Researcher:
Karaesmen, Zeynep Akşin

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Zeynep Akşin

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Karaesmen

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Researcher Of Publications: search.filters.isAuthorOfPublication.b70acda0-c9ab-4386-965b-13bccfd00248

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Now showing 1 - 10 of 21
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    Value creation in service delivery: relating market segmentation, incentives, and operational performance
    (Institute for Operations Research and the Management Sciences, 2004) Güneş, Evrim D.; Department of Business Administration; Karaesmen, Zeynep Akşin; Faculty Member; Department of Business Administration; College of Administrative Sciences and Economics; 4534
    This paper studies service-delivery design in settings where firms engage in value-creation activities that have the objective of generating additional revenue from customer interactions. The paper provides a general modelling framework to analyze the ties between market segmentation decisions, incentives, and process performance in such service-delivery systems. The firm is modelled as a single-server queue, in a principal-agent framework. Customers have different value-generation potentials whose realizations are observed by the server but not by the manager of the firm. The manager determines a market segmentation scheme given an overall customer value-generation profile, which divides customers into two groups (high and low), and also determines a service level for each segment. The server decides which of the two available service levels (high and low) to provide for each customer, given a compensation scheme offered by the manager. The optimal market segmentation decision, optimal service-level choice, and a set of optimal linear incentive contracts that enable their implementation are characterized. The robustness of these strategies is explored with respect to model parameters and assumptions. It is shown that a market segmentation scheme that combines revenue generation concerns with their process implications is essential for success. Characteristics of appropriate incentive schemes are identified.
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    Call centers with delay information: models and insights
    (Informs, 2011) Jouini, Oualid; Dallery, Yves; Department of Business Administration; Karaesmen, Zeynep Akşin; Faculty Member; Department of Business Administration; College of Administrative Sciences and Economics; 4534
    In this paper, we analyze a call center with impatient customers. We study how informing customers about their anticipated delays affects performance. Customers react by balking upon hearing the delay announcement and may subsequently renege, particularly if the realized waiting time exceeds the delay that has originally been announced to them. The balking and reneging from such a system are a function of the delay announcement. Modeling the call center as an M/M/s+M queue with endogenized customer reactions to announcements, we analytically characterize performance measures for this model. The analysis allows us to explore the role announcing different percentiles of the waiting time distribution, i.e., announcement coverage, plays on subsequent performance in terms of balking and reneging. Through a numerical study, we explore when informing customers about delays is beneficial and what the optimal coverage should be in these announcements. We show how managers of a call center with delay announcements can control the trade-off between balking and reneging through their choice of announcements to be made.
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    Effective strategies for internal outsourcing and offshoring of business services: an empirical investigation
    (Wiley, 2008) Masini, Andrea; Department of Business Administration; Karaesmen, Zeynep Akşin; Faculty Member; Department of Business Administration; College of Administrative Sciences and Economics; 4534
    The growing pressure to reduce costs and improve efficiency induces many organizations to undertake shared services initiatives. This consolidation and streamlining of common business functions is also known as insourcing, in-house services, business services, or staff services. While adoption of a shared service structure is viewed by many as an appropriate strategy to pursue, most companies still struggle to devise optimal strategies and to generate adequate returns on investments for their projects, because none of the approaches that are commonly adopted is recognized as universally effective. This paper builds upon the "structure-environment" perspective to uncover configurations of shared services organizations and to explain why and under what circumstances some of these configurations exhibit superior results. The conceptual model proposed challenges the notion of "best practice" and suggests that the effectiveness of a shared services project depends on the degree of complementarity between the "needs" arising from the environment in which a company operates and the specific capabilities developed to address these needs. The theoretical findings are validated empirically through the analysis of a large sample of European firms that recently undertook initiatives in this domain. Four dominant configurations of shared service organizations are uncovered, and their relationship to performance is explored.
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    The impact of retrials on call center performance
    (Springer, 2004) Aguir, Salah; Chauvet, Fabrice; Department of Industrial Engineering; Department of Business Administration; Karaesmen, Fikri; Karaesmen, Zeynep Akşin; Faculty Member; Faculty Member; Department of Industrial Engineering; Department of Business Administration; College of Engineering; College of Administrative Sciences and Economics; 3579; 4534
    This paper models a call center as a Markovian queue with multiple servers, where customer balking, impatience, and retrials are modeled explicitly. The resulting queue is analyzed both in a stationary and non-stationary setting. For the stationary setting a fluid approximation is proposed, which overcomes the computational burden of the continuous time markov chain analysis, and which is shown to provide an accurate representation of the system for large call centers with high system load. An insensitivity property of the retrial rate to key system parameters is established. The fluid approximation is shown to work equally well for the non-stationary setting with time varying arrival rates. Using the fluid approximation, the paper explores the retrial phenomenon for a real call center. The model is used to estimate the real arrival rates based on demand data where retrials cannot be distinguished from first time calls. This is a common problem encountered in call centers. Through numerical examples, it is shown that disregarding the retrial phenomenon in call centers can lead to huge distortions in subsequent forecasting and staffing analysis.
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    Call center outsourcing contract analysis and choice
    (Informs, 2008) de Vericourt, Francis; Department of Business Administration; Department of Industrial Engineering; Karaesmen, Zeynep Akşin; Karaesmen, Fikri; Faculty Member; Faculty Member; Department of Business Administration; Department of Industrial Engineering; College of Administrative Sciences and Economics; College of Engineering; 4534; 3579
