Faculty of Business

Permanent URI for this communityhttps://hdl.handle.net/10679/4

Browse

Now showing 1 - 20 of 84

Open Access
Adaptive pairs trading strategy performance in Turkish derivatives exchange with the companies listed on Istanbul stock exchange
(Springer International Publishing, 2012-03-02) Bolgün, K. E.; Kurun, E.; Güven, Serhat; Güven, Serhat
We implemented model-driven statistical arbitrage strategies in Turkish equities market. Trading signals are generated by optimized parameters of distance method. When the trade in signal is triggered by the model, market-neutral portfolio is created by long in the synthetic ETF, which is based on constrained least squares regression of selected Istanbul Stock Exchange stocks and short in Turkish Derivatives Exchange (Turkdex) index futures contract. We performed pairs trading strategy based on a comparative mean reversion of asset prices with daily data over the period February 2005 through July 2011 in Istanbul Stock Exchange (ISE) and Turkdex. We constructed a hypothetical ISE30 ETF Index on a daily basis in order to originate pairs trading strategy with Turkdex. Because of the leverage rule of (1–10) index futures contracts, we had to evaluate spot stock pairs formation with futures contracts pairs strategy. The results indicate that applied pairs strategy produced overall returns of 901 per cent during the investment period, whereas naive strategy (buy and hold ISE-30 index) return for the same period was 111 per cent. Similar outperformance was observed in the Sharpe and Sortino ratios.
Open Access
Ambulance location for maximum survival
(Wiley, 2008-02) Erkut, Erhan; Ingolfsson, A.; Erdoğan, G.; Business Administration; ERKUT, Erhan
This article proposes new location models for emergency medical service stations. The models are generated by incorporating a survival function into existing covering models. A survival function is a monotonically decreasing function of the response time of an emergency medical service (EMS) vehicle to a patient that returns the probability of survival for the patient. The survival function allows for the calculation of tangible outcome measures—the expected number of survivors in case of cardiac arrests. The survival-maximizing location models are better suited for EMS location than the covering models which do not adequately differentiate between consequences of different response times. We demonstrate empirically the superiority of the survival-maximizing models using data from the Edmonton EMS system.
Open Access
Assessing consequences of component sharing across brands in the vertical product line in the automotive market
(Wiley, 2012-07) Verhoef, P. C.; Pauwels, Koen Hendrik; Tuk, M. A.; Business Administration; PAUWELS, Koen Hendrik
Component sharing may look great in the boardroom, but not in the showroom. Indeed, savings on R&D and production costs could be offset by a plunge in customer brand attractiveness. Combining experimental with econometric studies, this paper investigates the impact of component sharing on customer evaluation of luxury, volume and economy brands offered in a car manufacturer’s vertical product line. An experimental study shows that the evaluation of luxury brands sharing with a volume brand suffers more than when a volume brand shares components with an economy brand. The evaluation of an economy brand benefits more from sharing with a volume brand than a volume brand suffers from sharing with an economy brand. The magnitude of these effects depends on several factors, such as component type, the source of the component sharing and the salience of component sharing to the consumers. The explorative examination of market share effects confirms that luxury brands may suffer, while economy brands may benefit from component sharing. The first to look at the consumer impact of component sharing, this paper sets up a rich agenda for future research.
Open Access
The asymmetric impact of oil prices, interest rates and oil price uncertainty on unemployment in the US
(Elsevier, 2020-02-01) Kocaaslan, B.; Soytas, U.; Soytaş, Mehmet Ali; Economics; SOYTAŞ, Mehmet Ali
In this study, we investigate the presence of asymmetric interactions between oil prices, oil price uncertainty, interest rates, and unemployment in a cointegration framework. Utilizing the nonlinear auto-regressive distributed lag (NARDL) approach, we show the asymmetric responses of unemployment to changes in oil prices, oil price uncertainty and interest rates in the long-run. More specifically, the results of our analyses suggest that an increase in oil price results in increased unemployment while there is no significant impact of reduced oil prices. On the one hand, reduced oil price uncertainty leads to a decrease in unemployment whereas an increase in oil price uncertainty does not have an impact. We also observe increased unemployment in response to a decrease in interest rates as the impact of increased interest rates is not significant. Last but not least, we find that option-implied oil price volatility, as a measure of oil price uncertainty, outperforms the conditional volatility of crude oil prices in predicting unemployment. This study provides valuable implications for policymakers to design sound economic policies.
