Publications with Fulltext
Permanent URI for this collectionhttps://hdl.handle.net/20.500.14288/6
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Publication Open Access Base-rate information in consumer attributions of product-harm crises(American Marketing Association (AMA), 2012) Lei, Jing; Dawar, Niraj; Department of Business Administration; Department of Business Administration; Canlı, Zeynep Gürhan; Researcher; Department of Business Administration; College of Administrative Sciences and Economics; 16135Consumers spontaneously construct attributions for negative events such as product-harm crises. Base-rate information influences these attributions. The research findings suggest that for brands with positive prior beliefs, a high (vs. low) base rate of product-harm crises leads to less blame if the crisis is said to be similar to others in the industry (referred to as the "discounting effect"). However, in the absence of similarity information, a low (vs. high) base rate of crises leads to less blame toward the brand (referred to as the "subtyping effect"). For brands with negative prior beliefs, the extent of blame attributed to the brand is unaffected by the base-rate and similarity information. Importantly, the same base-rate information may have a different effect on the attribution of a subsequent crisis depending on whether discounting or subtyping occurred in the attribution of the first crisis. Consumers who discount a first crisis also tend to discount a second crisis for the same brand, whereas consumers who subtype a first crisis are unlikely to subtype again.Publication Open Access Positioning multicountry brands: the impact of variation in cultural values and competitive set(American Marketing Association (AMA), 2017) Batra, Rajeev; Zhang, Y. Charles; Feinberg, Fred M.; Department of Business Administration; Aydınoğlu, Nilüfer Zümrüt; Faculty Member; Department of Business Administration; College of Administrative Sciences and Economics; 114037Building on cultural values research, the authors identify specific image attributes on which multicountry brands should position themselves consistently across markets. Leveraging prior research, they identify three life values that are most equal (benevolence, universalism, and self-direction) and two that are least equal (power and hedonism) in cross-national importance. The authors link specific brand image attributes (e.g., friendly, social, elite style, arrogant) to these life values through empirical data and semantic analysis. Using an extensive field data set on consumer perceptions and preferences from 22 countries regarding more than 1,700 brands, the authors then show that greater global consistency of a brand's image decreases overall brand attitudes if the specific image attribute is one that is not equally desired worldwide. They also find that the attitudinal impact of a multicountry brand's positioning consistency on commonly valued image attributes is greater when the set of competitors the brand faces across its markets is more homogeneous. The authors discuss implications for global brand management theory and practice.Publication Open Access Looming losses in future time perception(American Marketing Association (AMA), 2010) LeBoeuf, Robyn A.; Department of Business Administration; Department of Business Administration; Bilgin, Baler; Faculty Member; Department of Business Administration; College of Administrative Sciences and Economics; 108641It is proposed that a future time interval's perceived length will be affected by whether the interval ends with a gain or loss. Confirming this, several experiments indicate that consumers perceive intervals ending with losses as shorter than equivalent intervals ending with gains. The authors explore the mechanisms underlying these effects, and they identify several parallels between the current effects and loss aversion. The authors further show that these changes in time perception influence consumption decisions, and they consider the implications of the findings for theories of time perception and intertemporal choice.Publication Open Access Estimating the potential impact of behavioral public health interventions nationally while maintaining agreement with global patterns on relative risks(Public Library of Science, 2020) Department of Business Administration; N/A; Ali, Özden Gür; Ghanem, Angi Nazih; Üstün, Tevfik Bedirhan; Faculty Member; Faculty Member; Department of Business Administration; College of Administrative Sciences and Economics; Graduate School of Sciences and Engineering; School of Medicine; 57780; N/A; 261811Objective: this paper introduces a novel method to evaluate the local impact of behavioral scenarios on disease prevalence and burden with representative individual level data while ensuring that the model is in agreement with the qualitative patterns of global relative risk (RR) estimates. The method is used to estimate the impact of behavioral scenarios on the burden of disease due to ischemic heart disease (IHD) and diabetes in the Turkish adult population. Methods: disease specific Hierarchical Bayes (HB) models estimate the individual disease probability as a function of behaviors, demographics, socio-economics and other controls, where constraints are specified based on the global RR estimates. The simulator combines the counterfactual disease probability estimates with disability adjusted life year (DALY)-per-prevalent-case estimates and rolls up to the targeted population level, thus reflecting the local joint distribution of exposures. The Global Burden of Disease (GBD) 2016 study meta-analysis results guide the analysis of the Turkish National Health Surveys (2008 to 2016) that contain more than 90 thousand observations. Findings: the proposed Qualitative Informative HB models do not sacrifice predictive accuracy versus benchmarks (logistic regression and HB models with non-informative and numerical informative priors) while