http://repub.eur.nl/res/concept/jel-L23/ Recent publications classified by JEL Code L23 en http://repub.eur.nl/static-eur/img/logo.png http://repub.eur.nl http://repub.eur.nl/res/pub/37297/ 2012-05-01T00:00:00Z We model entrepreneurship and the emergence of firms as an outcome of simultaneous bidding for labor services among heterogeneous agents. What distinguishes our approach from prior work is that occupational choice and job matching are determined simultaneously, so that the opportunity costs of entrepreneurs are accounted for. Those who are relatively unmanageable, while possibly excellent managers themselves, become entrepreneurs. Entrepreneurs compete and create value by building efficient organizations and offering potentially well-paid jobs to others. While the entry of an additional entrepreneur typically reduces some individual wages, we show that it always raises the average wage and depresses the average income of incumbent entrepreneurs. This result may help explain the empirically low returns to entrepreneurship. Roessler, C. Koellinger, Ph.D. http://repub.eur.nl/res/pub/37798/ 2012-04-01T00:00:00Z We determine the circumstances when the absence of public listing, often believed to be a disadvantage, makes a cooperative the unique efficient governance structure. This is established in a multi-task principal-agent model, capturing that cooperatives are not publicly listed and their CEOs have to bring the downstream enterprise to value as well as to serve upstream member interests. Not having a public listing prevents the CEO from choosing the level of the downstream activities too high. Cooperatives are uniquely efficient when the upstream marginal product multiplied with a function increasing in the strength of the chain complementarities is higher than the downstream marginal product. Feng, L. Hendrikse, G.W.J. http://repub.eur.nl/res/pub/37296/ 2012-02-23T00:00:00Z We model entrepreneurship and the emergence of …rms as an out- come of simultaneous bidding for labor services among heterogeneous agents. What distinguishes our approach from prior work is that oc- cupational choice and job matching are determined simultaneously, so that the opportunity costs of entrepreneurs are accounted for. Those who are relatively unmanageable, while possibly excellent managers themselves, become entrepreneurs. Entrepreneurs compete and create value by building e¢ cient organizations and o¤ering potentially well- paid jobs to others. While the entry of an additional entrepreneur typically reduces some individual wages, we show that it always raises the average wage and depresses the average income of incumbent en- trepreneurs. This result may help explain the empirically low returns to entrepreneurship. Roessler, C. Koellinger, Ph.D. http://repub.eur.nl/res/pub/19867/ 2010-06-24T00:00:00Z In this study, we develop and analyze models incorporating some of the dynamic aspects of inventory systems. In particular, we focus on two major themes to be analyzed separately: nonstationarity in demand rate and unfixed purchasing prices. In the first part of the study, we consider an inventory system with a nonstationary demand rate. In particular, we consider critical service parts subject to obsolescence. Inventory management of such items is notoriously difficult due to their slow moving character and the high risks involved when they are not available or no more needed. In practice, there is a need for policies tailored for service parts taking these aspects into account and easy to implement. We propose an obsolescence based control policy and investigate its performance and impact on costs. We find that ignoring obsolescence in the control policy increases costs significantly and early adaptation of base stock levels can lead to important savings. In the second part of the study, we consider an inventory system where the supplier offers price discounts at random points in time. We extend the literature by assuming a more general backordering structure. That is, when the system is out of stock, an arriving customer either decides to be backlogged with a certain probability or leaves the system and becomes a lost sale. We derive equations to calculate optimal policy parameters and demonstrate that allowing backorders in face of random deal offerings can result in considerable savings. Pinçe, C. http://repub.eur.nl/res/pub/19742/ 2010-06-10T00:00:00Z The development of logistics has offered a wide range of new business opportunities for transport operators. Shipping lines have been taking advantage of these opportunities and have expanded their business scope beyond the movement of cargo, to include, for example, coordination among transport modes, route rationalisation and even value added logistics services. Carriers offer today transportation as part of integrated global supply chain solutions in an attempt to provide a better service to their customers as well as improve their bottom lines. This appears to be a winning strategy since an increasing number of industry players are investing in logistics operations and infrastructure. The offering of products and services jointly as a package or bundle is a common marketing strategy in a variety of industries and also appears to be a successful strategy for enhancing shipping lines’ competitiveness and profitability. Only limited research is available though to