Open Access
Being a woman entrepreneur in Turkey: Life role expectations and entrepreneurial self-efficacy
(Sage, 2019-05) Fiş, Ahmet Murat; Ozturkcan, S.; Gür, Faik; Entrepreneurship; International Relations; FİŞ, Ahmet Murat; GÜR, Faik
Two major competing life roles, work and family, are reported to dominate people's efforts in constructing a life. Here, we aim to explore whether and how attributed life roles and related coping strategies of current and aspiring women entrepreneurs meaningfully differentiate and whether the existence of entrepreneurs in their families affects the formation of these different clusters. In our empirical, two-part exploratory study conducted in the emerging economy setting of Turkey, first, we utilize the survey results of 234 women entrepreneurs to explore the issue, and then in the second part of the study, we administer face-to-face interviews to draw out some critical insights. We end up with three different clusters differentiating in their responses to challenges and effect of these on their entrepreneurial self-efficacy beliefs. We believe our study may shed some light on understanding nonhomogeneous women response to roles and challenges in the society and women's entrepreneurial journey.
Open Access
Big data–enabled sign prediction for Borsa Istanbul intraday equity prices
(Elsevier, 2023-12) Kılıç, A.; Güloğlu, B.; Yalçın, Atakan; Üstündağ, A.; International Finance; YALÇIN, Atakan
This paper employs a big data source, the Borsa Istanbul's “data analytics” information, to predict 5-min up, down, and steady signs drawn from closing price changes. Seven machine learning algorithms are compared with 2018 data for the entire year. Success levels for each method are reported for 26 liquid stocks in terms of macro-averaged F-measures. For the 5-min lagged data, nine equities are found to be statistically predictable. For lagged data over longer periods, equities remain predictable, decreasing gradually to zero as the markets absorb the data over time. Furthermore, economic gains for the nine equities are analyzed with algorithms where short selling is allowed or not allowed depending on these predictions. Four equities are found to yield more economic gains via machine learning–supported trading strategies than the equities' own price performances. Under the “efficient market hypothesis,” the results imply a lack of “semistrong-form efficiency.”
Open Access
Bringing sustainability to the heart of a university through teaching, research and service
(EDP Sciences, 2018) Gençtürk, Esra; Mengüç, Mustafa Pınar; Business Administration; Mechanical Engineering; MENGÜÇ, Mustafa Pınar; GENÇTÜRK, Feride Esra
In this short paper, we summarize our targeted efforts at Ozyegin University in Istanbul, Turkey for establishing a sustainable research, teaching and learning environment. The University is striving to have highest level impact on sustainable education, energy, architecture, built environment, business and life-long learning practices. The strategic plan of the University puts the principles of sustainability at the cornerstone of its efforts, with the aim to aspire not only our students and staff, but also the community at large.
Open Access
Building with bricks and mortar: the revenue impact of opening physical stores in a multichannel environment
(Elsevier, 2015-06) Pauwels, Koen Hendrik; Neslin, S. A; Business Administration; PAUWELS, Koen Hendrik
A crucial decision firms face today is which channels they should make available to customers for transactions. We assess the revenue impact of adding bricks-and-mortar stores to a firm's already existing repertoire of catalog and Internet channels. We decompose the revenue impact into customer acquisition, frequency of orders, returns, and exchanges, and size of orders, returns, and exchanges. We use a multivariate baseline method to assess the impact of adding the physical store channel on these revenue components. As hypothesized, store introduction cannibalizes catalog sales and has much less impact on Internet sales. Also as hypothesized, returns and exchanges increase. Interestingly, transaction sizes of purchases, returns, and exchanges do not change. The “availability effect” produces a net increase in purchase frequency across channels. This more than compensates for increased returns, producing a net increase in revenues of 20% by adding the store channel. Our findings yield a deeper understanding of the revenue relation between channels, and of the dynamic cross-channel effects of marketing actions.
