Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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    The analysis of plant root responses to nutrient concentration, soil volume and neighbour presence : Different statistical approaches reflect different underlying basic questions
    Chen, Bin J.W. ; During, Heinjo J. ; Vermeulen, Peter J. ; Kroon, Hans de; Poorter, Hendrik ; Anten, Niels P.R. - \ 2020
    Functional Ecology 34 (2020)10. - ISSN 0269-8463 - p. 2210 - 2217.
    game theory - neighbour detection - nutrient concentration - nutrient depletion - plant–plant interaction - pot-based experiment - root competition - soil volume

    To investigate the responses of plants to their below-ground neighbours independently of nutrient availability, experiments generally require a solitary treatment with one plant grown alone with one unit of nutrients, and a neighbour treatment with two plants grown together with two units of nutrients. This can either be done by doubling nutrient concentration (C) or by doubling soil volume (V) in the neighbour treatment as compared to the solitary treatment. Statistically analysing the same dataset from an experiment that grew plants in solitary or neighbour treatment with a series of V given a fixed amount of nutrients per plant (e.g. 1 g), Chen et al. (2015a) found significant neighbour effects when they controlled for V, while McNickle (2020) found the effects to be insignificant when he controlled for C. The discrepancy in the results of the two studies is caused by a difference in their analytical approaches. This includes (a) different choices of data transformation for the controlling factor, and (b) a mathematical deviation of model structures between V-based and C-based analyses, due to the different inversely proportional V-C relationships between solitary (Formula presented.) and neighbour (Formula presented.) treatments. Choices for either V or C as a controlling factor in the analyses for ‘neighbour effect’ are based on two different perspectives, focussing either on neighbour-induced nutrient depletion (like McNickle, 2020) or on identity recognition (like Chen et al., 2015a). We also raise concerns about the use of mesh-divided root interaction design and replacement series design in the studies of plant–plant root interactions. We propose to adjust the experimental designs and analytical methods based on the focal perspectives of neighbour effect.

    Plant-plant interactions mediate the plastic and genotypic response of Plantago asiatica to CO2 : An experiment with plant populations from naturally high CO2 areas
    Loon, Marloes P. Van; Rietkerk, Max ; Dekker, Stefan C. ; Hikosaka, Kouki ; Ueda, Miki U. ; Anten, Niels P.R. - \ 2016
    Annals of Botany 117 (2016)7. - ISSN 0305-7364 - p. 1197 - 1207.
    Canopy functioning - climate change - competition - elevated CO - evolutionary response - game theory - genotypic response - naturally high CO - plant-plant interactions - Plantago asiatica L. - plastic response - selection pressure

    Background and Aims The rising atmospheric CO2 concentration ([CO2]) is a ubiquitous selective force that may strongly impact species distribution and vegetation functioning. Plant-plant interactions could mediate the trajectory of vegetation responses to elevated [CO2], because some plants may benefit more from [CO2] elevation than others. The relative contribution of plastic (within the plant's lifetime) and genotypic (over several generations) responses to elevated [CO2] on plant performance was investigated and how these patterns are modified by plant-plant interactions was analysed. Methods Plantago asiatica seeds originating from natural CO2 springs and from ambient [CO2] sites were grown in mono stands of each one of the two origins as well as mixtures of both origins. In total, 1944 plants were grown in [CO2]-controlled walk-in climate rooms, under a [CO2] of 270, 450 and 750 ppm. A model was used for upscaling from leaf to whole-plant photosynthesis and for quantifying the influence of plastic and genotypic responses. Key Results It was shown that changes in canopy photosynthesis, specific leaf area (SLA) and stomatal conductance in response to changes in growth [CO2] were mainly determined by plastic and not by genotypic responses. We further found that plants originating from high [CO2] habitats performed better in terms of whole-plant photosynthesis, biomass and leaf area, than those from ambient [CO2] habitats at elevated [CO2] only when both genotypes competed. Similarly, plants from ambient [CO2] habitats performed better at low [CO2], also only when both genotypes competed. No difference in performance was found in mono stands. Conclusion The results indicate that natural selection under increasing [CO2] will be mainly driven by competitive interactions. This supports the notion that plant-plant interactions have an important influence on future vegetation functioning and species distribution. Furthermore, plant performance was mainly driven by plastic and not by genotypic responses to changes in atmospheric [CO2].