better understand under what conditions such bundled sales are possible; what attitude shippers show towards this industry trend; how bundling strategies could be developed optimally; and how they could be priced. This thesis is a contribution to research in this area and provides an analysis of the viability and the benefits of bundling strategies in the container industry, and specifically with reference to the joint provision of ocean transportation and other logistics services. Acciaro, M. http://repub.eur.nl/res/pub/19678/ 2010-06-01T00:00:00Z The area under Receiver Operating Characteristic (ROC) curve, also known as the AUC-index, is commonly used for ranking the performance of data mining models. The AUC has many merits, such as objectivity and ease of interpretation. However, since it is class indifferent, its usefulness while dealing with highly skewed data sets is questionable, to say the least. In this paper, we propose a simple alternative scalar measure to the AUCindex, the Area Under an Kappa curve (AUK). The proposed AUK-index compensates for the above basic flaw of the AUC by being sensitive to the class distribution. Therefore it is particularly suitable for measuring classifiers’ performance on skewed data sets. After introducing the AUK we explore its mathematical relationship with the AUC and show that there is a nonlinear relation between them. Kaymak, U. Ben-David, A. Potharst, R. http://repub.eur.nl/res/pub/19668/ 2010-05-28T00:00:00Z Purpose: This paper examines the claim that the application of human factors (HF) knowledge can improve both human well-being and operations system performance. Methodology: A systematic review was conducted using a general and two specialist databases to identify empirical studies addressing both human effects and operations system effects in examining manufacturing operations system design aspects. Findings: We found 45 empirical studies addressing both the human effects and system effects of operations system (re)design. Of those studies providing clear directional effects, 95% showed a convergence between human effects and system effects (+,+ or -,-), 5% showed a divergence of human and system effects (+,- or -,+). System effects included quality, productivity, implementation performance of new technologies, and also more ‘intangible’ effects in terms of improved communication and co-operation. Human effects included employee health, attitudes, physical workload, and ‘quality of working life’. Research limitations/implications: Future research should attend to both human and system outcomes in trying to determine optimal configurations for operations systems as this appears to be a complex relationship with potential long-term impact on operational performance. Practical implications: The application of HF in operations system design can support improvement in both employee well-being and system performance in a number of manufacturing domains. Originality/value: This paper outlines and documents a research and practice gap between the fields of HF and OM research that has not been previously discussed in the management literature. This gap may be inhibiting the design of operations systems with superior long term performance. Neumann, W.P. Dul, J. http://repub.eur.nl/res/pub/19594/ 2010-05-21T00:00:00Z Collaboration between firms in order to coordinate supply chain operations can lead to both strategic and operational benefits. Many advanced forms of collaboration arrangements between firms exist with the aim to coordinate supply chain decisions and to reap these benefits. This dissertation contributes to the understanding of the conditions that are necessary for collaboration in such arrangements and the benefits that can be realized of such collaboration arrangements. This dissertation focuses on the vendor-buyer dyad in the supply chain. We identify and categorize collaboration arrangements that exist in practice, based on a review of the literature and combine this with formal analytical models in the literature. An important factor in the benefits of collaboration is the benefit of reduced costs of transport, by realization of economies of scale in the context of capacity-constrained trucks. As a contribution to the understanding of the dependence of transport costs on the volume transported, we demonstrate how transport tariffs for orders of less-than-a-truckload in size on a single link can be deduced from a basic model. The success of a collaboration arrangement depends on agreement about the distribution of decision authority and collaboration-benefits. We study a collaboration arrangement in which the vendor takes responsibility for managing the buyer's inventory and makes it economically attractive to the buyer by offering a financial incentive, dependent on the maximum level the buyer permits to be stocked. This dissertation demonstrates that this incentive alignment leads to considerable cost savings and near-optimal supply chain decisions. Verheijen, H.J.J. http://repub.eur.nl/res/pub/19197/ 2010-03-23T00:00:00Z This article uses correspondence analysis to visualize risk profiles and their changes over the time period 1977 to 2008. It is based on a unique dataset which combines incident data and ship particular data. The risk profiles can help stakeholders better understand the relationship of ship particulars, casualty types, incident