Open Access
Captain or deckhand? The impact of self-leadership on employees’ work role performance under remote work
(Frontiers Media, 2022-11-25) Maden-Eyiusta, Ceyda; Alparslan, S. E.; Entrepreneurship; EYİUSTA, Ceyda Maden
Relying on self-determination theory, this study investigates the mediating role of psychological empowerment in the relationship between self-leadership and work role performance (task proficiency, task adaptivity, and task proactivity) in remote work settings. It also explores whether and how supervisor close monitoring moderates the indirect impact of self-leadership on work role performance. Hypotheses were tested using a two-study design including white-collar employees from a broad range of jobs and companies (Study 1) and employee-supervisor dyads working in small and medium-sized firms (Study 2) in Turkey. In Study 1, results showed that self-leadership had a positive indirect effect on employees’ work role performance through psychological empowerment. In Study 2, the cross-lagged two-wave design provided support for this indirect effect while demonstrating partial support for the moderating role of supervisor close monitoring. The current study contributes to research on self-leadership and work role performance by providing a detailed understanding of the motivational process through which self-leadership leads to increased work role performance. It also offers practical insights for enhancing self-leaders’ work role performance, particularly within the remote work context.
Metadata only
Captive diffusions and their applications to order-preserving dynamics
(Royal Society Publishing, 2020-09-30) Mengütürk, L. A.; Mengütürk, Murat Cahit; Business Administration; MENGÜTÜRK, Murat Cahit
We propose a class of stochastic processes that we call captive diffusions, which evolve within measurable pairs of cadlag bounded functions that admit bounded right-derivatives at points where they are continuous. In full generality, such processes allow reflection and absorption dynamics at their boundaries-possibly in a hybrid manner over non-overlapping time periods-and if they are martingales, continuous boundaries are necessarily monotonic. We employ multi-dimensional captive diffusions equipped with a totally ordered set of boundaries to model random processes that preserve an initially determined rank. We run numerical simulations on several examples governed by different drift and diffusion coefficients. Applications include interacting particle systems, random matrix theory, epidemic modelling and stochastic control.
Open Access
Captive jump processes for bounded random systems with discontinuous dynamics
(Elsevier, 2024-01) Macrina, A.; Mengütürk, L. A.; Mengütürk, Murat Cahit; Business Administration; MENGÜTÜRK, Murat Cahit
Stochastic captive jump processes are explicitly constructed in continuous time, whose non-linear dynamics are strictly confined by bounded domains that can be time-dependent. By introducing non-anticipative path-dependency, the framework offers the possibility of generating multiple inner tunnels within a master domain, such that a captive jump process is allowed to proceed either within a single inner tunnel or jump in between tunnels without ever penetrating the outermost shell. If a captive jump process is a continuous martingale or a pure-jump process, the uppermost confining boundary is non-decreasing, and the lowermost confining boundary is non-increasing. Under certain conditions, it can be shown that captive jump processes are invariant under monotonic transformations, enabling one to construct and study systems of increasing complexity using simpler building blocks. Amongst many applications, captive jump processes may be considered to model phenomena such as electrons transitioning from one orbit (valence shell) to another, quantum tunnelling where stochastic wave-functions can “penetrate” inner boundaries (i.e., walls) of potential energy, non-linear dynamical systems involving multiple attractors, and sticky concentration behaviour of pathogens in epidemics. We provide concrete, worked-out examples, and numerical simulations for the dynamics of captive jump processes within different geometries as demonstrations.
