysis
(IEEE-Inst Electrıcal Electronıcs Engıneers Inc, 2019) Ceylan, Oğuzhan; Ceylan, Oğuzhan
Locality preserving projection (LPP) has been often used as a dimensionality reduction tool for hyperspectral image analysis especially in the context of classification since it provides a projection matrix for embedding test samples to low dimensional space. However, the performance of LPP heavily depends on the optimization of two parameters of the graph affinity matrix: k-nearest neighbor and heat kernel width, when one considers an isotropic kernel. These two parameters might be optimally chosen simply based on a grid search. In case of using a generalized heat kernel where each feature is separately weighted by a kernel width, the number of parameters that need to be optimized is related to the number of features of the dataset, which might not be very easy to tune. Therefore, in this article, we propose to use heuristic methods, including genetic algorithm (GA), harmony search (HS), and particle swarm optimization (PSO), to explore the effects of the heat kernel parameters aiming to analyze the embedding quality of LPP's projection in terms of various aspects, including 1-NN classification accuracy, locality preserving power, and quality of the graph affinity matrix. The results obtained with the experiments on three hyperspectral datasets show that HS performs better than GA and PSO in optimizing the parameters of the affinity matrix, and the generalized heat kernel achieves better performance than the isotropic kernel. Additionally, a feature selection application is performed by using the kernel width of the generalized heat kernel for each heuristic method. The results show that very promising results are obtained in comparison with the state-of-the-art feature selection methods.
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: 6
Alone but together autonomous but related: Self-construal effects on happiness in social experiences
(Wiley, 2018) Merdin-Uygur, Ezgi; Hesapci, Ozlem
Communal tables and open workspaces have become popular servicescapes that is contemporary spaces for experiencing dining or working alone but together. Previous research demonstrates that experiencing with close others (e.g. with friends or family) increases happiness and satisfaction but experiences shared with strangers in contexts such as communal tables or workshops have not yet been thoroughly analyzed. Addressing this research gap from a social-psychological perspective we suggest that even though individuals are generally happier when they share experiences with loved ones self-construal plays a moderating role in the relationship. Individuals with high autonomy and high relatedness do not anticipate greater happiness from experiences shared with friends than with those shared with strangers. Three experimental studies (two online and one field) demonstrate this effect using different operationalizations of autonomy relatedness. Managerial implications are discussed and suggestions are made for future research.
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: 18
Applying a behavioural and operational diagnostic typology of competitive intelligence practice: empirical evidence from the SME sector in Turkey
(Taylor and Francis Group, 2012) Wright, Sheila; Bisson, Christophe; Duffy, Alistair P.
This paper reports on an empirical study conducted within the SME sector in the city of Istanbul Turkey. The findings from this study enabled the creation of a behavioural and operational typology of competitive intelligence practice one developed from the work of S. Wright D.W. Pickton and J. Callow (2002. Competitive intelligence in UK firms: A typology. Marketing Intelligence & Planning 20 349-360). Using responses to questions which indicated a type of behaviour or operational stance towards the various strands of CI practice under review it has been possible to identify areas where improvements could be made to reach an ideal situation which could garner significant competitive advantage for the SMEs surveyed. © 2012 Copyright Taylor and Francis Group LLC.
Citation Count: 5
Art investment: hedging or safe haven through financial crises
(Springer, 2020) Öztürkkal, Belma; Toğan-Eğrican, Aslı
We analyze long-term art auction sales data focusing on and around financial crisis periods with other investment returns to understand whether art can be considered a safe haven during volatile times or a hedging option in general by analyzing art auction data in a volatile emerging market. Our findings suggest Turkish art returns are either negatively correlated or at low correlation with other investments, including the equity market. We have the view that art can be considered a hedging mechanism on average to enhance returns and to decrease the risk of portfolios and improve diversification. However, we do not discard the safe-haven hypothesis, either. Although the auction data on the crisis period is limited, results of and around crisis periods show art returns are positively correlated with various volatility indices. In addition, the number of art transactions also increases after the crisis years, which may be a sign of liquidity requirement of some investors and an opportunity for buyers. The benefit is visible especially during years of contractions, which do not end with a very severe crisis, since the art auction market liquidity dries if the crisis is severe.
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: 20
A behavioral analysis of investor diversification
(Routledge Journals Taylor & Francis Ltd, 2014) Fuertes, Ana-Maria; Muradoğlu, Gülnur; Öztürkkal, Belma
This paper studies the link between individual investors' portfolio diversification levels and various personal traits that proxy informational advantages and overconfidence. The analysis is based on objective data from the largest Turkish brokerage house tracking 59951 individual investors' accounts with a total of 3248654 million transactions over the period 2008-2010. Wealthier highly educated older investors working in the finance sector and those trading relatively often show higher diversification levels possibly because they are better equipped to obtain and process information. Finance professionals married investors and those placing high-volume orders through investment centers show poorer diversification possibly as a reflection of overconfidence. Our analysis reveals important nonlinear effects implying that the marginal impact of overconfidence on diversification is not uniform across investors but varies according to the investor's information gathering and processing abilities.