    Verkennen en toepassen van besluitvormingsmodellen in de uitvoering van natuurbeleid
    Verburg, R.W. ; Westerhof, E.J.G.M. ; Bogaardt, M.J. ; Selnes, T. - \ 2012
    Wageningen : Wettelijke Onderzoekstaken Natuur & Milieu (WOt-werkdocument 319) - 79
    natuurbeleid - besluitvorming - speltheorie - analytische methoden - nature conservation policy - decision making - game theory - analytical methods
    In dit werkdocument is een literatuurverkenning uitgevoerd van verschillende bestuurskundige analysemethoden en besluitvormingsmodellen. Daarnaast zijn twee casussen onderzocht om te verkennen of dergelijke casussen toepasbaar zijn om besluitvormingsmodellen in het natuurbeleid te simuleren. Uit de verkenningen is een prototype besluitvormingsmodel ontwikkeld en is de besluitvorming van een casus gesimuleerd. De voorlopige resultaten van deze simulaties geven aanleiding om het besluitvormingsmodel verder te ontwikkelen.
    Emergent Results of Artificial Economics
    Osinga, S.A. ; Hofstede, G.J. ; Verwaart, T. - \ 2011
    Heidelberg : Springer Verlag (Lecture Notes in Economics and Mathematical Systems 652) - ISBN 9783642211072
    economie - bedrijfswetenschap - speltheorie - wiskunde - computertechnieken - sociale wetenschappen - economics - management science - game theory - mathematics - computer techniques - social sciences
    The Role of Proactive Adaptation in International Climate Change Mitigation Agreements
    Bruin, K.C. de; Weikard, H.P. ; Dellink, R.B. - \ 2011
    Umea, Sweden : CERE
    klimaatverandering - klimaatadaptatie - internationale verdragen - speltheorie - climatic change - climate adaptation - international agreements - game theory
    This paper investigates the role of proactive adaptation in international mitigation coalition formation. Adaptation is introduced into a three stage cartel game of coalition formation. We analytically derive the optimal level of mitigation and proactive adaptation for the singletons and coalition members. We introduce the AD-STACO model which is constructed based on the STACO model, which is an applied three-stage cartel formation model with 12 heterogenous regions.
    Incentives in the water chain: wastewater treatment and reuse in developing countries
    Gengenbach, M.F. - \ 2010
    Wageningen University. Promotor(en): Ekko van Ierland, co-promotor(en): Hans-Peter Weikard. - [S.l. : S.n. - ISBN 9789085857655 - 131
    afvalwater - afvalwaterbehandeling - hergebruik van water - waterbeheer - stimulansen - wiskundige modellen - speltheorie - sociaal welzijn - ontwikkelingslanden - integraal waterbeheer - waste water - waste water treatment - water reuse - water management - incentives - mathematical models - game theory - social welfare - developing countries - integrated water management
    The proper management of wastewater and its reuse is crucial in order to reduce hazards and maintain a variety of benefits. The merits of improvements in wastewater management are particularly high where effective wastewater treatment is not in place and completely untreated wastewater is reused. This setting applies to many developing countries. There is a need to study the trade-off between benefits and costs of the use of wastewater to establish efficient water management. Moreover, successful water management needs to take the individual incentives of stakeholders into account. The general objective of this thesis is to study how economic incentives of stakeholders determine welfare along the water chain of use, treatment and reuse and how these incentives can be regulated in order to maximize welfare. This thesis identifies four characteristic settings in which either asymmetric information or externalities cause welfare losses, at least in the absence of regulation. For each setting the thesis develops a game theoretic model that can be used to design incentive schemes that govern the generation, treatment, and reuse of wastewater in developing countries such that the highest possible welfare is obtained.