    This paper considers a call center outsourcing contract analysis and choice problem faced by a contractor and a service provider. The service provider receives an uncertain call volume over multiple periods and is considering outsourcing all or part of these calls to a contractor. Each call brings in a fixed revenue to the service provider. Answering calls requires having service capacity; thus implicit in the outsourcing decision is a capacity decision. Insufficient capacity implies that calls cannot be answered, which in turn means there will be a revenue loss. Faced, with a choice between a volume-based and a capacity-based contract offered by a contractor that has pricing power, the service provider determines optimal capacity levels. The optimal price and capacity of the contractor together with the optimal capacity of the service provider determine optimal profits of each party under the two contracts being considered. This paper characterizes optimal capacity levels and partially characterizes optimal pricing decisions under each contract. The impact of demand variability and the economic parameters on contract choice are explored through numerical examples. It is shown that no contract type is universally preferred and that operating environments as well as cost-revenue structures have an important effect.
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    Structural estimation of callers' delay sensitivity in call centers
    (Informs, 2013) Emadi, Seyed Morteza; Su, Che-Lin; Department of Business Administration; N/A; Karaesmen, Zeynep Akşin; Ata, Mustafa Barış; Faculty Member; Doctor; Department of Business Administration; College of Administrative Sciences and Economics; Koç University Hospital; 4534; 182910
    We model the decision-making process of callers in call centers as an optimal stopping problem. After each waiting period, a caller decides whether to abandon a call or continue to wait. The utility of a caller is modeled as a function of her waiting cost and reward for service. We use a random-coefficients model to capture the heterogeneity of the callers and estimate the cost and reward parameters of the callers using the data from individual calls made to an Israeli call center. We also conduct a series of counterfactual analyses that explore the effects of changes in service discipline on resulting waiting times and abandonment rates. Our analysis reveals that modeling endogenous caller behavior can be important. when major changes (such as a change in service discipline) are implemented and that using a model with an exogenously specified abandonment distribution may be misleading.
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    On the interaction between retrials and sizing of call centers
    (Elsevier, 2008) Aguir, M. Salah; Dallery, Yves; Department of Business Administration; Department of Industrial Engineering; Karaesmen, Zeynep Akşin; Karaesmen, Fikri; Faculty Member; Faculty Member; Department of Business Administration; Department of Industrial Engineering; College of Administrative Sciences and Economics; College of Engineering; 4534; 3579
    This paper models a call center as a Markovian queue with multiple servers, where customer impatience, and retrials are modeled explicitly. The model is analyzed as a continuous time Markov chain. The retrial phenomenon is explored numerically using a real example, to demonstrate the magnitude it can take and to understand its sensitivity to various system parameters. The model is then used to assess the impact of disregarding existing retrials in the staffing of a call center. It is shown that ignoring retrials can lead to under-staffing or over-staffing with respect to the optimal, depending on the forecasting assumptions being made.
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    Call center delay announcement using a newsvendor-like performance criterion
    (Wiley, 2015) Jouini, Oualid; Aguir, M. Salah; Dallery, Yves; Department of Business Administration; Department of Industrial Engineering; Karaesmen, Zeynep Akşin; Karaesmen, Fikri; Faculty Member; Faculty Member; Department of Business Administration; Department of Industrial Engineering; College of Administrative Sciences and Economics; College of Engineering; 4534; 3579
    The problem of estimating delays experienced by customers with different priorities, and the determination of the appropriate delay announcement to these customers, in a multi-class call center with time varying parameters, abandonments, and retrials is considered. The system is approximately modeled as an M(t)/M/s(t) queue with priorities, thus ignoring some of the real features like abandonments and retrials. Two delay estimators are proposed and tested in a series of simulation experiments. Making use of actual state-dependent waiting time data from this call center, the delay announcements from the estimated delay distributions that minimize a newsvendor-like cost function are considered. The performance of these announcements is also compared to announcing the mean delay. We find that an Erlang distribution-based estimator performs well for a range of different under-announcement penalty to over-announcement penalty ratios.
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    Breast cancer screening services: trade-offs in quality, capacity, outreach, and centralization
    (Springer Nature, 2004) Chick, Stephen E.; Güneş, Evrim D.; Department of Business Administration; Karaesmen, Zeynep Akşin; Faculty Member; Department of Business Administration; College of Administrative Sciences and Economics; 4534
    This work combines and extends previous work on breast cancer screening models by explicitly incorporating, for the first time, aspects of the dynamics of health care states, program outreach, and the screening volume-quality relationship in a service system model to examine the effect of public health policy and service capacity decisions on public health outcomes. We consider the impact of increasing standards for minimum reading volume to improve quality, expanding outreach with or without decentralization of service facilities, and the potential of queueing due to stochastic effects and limited capacity. The results indicate a strong relation between screening quality and the cost of screening and treatment, and emphasize the importance of accounting for service dynamics when assessing the performance of health care interventions. For breast cancer screening, increasing outreach without improving quality and maintaining capacity results in less benefit than predicted by standard models.
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    Peakedness-based staffing for call center outsourcing
    (Wiley, 2014) Van den Schrieck, Jean-Christophe; Chevalier, Philippe; Department of Business Administration; Karaesmen, Zeynep Akşin; Faculty Member; Department of Business Administration; College of Administrative Sciences and Economics; 4534
    This study considers the staffing problem of a vendor call center in a co-sourcing setting. The aim is to take short-term variability and correlations in time for call arrivals at such a vendor call center into account. To do so, peakedness is proposed as a useful measure of the burstiness in the arrival stream. The study empirically demonstrates the presence of bursty arrivals at a call center and proposes an approach to the measurement of the peakedness of the arrival stream making use of standard call center data. The problematic nature of bursty arrivals in the context of call center co-sourcing is demonstrated along with an asymptotic result establishing that the problem persists in large call centers. The study then analyzes two peakedness-based staffing methods: one which is a well known extension of the square root staffing rule and another which makes use of the Hayward approximation principles. Both approaches are simple and enable the vendor to improve its staffing procedure with good accuracy.