Citation Count: 11
Behavioral Biases Of Finance Professionals: Turkish Evidence
(Elsevier Science Bv, 2016) Kiymaz, Halil; Öztürkkal, Belma; Akkemik, K. Ali
This study extends the existing literature on the determinants of behavioral biases of Turkish finance sector professionals. It examines the impact of various personal and objective attributes of finance sector professionals on their risk choices derived from their portfolio allocation and personal wealth data. Utilizing survey data from 206 professionals we find that these professionals take higher risk in the form of investment in equities when investing in home country firms (geographic bias) and investing in firms headquartered in their home towns (home bias). Those relying on their own predictions when making investment decisions and those with emotional biases invest less in equities. Findings further show that younger professionals professional with less education with lower risk aversion and with single broker accounts are more likely to invest in equities. We also find that those with higher expected returns invest more in equities showing overconfidence. Subsample analysis results for finance professionals suggest that portfolio managers and brokerage company professionals display differing risk taking behavior. (C) 2016 Elsevier B.V. All rights reserved.
Citation Count: 0
Capital Markets Trade Openness and Productivity in Emerging Economies Introduction
(M.E Sharpe Inc., 2011) Bilgin, Mehmet Hüseyin; Danis, Hakan
[Abstract Not Available]
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: 95
Corporate Social Responsibility and Financial Performance: The Moderating Role of Ownership Concentration in Turkey
(MDPI, 2019) Akben Selçuk, Elif
The objective of this study is to investigate the impact of corporate social responsibility (CSR) engagement on firm financial performance in a developing country, Turkey, and to analyze the moderating role of ownership concentration in the CSR-financial performance relationship. The sample consists of non-financial public firms listed on the Borsa Istanbul (BIST)-100 index and covers the period between 2014 and 2018. Empirical results using an instrumental variable approach show that corporate social responsibility has a positive relationship with financial performance. Furthermore, findings indicate that this relationship is negatively moderated by ownership concentration even when endogeneity is controlled for.
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: 7
Daily and Intraday Herding within Different Types of Investors in Borsa Istanbul
(Routledge Journals, Taylor & Francis Ltd, 2019) Ersan, Oğuz; Ekinci, Cumhur; Ersan, Oğuz
This paper aims to explore the daily and intraday herd behavior of various investor groups trading in an emerging equity market, Borsa Istanbul (BIST). We analyze a one-year tick-by-tick order and trade data of BIST 100 Index stocks and document differences in herding behavior of investor groups considering market capitalization, market conditions, and announcements as well as daily and intraday periodicities. We find that nonprofessional investors (brokerage houses and domestic funds) tend to herd on large (small) stocks; their herding behavior mostly exhibits a U shape (an inverse U shape) during the day. All types of investors tend to herd in down markets on a daily basis while this behavior disappears, even inverts intraday.
Citation Count: 14
Determinants of Saving-Borrowing Decisions and Financial Inclusion in a High Middle Income Country: The Turkish Case
(Routledge Journals Taylor & Francis Ltd, 2016) Davutyan, Nurhan; Öztürkkal, Belma
We use a representative survey of the Turkish household sector and investigate factors impinging on saving-borrowing behavior. We run four probit regressions to elucidate (i) the saving decision (ii) asset choice or portfolio composition for those who save (iii) the bank loan decision and lastly (iv) the formal versus informal borrowing decision. We find income education marital status and region within country strongly correlate with those decisions. We offer some insights regarding the influence of variables like rural to urban migrant status and religious belief on saving and borrowing decisions. We discuss the long-term implications of our findings on the Turkish household savings performance.