Open Access
Çevri̇mi̇çi̇ ve geleneksel: youtube ve televi̇zyon reklamlarına yöneli̇k tüketi̇ci̇ algılarının karşılaştırılması
(Pazarlama ve Pazarlama Araştırmaları Derneği, 2018) Köz, Zeynep; Atakan, Şükriye Sinem; Business Administration; ATAKAN, Şükriye Sinem; Köz, Zeynep
Bu araştırma, tüketicilerin YouTube ve televizyon reklamlarına yönelik tutumlarını incelemekte ve karşılaştırmaktadır. On iki tüketiciden veri toplamak için, kalitatif bir araştırma yöntemi olan ve derinlemesine görüşme tekniğini projektif tekniklerle birleştiren Zaltman Metafor Çıkarım Tekniği (ZMET) kullanılmıştır. Analiz, tüketicilerin YouTube reklamlarını televizyon reklamlarından daha enerjik, yenilikçi ve genç olarak algıladıklarını göstermektedir. YouTube reklamlarının tersine, televizyon reklamları yaşlı, klasik, rahatsız edici ve yapay olarak tasvir edilmektedir. Her ne kadar, tüketiciler açısından YouTube ve televizyon reklam içerikleri farklılaşmasa da, YouTube platformunun sunum avantajları (örn. yüksek kontrol imkanı, etkileşim özelliği, renkler, arka plan) YouTube reklam algısını pozitif olarak etkilemektedir. Elde edilen sonuçlar gösteriyor ki, reklam platformlarından bağımsız olarak, mizahi ve eğlendirici bir şekilde sunulan, gerçekçi, bilgi veren, izlenilen video ya da dizi içeriğine uygun reklam içerikleri tüketicilerin dikkatini çekmektedir.
Open Access
Client-server versus peer-to-peer
(Boğaziçi Üniversitesi İktisadi ve İdari Bilimler Fakültesi, 2016) Özener, Başak Altan; Sunay, Mehmet Oğuz; Economics; Computer Science; ÖZENER, Başak Altan; SUNAY, Mehmet Oğuz
This study identifies optimal transmission mechanisms for a video streaming service in a peer-to-peer network structure under different payment mechanisms: pay as you watch and pay upfront. We calculate a uniform, feasible service price using the utilities of the users and associated server profits for every possible peer-to-peer distribution tree. We prove that when the server has linear or concave costs, the client-server structure is more profitable than any peer-to-peer structure. This statement holds even when the users have maximal tolerance to indefinitely long pre-roll delays. When the server however, has convex costs, we show that the optimal network structure depends on the system parameters and there is no single distribution mechanism that provides the optimal server profit for every operating point of the network.
Open Access
Çocuğa yapılan zaman yatırımlarının i̇ş gücü pi̇yasasindaki̇ kadın-erkek ücret farklılığına etki̇leri̇
(Hacettepe Üniversitesi, 2017-01-23) Soytaş, Mehmet Ali; Economics; SOYTAŞ, Mehmet Ali
Öz kadarını kullandıklarının ve bunun demografik özelliklerle nasıl değiştiğinin anlaşılması için, kadın ve çocuklarının oluşturduğu bir veri seti kullanarak model tahmini yapmaktır. Nesiller arası yapı, çocukların yetişkin çıktılarını toplulaştırmak için doğal bir yol sağlar çünkü bu çıktılar modelde gelecek jenerasyondaki çocukların değer fonksiyonu ile ölçülür. Bu ölçüt, çocuklara yapılan yatırımların beklenen getirisi için iyi bir temsil sağlar. Kadının değer fonksiyonu, hem kendi çalışmadığı durumdaki gelir kaybını, hem de yatırım yaptığı durumda çocuklarına dair beklentileri içerir. Bu iki faktörden ikincisinin, ilkinden kaynaklanan kaybı telafi ettiği ölçüde, kadınlar iş gücü piyasasında çalışmaya harcadıkları ödünleşme aynı zamanda eğitime de dayalıdır, dolayısıyla her ikisinde de iyi olabilecek eğitimli kadınlar için durumu daha da marjinal hale getirmektedir. Tahmin edilen model ve politika simülasyonları, zaman yatırımının kadınların iş gücü tercihini etkileyen önemli bir kanal olduğunu ve zaman yatırımının çocukların gelecekteki çıktılarını etkilemede önemli bir rol oynadığını bulunmuştur.