locations, loss of life and pollution and link the results to developments of the legislative framework. The results demonstrate that the fleet improved their risk profiles over time reflecting legislative measures, port state control and vetting inspections. Older, general cargo ships flagged by black listed flags are most likely to be wrecked, stranded or grounded and remain risk prone towards flooding, foundering and capsizing. Some trading areas characterized by inter-regional trade operating outside the legislative framework remain risk prone. Most incidents do not involve loss of life or pollution. In terms of absolute figures, high risk prone areas for loss of life are the North and South China Sea, Japan and South Korea, the Mediterranean, Red and Black Sea and the Arabian Gulf. Casualty types which are more likely to lead to higher loss of life are flooding, foundering and capsizing on vessels which are flagged with black listed flags. For pollution, most oil pollution occurred in the area of the British Isles, the North Sea, the English Channel and the Bay of Biscay. High pollution quantities are more likely to be found due to collision and the vessel being wrecked, stranded and grounded than with other casualty types. Knapp, S. Velden, M. van de http://repub.eur.nl/res/pub/18041/ 2010-01-23T00:00:00Z A stochastic inventory routing problem (SIRP) is typically the combination of stochastic inventory control problems and NP-hard vehicle routing problems, for a depot to determine delivery volumes to its customers in each period, and vehicle routes to distribute the delivery volumes. This paper aims to solve a large scale multi-period SIRP with split delivery (SIRPSD) where a customer’s delivery in each period can be split and satisfied by multiple vehicles if necessary. The objective of the problem is to minimize the total inventory and transportation cost while some constraints are given to satisfy other criteria, such as the service level to limit the stockout probability at each customer and the service level to limit the overfilling probability of the warehouse of each customer. In order to tackle the SIRPSD with notorious computational complexity, we propose for it an approximate model, which significantly reduces the number of decision variables compared to its corresponding exact model. We develop a hybrid approach that combines the linearization of nonlinear constraints, the decomposition of the model into sub-models with Lagrangian relaxation, and a partial linearization approach for a sub model. A near optimal solution of the model can be found by the approach, and then be used to construct a near optimal solution of the SIRPSD. Numerical examples show that, for an instance of the problem with 200 customers and 5 periods that contains about 400 thousands decision variables where half of them are integer, our approach can obtain high quality near optimal solutions with a reasonable computational time on an ordinary PC. Yu, Y. Chu, C. Chen, H.X. Chu, F. http://repub.eur.nl/res/pub/17197/ 2009-11-02T00:00:00Z In this paper, we consider a continuous review inventory system of a slow moving item for which the demand rate drops to a lower level at a pre-determined time. Inventory system is controlled according to one-for-one replenishment policy with fixed lead time. Adaptation to the lower demand rate is achieved by changing the control policy in advance and letting the demand take away the excess stocks. We show that the timing of the control policy change primarily determines the tradeoff between backordering penalties and obsolescence costs. We propose an approximate solution for the optimal time to shift to the new control policy minimizing the expected total cost during the transient period. We find that the advance policy change results in significant cost savings and the approximation yields near optimal expected total costs. Pinçe, C. Dekker, R. http://repub.eur.nl/res/pub/16724/ 2009-09-03T00:00:00Z This thesis has studied stochastic models and analysis of warehouse operations. After an overview of stochastic research in warehouse operations, we explore the following topics. Firstly, we search optimal batch sizes in a parallel-aisle warehouse with online order arrivals. We employ a sample path optimization and perturbation analysis algorithm to search the optimal batch size for a warehousing service provider, and a central finite difference algorithm to search the optimal batch sizes from the perspectives of customers and total systems. Secondly, we research a polling-based dynamic order picking system for online retailers. We build models to describe and analyze such systems via stochastic polling theory, find closed-form expressions for the order line waiting times, and apply polling-based picking to online retailers. We then present closed-form analytic expressions for pick rates of order picking bucket brigades systems in different storage profiles, and show how to combine storage policies and bucket brigades protocols to improve order picking productivity. Finally, we propose a new warehouse design approach oriented to improving revenue management of public storage warehouses. Our experiments show a proper facility design can significantly improve the expected revenue of public storage warehouses. Gong, Y. http://repub.eur.nl/res/pub/17670/ 2009-08-28T00:00:00Z The three different