agreeing with the global patterns. In the Turkish adult population, Increasing Physical Activity reduces the DALYs substantially for both IHD by 8.6% (6.4% 11.2%), and Diabetes by 8.1% (5.8% 10.6%), (90% uncertainty intervals). Eliminating Smoking and Second-hand Smoke predominantly decreases the IHD burden 13.1% (10.4% 15.8%) versus Diabetes 2.8% (1.1% 4.6%). Increasing Fruit and Vegetable Consumption, on the other hand, reduces IHD DALYs by 4.1% (2.8% 5.4%) while not improving the Diabetes burden 0.1% (0% 0.1%). Conclusion: while the national RR estimates are in qualitative agreement with the global patterns, the scenario impact estimates are markedly different than the attributable risk estimates from the GBD analysis and allow evaluation of practical scenarios with multiple behaviors.Publication Open Access Heterogeneous price effects of consolidation:evidence from the car rental industry(The Institute for Operations Research and the Management Sciences (INFORMS), 2020) Misra, Kanishka; Singh, Vishal; Department of Business Administration; Güler, Ali Umut; Faculty Member; Department of Business Administration; College of Administrative Sciences and Economics; 143349We study the price effects of consolidation in the car rental industry using three cross-sections of price data from U.S. airport markets spanning the years 2005 to 2016. The auto rental industry went through a series of mergers during this period, leading to a significant increase in market concentration. We find that the concentration of ownership affects the business (weekday) and leisure (weekend) segments differently. Average weekday prices rose by 2.1% and weekend prices fell by 3.3% with the increase in market concentration. Given the periodic differences in demand from business and leisure travelers, we explain this finding with a model of horizontal product differentiation that allows for heterogeneity in customer types and firms’ marginal costs. Consolidation leads to marginal cost savings, but the extent to which these savings are passed onto different customer types depends on the magnitude of switching costs. In particular, weekday customers with high switching costs are charged higher prices because of suppliers’ augmented market power whereas the more price-sensitive weekend segment enjoys the lower prices facilitated by efficiency gains. Our findings highlight that consolidation can have differential welfare effects on different customer groups and merger analyses should account for the heterogeneous impact based on firms’ price discrimination practices rather than just considering average effects.Publication Open Access Impact of delay announcements in call centers: an empirical approach(Informs, 2017) Ata, B.; Emadi, Sm.; Su, Cl.; Department of Business Administration; Karaesmen, Zeynep Akşin; Faculty Member; Department of Business Administration; College of Administrative Sciences and Economics; 4534We undertake an empirical study of the impact of delay announcements on callers' abandonment behavior and the performance of a call center with two priority classes. A Cox regression analysis reveals that in this call center, callers' abandonment behavior is affected by the announcement messages heard. To account for this, we formulate a structural estimation model of callers' (endogenous) abandonment decisions. In this model, callers are forward-looking utility maximizers and make their abandonment decisions by solving an optimal stopping problem. Each caller receives a reward from service and incurs a linear cost of waiting. The reward and per-period waiting cost constitute the structural parameters that we estimate from the data of callers' abandonment decisions as well as the announcement messages heard. The call center performance is modeled by a Markovian approximation. The main methodological contribution is the definition of an equilibrium in steady state as one where callers' expectation of their waiting time, which affects their (rational) abandonment behavior, matches their actual waiting time in the call center, as well as the characterization of such an equilibrium as the solution of a set of nonlinear equations. A counterfactual analysis shows that callers react to longer delay announcements by abandoning earlier, that less patient callers as characterized by their reward and cost parameters react more to delay announcements, and that congestion in the call center at the time of the call affects caller reactions to delay announcements.Publication Open Access Managing manufacturing risks by using capacity options(Springer, 2002) Department of Business Administration; Tan, Barış; Faculty Member; Department of Business Administration; College of Administrative Sciences and Economics; 28600In this study, we investigate the strategy of increasing production capacity temporarily through contingent contractual agreements with short-cycle manufacturers to manage the risks associated with demand volatility. We view all these agreements as capacity options. More specifically, we consider a manufacturing company that produces a replenishment product that is sold at a retailer. The demand for the product switches randomly between a high level and a low level. The production system has enough capacity to meet the demand in the long run. However, when the demand is high, it does not have enough capacity to meet the instantaneous demand and thus has to produce to stock in advance. Alternatively, a contractual agreement with a short-cycle manufacturer can be made. This option gives the right to receive additional production capacity when needed. There is a fixed cost to purchase this option for a period of time and, if the option is exercised, there is an additional per unit exercise price which corresponds to the cost of the goods produced at the short-cycle manufacturer. We formulate the problem as a stochastic optimal control problem and analyse it analytically. By comparing the costs between two cases where