Open Access
Company innovation system: a conceptualization
(Operations and Information Management Group, Aston Business School, Aston University, 2018-04-25) den Hartigh, Erik; Entrepreneurship; Nunes, B.; Emrouznejad, A.; Bennett, D.; Pretorius, L.; HARTIGH, Erık Den
We conceptualize the company as an innovation system that consists of components, relationships and attributes, with the purpose to produce innovation. The systems approach to innovation has received limited attention at the company level. While it is widely accepted for nations, sectors, regions and technologies, and while some company-level foundations and building blocks have been proposed, the dominant approach at company level is to regard innovation as a process. Components of a company innovation system are actors or resources. Relationships refer to the configuration of these components: an innovation process now becomes one of the possible configurations of components in a system. Attributes of a company innovation system are capabilities and other system properties, such as innovative culture or infrastructure. We explore the concept of company innovation system by analyzing and comparing case examples of ABB Group, Adobe Systems, Amazon.com, eBay, Hitachi, HTC, Lockheed Martin, Philips, Qualcomm, Salesforce.com and Southwest Airlines. We find that using the company innovation system approach, we can map innovation systems at the company level. We can identify the components, such as R&D departments, labs, venture organizations, teams, employees, C-level offices and facilitating tools. We can identify relationships such as single or multiple configurations, simple or complex configurations, technology-driven, market-driven or interactive configurations, and open or closed configurations. We can identify attributes such as creativity versus efficiency emphasis, systematic versus non-systematic approaches, adaptiveness of the system, and large project-focus versus experimentation focus. The findings indicate that companies design, configure and coordinate their innovation systems in different ways. Our current findings are tentative and preliminary and only provide descriptive insights of the case examples. A well-conceptualized and validated company innovation system approach may give managers relevant insights to address the problems of designing, configuring and coordinating their company innovation systems. Academically, the company innovation system approach provides complementary insights to the existing company-level innovation approaches.
Open Access
Computational comparison of five maximal covering models for locating ambulances
(Wiley, 2009-01) Erkut, Erhan; Ingolfsson, A.; Sim, T.; Erdoğan, Güneş; Business Administration; Industrial Engineering; ERKUT, Erhan; ERDOĞAN, Güneş
This article categorizes existing maximum coverage optimization models for locatingambulances based on whether the models incorporate uncertainty about (1) ambulanceavailability and (2) response times. Data from Edmonton, Alberta, Canada are used to test five different models, using the approximate hypercube model to compare solution quality between models. The basic maximum covering model, which ignores these two sources of uncertainty, generates solutions that perform far worse than those generated by more sophisticated models. For a specified number of ambulances, a model that incorporates both sources of uncertainty generates a configuration that covers up to 26% more of the demand than the configuration produced by the basic model.
Open Access
Consumer attitude metrics for guiding marketing mix decisions
(Informs, 2014-08) Hanssens, D. M.; Pauwels, Koen Hendrik; Srinivasan, S.; Vanhuele, M.; Yildirim, G.; Business Administration; PAUWELS, Koen Hendrik
Marketing managers often use consumer attitude metrics such as awareness, consideration, and preference as performance indicators because they represent their brand's health and are readily connected to marketing activity. However, this does not mean that financially focused executives know how such metrics translate into sales performance, which would allow them to make beneficial marketing mix decisions. We propose four criteria-potential, responsiveness, stickiness, and sales conversion-that determine the connection between marketing actions, attitudinal metrics, and sales outcomes. We test our approach with a rich data set of four-weekly marketing actions, attitude metrics, and sales for several consumer brands in four categories over a seven-year period. The results quantify how marketing actions affect sales performance through their differential impact on attitudinal metrics, as captured by our proposed criteria. We find that marketing-attitude and attitude-sales relationships are predominantly stable over time but differ substantially across brands and product categories. We also establish that combining marketing and attitudinal metrics criteria improves the prediction of brand sales performance, often substantially so. Based on these insights, we provide specific recommendations on improving the marketing mix for different brands, and we validate them in a holdout sample. For managers and researchers alike, our criteria offer a verifiable explanation for differences in marketing elasticities and an actionable connection between marketing and financial performance metrics.