areas and the examples have illustrated several catalytic functions of standards for innovation. First, the standardisation process reduces the time to market of inventions, research results and innovative technologies. Second, standards themselves promote the diffusion of innovative products, which is most important for the economic impact of innovation. A third more indirect, but important function of standards is that they level the playing field and therefore promote competition and consequently innovation. Fourth, compatibility standards are the basis for innovation in network industries e.g. for communication networks (e.g. GSM), which are increasingly penetrating our economies. In network industries, standards also facilitate the substitution of old technologies by new ones, e.g. by forward and backward compatibility, and also to allow the coexistence of old and new technologies. New platform standards are often the basis for innovation in downstream markets (e.g. GSM as platform for numerous mobile services), but also in upstream markets. Besides these network related functions, a generic characteristic of standards is that they reflect user needs and therefore promote the purchase, i.e. the diffusion, of new products by early adopters. Finally, standards set the minimum requirements for environmental, health and safety aspects and consequently promote trust especially in innovative products. Despite all these catalytic functions of standards for innovation, there are also shortcomings and problems. First, standards are the outcome of a consensus process of all interested parties and consequently represent the smallest denominator, which is often not a strong incentive for innovation activities, compared to more challenging technological specifications possibly set by governmental top-down regulations. Second, standards which are technology-specific and over-prescriptive instead of technologyneutral and focused on functionalities and performance characteristics do not create leeway and competitive incentives for alternative innovative solutions. Third, standards can also create lock-ins in existing technologies, especially if they do not specify interfaces or allow compatibility with follow-up technologies, because this hinders consecutive innovations in an industry. Especially proprietary standards of single or groups of dominant players may prevent competing technologies to market access and therefore thwart innovation. Blind, K. http://repub.eur.nl/res/pub/16236/ 2009-06-25T00:00:00Z Quite often transportation companies face two types of jobs, ones which they can plan themselves and ones which have to be done on call. In this paper we study the scheduling of these jobs, while we assume that job durations are known beforehand as well as windows in which the jobs need to be done. We develop several heuristics to solve the problem at hand. The most successful are based on defining an appropriate buffer. The methods are assessed in extensive experiments on two aspects, viz. efficiency, in the sense that they carry out many jobs and certainty, in the sense that they provide information beforehand about which jobs they will execute. Gabor, A.F. Dekker, R. Dijk, T. van Scheepstal, P. van http://repub.eur.nl/res/pub/15412/ 2009-04-07T00:00:00Z We address the value of RFID technology enabled information to manage perishables in the context of a supplier that sells a random lifetime product subject to stochastic demand and lost sales. The product's lifetime is largely determined by the time and temperature history in the supply chain. We compare two information cases to a Base case in which the product's time and temperature history is unknown and therefore its shelf life is uncertain. In the first information case, the time and temperature history is known and therefore the remaining shelf life is also known at the time of receipt. The second information case builds on the first case such that the supplier now has visibility up the supply chain to know the remaining shelf life of inventory available for replenishment. We formulate these three different cases as Markov decision processes, introduce well performing heuristics of more practical relevance, and evaluate the value of information through an extensive simulation using representative, real world supply chain parameters. Ketzenberg, M.E. Bloemhof-Ruwaard, J.M. http://repub.eur.nl/res/pub/15182/ 2009-03-12T00:00:00Z We propose a taxonomy of bibliometric indicators of scientific performance. The taxonomy relies on the property of consistency. The h-index is shown not to have this important property. Waltman, L.R. Eck, N.J.P. van http://repub.eur.nl/res/pub/15183/ 2009-03-12T00:00:00Z In this paper, we consider a make-to-stock production system with known exogenous replenishments and multiple customer classes. The objective is to maximize profit over the planning horizon by deciding whether to accept or reject a given order, in anticipation of more profitable future orders. What distinguishes this setup from classical airline revenue management problems is the explicit consideration of past and future replenishments and the integration of inventory holding and backlogging costs. If stock is on-hand, orders can be fulfilled immediately, backlogged or rejected. In shortage situations, orders can be either rejected or backlogged to be fulfilled from