    Game-theoretic analysis of international climate agreements: the design of transfer schemes and the role of technological change
    Nagashima, M.N. - \ 2010
    Wageningen University. Promotor(en): Ekko van Ierland, co-promotor(en): R.B. Dellink; Hans-Peter Weikard. - [S.l.] : S.n. - ISBN 9789085856078 - 145
    klimatologie - klimaatverandering - internationale verdragen - internationale samenwerking - speltheorie - besluitvorming - technologieoverdracht - modellen - opwarming van de aarde - milieubeleid - climatology - climatic change - international agreements - international cooperation - game theory - decision making - technology transfer - models - global warming - environmental policy
    Global warming is one of the crucial challenges that the world is facing now. The allocation of
    reduction efforts among regions has long been negotiated and it will not be an easy task to achieve a
    full cooperation with stringent targets.
    The thesis examines the formation of international climate agreements (ICAs) in a game-theoretic
    framework. I analyse strategic behaviour of a number of regions to reduce greenhouse gas (GHG)
    emissions. Game-theoretic approaches have been widely used to examine an interaction between
    countries in the negotiations on climate change, and have emphasised difficulties in designing such a
    voluntary agreement. This thesis provides a systematic approach to examine the impacts of designs of
    the ICAs on the success of ICAs.
    In Chapter 2, I present the basic structure of the STACO-2.1 model, composed of a game-theoretic
    framework and applied features, with specifications and calibrations of the functions used in the
    model. I analyse the results for (i) the All Singletons coalition structure, (ii) the Grand coalition
    structure, and (iii) all stable coalition structures. This case can serve as a suitable reference point for
    the analysis of the various mechanisms in the following chapters. The results show that a coalition of
    EU15 and Japan is stable. Both regions have an interest in cooperation, because of their higher
    marginal benefits from abatement. The results suggest that regions with relatively lower marginal
    abatement costs and lower marginal benefits would be worse off when they cooperate as they bear the
    largest burden of abatement but obtain the least benefits. This suggests that transfer schemes can be
    effective to stabilise larger coalitions.
    In Chapter 3, I analyse the impact of pragmatic and optimal transfer schemes on the incentives for
    regions to join international climate agreements. With an applied model that comprises twelve world
    regions I investigate: (i) a benchmark without transfers, (ii) scenarios with allocation-based rules
    where coalition members receive tradable emission permits proportional to initial or future emissions,
    (iii) scenarios with outcome-based rules where the coalition surplus is distributed proportional to the
    emissions, and (iv) a scenario based on an optimal sharing rule where the coalition surplus is
    distributed proportional to outside option payoffs.
    I find that when the transfer scheme is poorly designed in the sense that it increases incentives to
    free-ride, the best performing stable coalition may be worse than in the case of no transfers. In our
    applied setting this occurs for the initial-emissions-based tradable permit system (grandfathering).
    Improvements of the initial-emissions-based tradable permit system, such as a tradable permit system
    based on the full path of emissions or a surplus sharing scheme, do enhance stability of coalitions. For
    the optimal transfer scheme we find that larger coalitions, which include key players such as the
    United States and China, can be stable, but no transfer scheme is capable of stabilising the Grand
    Coalition. The results show that optimal transfers perform much better than more pragmatic transfer
    schemes. Such schemes, however, require detailed insight into the incentive structures of the regions.
    Therefore, there is a trade-off between more pragmatic schemes that may be easier to implement but
    are hardly effective and optimal transfers which may be hard to achieve in actual negotiations.
    In Chapter 4, I explore how different technology spillover mechanisms among regions can
    influence the incentives to join and stabilise an international agreement. Several theories on the impact
    of technology spillovers are evaluated by simulating a range of alternative specifications: (i) no
    spillovers, (ii) internal spillovers, (iii) global spillovers, (iv) coalitional spillovers, and (v) extended
    spillovers (all possible technology spillovers).
    I find that spillovers are a good instrument to increase the abatement efforts of coalitions and
    reduce the associated costs. In our setting, however, they cannot overcome the strong free-rider
    incentives that are present in larger coalitions. Therefore, technology spillovers do not substantially
    increase the success of international environmental agreements. This conclusion is robust with respect
    to the specification of technology spillovers.