Open Access
Consumers and brands across the globe: research synthesis and new directions
(American Marketing Association, 2018-03) Gürhan-Canli, Z.; Sarıal-Abi, G.; Şanlı, Ceren Hayran; Business Administration; ŞANLI, Ceren Hayran
Extensive research has investigated branding practices, processes, and consumers’ reactions to brands in a globalized world. In this review, the authors aim to organize and synthesize the growing literature on branding, culture, and globalization from a behavioral perspective by reviewing 129 articles published over 25 years. Specifically, they explicate two perspectives found in the literature: (1) global–local branding and (2) the influence of culture on consumer and brand interactions. The authors identify conceptual gaps in the literature and discuss how new realities in the macro environment (e.g., political issues, digital transformation, environmental concerns) may affect the interaction between culture, brands, and consumers in a globalized world. This review facilitates a more impactful future research agenda in both theory and practice at the interface of branding and globalization from the perspective of behavioral outcomes.
Open Access
Corporate sustainability interactions: A game theoretical approach to sustainability decisions
(Elsevier, 2019-12) Soytaş, Mehmet Ali; Uşar, Damla Durak; Denizel, M.; Soytaş, Mehmet Ali; Uşar, Damla Durak
Recent global developments lead companies to include into their strategic plans not only economic sustainability but environmental and social sustainability as well. Companies have been investing in environmental and social sustainability to meet stakeholder demand and/or regulatory demands. Considering this as a market mechanism, we view the sustainability actions of companies as interrelated strategic decisions and propose a Stackelberg game to model the effects of competition for sustainability and sustainability spillovers over the sustainability outcomes of companies. We provide equilibrium solutions for the one leader, two followers game over different intervals of competition levels and spillover rates. Using a numerical example, we observe how the sustainability investments and net benefits change as competition levels and spillover rates change and identify the competition-spillover regions, where each player invests the most and has the advantage in terms of benefit. We discuss implications for both the companies and the policy makers.
Open Access
Development and calibration of a currency trading strategy using global optimization
(Springer Science+Business Media, 2013-06) Çağlayan, Mustafa Onur; Pinter, Janos D.; Economics; Industrial Engineering; ÇAĞLAYAN, Mustafa Onur; PINTER, Janos
We have developed a new financial indicator—called the Interest Rate Differentials Adjusted for Volatility (IRDAV) measure—to assist investors in currency markets. On a monthly basis, we rank currency pairs according to this measure and then select a basket of pairs with the highest IRDAV values. Under positive market conditions, an IRDAV based investment strategy (buying a currency with high interest rate and simultaneously selling a currency with low interest rate, after adjusting for volatility of the currency pairs in question) can generate significant returns. However, when the markets turn for the worse and crisis situations evolve, investors exit such money-making strategies suddenly, and—as a result—significant losses can occur. In an effort to minimize these potential losses, we also propose an aggregated Risk Metric that estimates the total risk by looking at various financial indicators across different markets. These risk indicators are used to get timely signals of evolving crises and to flip the strategy from long to short in a timely fashion, to prevent losses and make further gains even during crisis periods. Since our proprietary model is implemented in Excel as a highly nonlinear “black box” computational procedure, we use suitable global optimization methodology and software—the Lipschitz Global Optimizer solver suite linked to Excel—to maximize the performance of the currency basket, based on our selection of key decision variables. After the introduction of the new currency trading model and its implementation, we present numerical results based on actual market data. Our results clearly show the advantages of using global optimization based parameter settings, compared to the typically used “expert estimates” of the key model parameters.

Browse

Browsing by Rights "info:eu-repo/semantics/openAccess"