the contract with the short-cycle manufacturer is used or not, the value of this option is evaluated. Furthermore, the effect of demand variability on this contract is investigated.Publication Open Access Stochastic cyclic scheduling problem in synchronous assembly and production lines(Taylor _ Francis, 1998) Department of Business Administration; Tan, Barış; Karabatı, Selçuk; Faculty Member; Faculty Member; Department of Business Administration; College of Administrative Sciences and Economics; 28600; 38819In this paper we address the stochastic cyclic scheduling problem in synchronous assembly and production lines. Synchronous lines are widely used in the production and assembly of various goods such as automobiles or household appliances. We consider cycle time minimisation (or throughput rate maximisation) as the objective of the scheduling problem with the assumption that the processing times are independent random variables. We first discuss the two-station case and present a lower bounding scheme and an approximate solution procedure for the scheduling problem. For the general case of the problem, two heuristic solution procedures are presented. An extension of the two-station lower bound to the general case of the problem is also discussed. The performance of the proposed heuristics on randomly generated problems is documented, and the impact of scheduling decisions on problems with different levels of variability in processing times are analysed. We also analyse the problem of sequence determination when the available information is limited to the expected values of individual processing times.Publication Open Access A trilevel r-interdiction selective multi-depot vehicle routing problem with depot protection(Elsevier, 2020) Hesam Sadati, Mir Ehsan; Aras, Necati; Department of Business Administration; Aksen, Deniz; Faculty Member; Department of Business Administration; College of Administrative Sciences and Economics; 40308The determination of critical facilities in supply chain networks has been attracting the interest of the Operations Research community. Critical facilities refer to structures including bridges, railways, train/metro stations, medical facilities, roads, warehouses, and power stations among others, which are vital to the functioning of the network. In this study we address a trilevel optimization problem for the protection of depots of utmost importance in a routing network against an intelligent adversary. We formulate the problem as a defender-attacker-defender game and refer to it as the trilevel r-interdiction selective multi-depot vehicle routing problem (3LRI-SMDVRP). The defender is the decision maker in the upper level problem (ULP) who picks u depots to protect among m existing ones. In the middle level problem (MLP), the attacker destroys r depots among the (m–u) unprotected ones to bring about the biggest disruption. Finally, in the lower level problem (LLP), the decision maker is again the defender who optimizes the vehicle routes and thereby selects which customers to visit and serve in the wake of the attack. All three levels have an identical objective function which is comprised of three components. (i) Operating or acquisition cost of the vehicles. (ii) Traveling cost incurred by the vehicles. (iii) Outsourcing cost due to unvisited customers. The defender aspires to minimize this objective function while the attacker tries to maximize it. As a solution approach to this trilevel discrete optimization problem, we resort to a smart exhaustive enumeration in the ULP and MLP. For the LLP we design a metaheuristic algorithm that hybridizes Variable Neighborhood Descent and Tabu Search techniques adapted to the Selective MDVRP (SMDVRP). The performance of this algorithm is demonstrated on 33 MDVRP benchmark instances existing in the literature and 41 SMDVRP instances generated from them. Numerical experiments on a large number of 3LRI-SMDVRP instances attest that our comprehensive method is effective in dealing with the defender-attacker-defender game on multi-depot routing networks.Publication Open Access A multiperiod stochastic production planning and sourcing problem with service level constraints(Springer, 2005) Yıldırım, Işıl; Department of Business Administration; Department of Industrial Engineering; Tan, Barış; Karaesmen, Fikri; Faculty Member; Faculty Member; Department of Business Administration; Department of Industrial Engineering; College of Administrative Sciences and Economics; College of Engineering; 28600; 3579We study a stochastic multiperiod production planning and sourcing problem of a manufacturer with a number of plants and/or subcontractors. Each source, i.e. each plant and subcontractor, has a different production cost, capacity, and lead time. The manufacturer has to meet the demand for different products according to the service level requirements set by its customers. The demand for each product in each period is random. We present a methodology that a manufacturer can utilize to make its production and sourcing decisions, i.e., to decide how much to produce, when to produce, where to produce, how much inventory to carry, etc. This methodology is based on a mathematical programming approach. The randomness in demand and related probabilistic service level constraints are integrated in a deterministic mathematical program by adding a number of additional linear constraints. Using a rolling horizon approach that solves the deterministic equivalent problem based on the available data at each time period yields an approximate solution to the original dynamic problem. We show that this approach yields the same result as the base stock policy for a single plant with stationary demand. For a system with dual sources, we show that the results obtained from solving the deterministic equivalent model on a rolling horizon gives similar results to a threshold subcontracting policy.
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