future arriving supply. The described decision problem occurs in many practical settings, notably in make-to-stock production systems, in which production planning is performed on a mid-term level, based on aggregated demand forecasts. In the short term, acceptance decisions about incoming orders are then made according to stock on-hand and scheduled production quantities. We model this problem as a stochastic dynamic program and characterize its optimal policy. It turns out that the optimal fulfillment policy has a relatively simple structure and is easy to implement. We evaluate this policy numerically and find that it systematically outperforms common current fulfillment policies, such as first-come-first-served and deterministic optimization. Quante, R. Fleischmann, M. Meyr, H. http://repub.eur.nl/res/pub/15029/ 2009-03-02T00:00:00Z This paper discusses how a manufacturer and its retailers interact with each other to optimize their product marketing strategies, platform product configuration and inventory policies in a VMI (Vendor Managed Inventory) supply chain. The manufacturer procures raw materials from multiple suppliers to produce a family of products sold to multiple retailers. Multiple types of products are substitutable each other to end customers. The manufacturer makes its decision on raw materials’ procurement, platform product configuration, product replenishment policies to retailers with VMI, price discount rate, and advertising investment to maximize its profit. Retailers in turn consider the optimal local advertising and retail price to maximize their profits. This problem is modeled as a dual simultaneous non-cooperative game (as a Nash game) model with two sub-games. One is between the retailers serving in competing retail markets and the other is between the manufacturer and the retailers. This paper combines analytical, iterative and GA (genetic algorithm) methods to develop a game solution algorithm to find the Nash equilibrium. A numerical example is conducted to test the proposed model and algorithm, and gain managerial implications. Yu, Y. Huang, G.Q. http://repub.eur.nl/res/pub/14521/ 2008-12-19T00:00:00Z Planning technology by itself is not sufficient to improve planning performance. What are the factors that determine the extent to which the benefits of planning technology are realized? In order to answer this question, this dissertation studies four mechanisms of fit between task and technology based on results both from the laboratory and a survey conducted in the Dutch transport sector. We specifically focus on the transport context as, on one hand algorithms supporting the planning task are extensively studied, and on the other hand, they are used in practice to a low extent. Apparently, task and technology do not fit. We contend that task-technology fit becomes more important as planning has to provide real-time services. Planners need technology that better fits their information processing, and algorithms need the assistance of the human planners to assess data reliability. Our results indicate that presentation can be used to increase adoption rates of above mentioned algorithms both for manual planning as well as for deliberative use of decision support. Providing functionality for collaborative optimization in addition to functionality for isolated optimization can further increase the extent to which planners make use of specialized planning technology. In addition, this thesis examines the human factor in planning, specifically the role of interdependence between planners, decision making style of planners and organizational structure. The practical implications of this dissertation are of interest mainly for managers in transport and transport software companies. The theoretical contribution relates to the field of Behavioral Operations Management. Krauth, E. http://repub.eur.nl/res/pub/14519/ 2008-12-15T00:00:00Z This thesis explores an under-researched field: humanitarian organizations and their supply chains. Humanitarian organizations respond to the basic needs of populations that experience a tragic disruption in their lives. Given the challenging contexts they operate in, this thesis first explores the factors that contribute to their performance. Thereafter, it identifies the strategies and organizational structures they need to adopt to respond to the growing challenge of attending to more people with fewer resources. It argues that to excel in disaster preparedness and response, among other things, humanitarian organizations need to engage in at least three partnership arrangements – temporary supply networks, a logistics coordination platform and a series of business and CSO partnerships – and build and strengthen a number of related capabilities. The invisible resource that once leveraged increases the opportunity and ability of a humanitarian organization to perform better is its social capital with parties involved in these partnership arrangements. In terms of lessons for business, it verifies the relevance and benefits of humanitarian partnership structures to commercial supply chains in specific scenarios. Apart from holding some lessons for humanitarian organizations themselves, this thesis contributes to the virtual organizing literature and provides empirical evidence for the emergence and management of logistics virtual organizations. Samii, R.