Citation Count: 3
Developing a measure for "connectorship" as a component of engaged leadership
(Emerald Group Publishing Ltd, 2016) Dastmalchian, Ali; Rezac, Darcy; Muzyka, Daniel F.; Bayraktar, Seçil; Steinke, Claudia; İmer, Havva Pınar
Purpose - The purpose of this paper is to report the findings of a mixed methods study that explored how active community engaged and connected managers were in their local and broader communities (engaged leadership, EL). The paper specifically investigates an under researched aspect of EL - "connectorship" - with focus on developing a measure for connectorship. The authors present the conceptual framework for EL, followed by the operationalization of "connectorship" construct. Design/methodology/approach - The paper focusses on developing a measure for connectorship using data from a qualitative study of 18 senior managers followed by a survey of 458 managers in Canada. Findings - Content analyses of qualitative data led to the generation of 93 items measuring connectorship. Based on these items, quantitative analyses of survey data from 453 respondents yielded a final measure of connectorship, which consisted of 28 items explored under eight dimensions. Research limitations/implications - An organization's emphasis on connectedness and engagement of leaders will improve knowledge sharing and better mutual understanding of organizational issues among managers. It will also help attain employment stability and decrease hiring and related costs by reducing turnover. Future research, specifically longitudinal studies of leaders at various organizational levels, could incorporate connectorship as a key criterion for leadership effectiveness. Practical implications - The focus on connectorship skills implies that in organizations the emphasis should go beyond traditional leadership skills development and included the neglected connectorship skills development. Increased connectedness and engagement among leaders will have positive performance implications. Social implications - For effective corporate citizenship, the EL framework and a focus on connectorship would help leaders better understand the importance of social networks, be aware of their own network, and improve their skills in connecting the people within their networks. Originality/value - Using a variable centered approach within the framework of EL the paper contributes to leadership literature by conceptually defining connectorship developing a measure for this construct and testing its psychometric properties.
Citation Count: 0
Diffusion of Pure and Hybrid Forms of a Practice: Language of Instruction in Turkish Universities, 1983-2014
(Wiley Periodicals, Inc, 2020) Topaler, Başak; Üsdiken, Behlül
It is well recognized in the literature that practice variation is an integral part of diffusion processes. What remains less explored is the emergence of distinct forms of a novel practice and the interdependencies in their diffusion. In this study, we make a distinction between the pure version of a practice and ensuing hybrid variants and investigate how diffusion processes unfold for these alternative practice forms. Our empirical investigation in the Turkish higher education field demonstrates that hybrid practice forms became viable alternatives to the pure version of instruction in English and diffused in an interdependent manner. Further, diffusion of pure and hybrid forms was uneven across private and public universities. Our study contributes to the diffusion and practice variety literature as we establish that multiple versions of a practice that diffuse concurrently in a field may be building on or hampering each other, and they may diffuse in fragmented ways across different sub-populations.
Citation Count: 7
Dissidents with an innovation cause? Non-institutionalized actors' online social knowledge sharing solution-finding tensions and technology management innovation
(Emerald Group Publishing Limited, 2015) De Kervenoael, Ronan; Bisson, Christophe; Palmer, Mark
Purpose - Traditionally most studies focus on institutionalized management-driven actors to understand technology management innovation. The purpose of this paper is to argue that there is a need for research to study the nature and role of dissident non-institutionalized actors' (i.e. outsourced web designers and rapid application software developers). The authors propose that through online social knowledge sharing non-institutionalized actors' solution-finding tensions enable technology management innovation. Design/methodology/approach - A synthesis of the literature and an analysis of the data (21 interviews) provided insights in three areas of solution-finding tensions enabling management innovation. The authors frame the analysis on the peripherally deviant work and the nature of the ways that dissident non-institutionalized actors deviate from their clients (understood as the firm) original contracted objectives. Findings - The findings provide insights into the productive role of solution-finding tensions in enabling opportunities for management service innovation. Furthermore deviant practices that leverage non-institutionalized actors' online social knowledge to fulfill customers' requirements are not interpreted negatively but as a positive willingness to proactively explore alternative paths. Research limitations/implications - The findings demonstrate the importance of dissident non-institutionalized actors in technology management innovation. However this work is based on a single country (USA) and additional research is needed to validate and generalize the findings in other cultural and institutional settings. Originality/value - This paper provides new insights into the perceptions of dissident non-institutionalized actors in the practice of IT managerial decision making. The work departs from but also extends the previous literature demonstrating that peripherally deviant work in solution-finding practice creates tensions enabling management innovation between IT providers and users.
Citation Count: 8
Does mood affect institutional herding?
(Elsevier, 2020) Gavriilidis, Konstantinos; Kallinterakis, Vasileios; Öztürkkal, Belma
Drawing on a unique data set of daily portfolio holdings for Turkish mutual funds we investigate the relationship between mood and institutional herding on the premises of various established mood proxies (weekend effect; holiday effect; Ramadan; sunshine). Results indicate that fund managers in Turkey herd significantly, with their herding growing in magnitude as the number of active funds per stock rises and appearing stronger on the buy-than the sell-side. Although the relationship of mood with institutional herding occasionally assumes the correct sign as per theoretical expectations, institutional herding is found to be insignificantly different across various mood states, thus denoting that mood does not impact the propensity of fund managers to herd. (C) 2020 Elsevier B.V. All rights reserved.

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