    In Chapter 5, I relax the assumption of exogenous technological change analysed in the previous
    chapters and explore the impacts of induced technological change (ITC) on the stability of an
    international climate agreement. To examine the impacts of different specifications of technological
    change in reducing abatement costs on regional incentives, three scenarios are investigated: (i) no
    technological change (noTC), (ii) exogenous technological change (ExTC), and (iii) induced
    technological change (ITC). Technological change is induced by the abatement targets. It reduces
    emissions through regional R&D investments, which lowers abatement costs over time. The results
    reveal that the set of best-performing stable coalitions and the associated indicator of success hardly
    change between the scenario of noTC and ExTC, but ITC does produce a different set of stable
    coalitions. Coalitions that are stable in all three scenarios can achieve the highest NPV of payoffs in
    the case of ITC. The results indicate that coalition members increase their investments and abatement
    substantially when they cooperate in the case of ITC. As a result of increased global abatement, not
    only coalition members but also singletons obtain high benefits, which leads to decrease (increase) in
    the number of internally (externally) stable coalitions. Therefore, ITC might improve global payoffs,
    however, at the same time it tends to increase free-rider incentives due to the public good nature of
    global warming. I find that the indicator of success is quite robust with respect to the productivity of
    R&D. Furthermore, the number of internally (externally) stable coalitions decreases (increases) with
    the value of the productivity of R&D, as free-riding incentives increase. I find that stability is sensitive
    with respect to changes of the discount rate. The number of stable coalitions increases with the value
    of discount rate. In both cases, the dominating mechanism is that higher productivity of R&D or a
    lower discount rate increase the payoffs of regions, and thus increase the gains of cooperation, but also
    increase free-rider incentives.
    Overall, the main finding of this thesis is that well-designed mechanisms can facilitate successful
    formation of partial coalitions, although global cooperation is still hard to achieve. The reason lies in
    the public good nature of global warming and regional characteristics of benefits and costs. Following
    insights of the current literature on transfer schemes, our systematic analysis supports the fact that an
    incentive to join the agreement is highly sensitive to the design of transfers. For different designs of
    transfer schemes, there is a trade-off between feasibility and effectiveness. Allocation-based transfer
    schemes are easier to implement than an optimal transfer scheme which can achieve more successful
    coalition formation in the context of global payoffs and CO2 emissions.
    The role of technological change has received significant attentions to reduce a significant amount
    of emissions. Two types of sources of technological change are investigated in the thesis: (i)
    technology spillovers and (ii) R&D investment. If technology spillovers are treated as private goods, a
    country with higher abatement technology can be an attractive partner for other countries to cooperate
    with, as cooperation on abatement will lead to reduction in abatement costs without paying for
    technology improvement. Within the context of assumptions used here, quantitative results suggest
    that the spillovers between cooperating regions may not be effective enough to overcome the freeriding
    incentives for non-cooperative countries, as large emission reduction by cooperating countries
    will bring large benefits also to non-cooperating countries.
    In the case of induced technological change, regional R&D investments improve the stock of
    knowledge which leads to low abatement costs. When cooperating with other regions, signatories can
    obtain higher payoffs than in All Singletons, which is driven by increased investment after cooperation
    on abatement. ITC plays a significant role in increasing global payoffs, however, it also increases freerider
    incentives as non-signatories also benefit from a large reduction made by signatories. As long as
    R&D investments increase payoffs under cooperation on abatement and the gains from cooperation
    are large, the difference in the source of technological change will not provide any significant
    differences in terms of improvement in the success of a climate agreement.
    The Kyoto Protocol was the first significant step that provided stimulus for search for successful
    international cooperation on climate change policies, although there are issues to be improved. Now,
    negotiation on the post Kyoto framework has been taking place with an aim of large cooperation on
    tackling climate change among countries. Flexible measures which lead to a win-win cooperation for
    the countries involved will continue to play a crucial role in achieving a successful cooperation and the
    search for well-designed mechanisms will be further pursued.
    Game-theoretic models of water allocation in transboundary river basins
    Ansink, E.J.H. - \ 2009
    Wageningen University. Promotor(en): Ekko van Ierland, co-promotor(en): Arjan Ruijs; Hans-Peter Weikard. - [S.l. : S.n. - ISBN 9789085854395 - 164
    watertoewijzing - waterbeheer - beheer van waterbekkens - rivieren - speltheorie - afvoer - rivierafvoer - internationale verdragen - grensoverschrijdend gebied - water allocation - water management - watershed management - rivers - game theory - discharge - stream flow - international agreements - transboundaries
    Onderzoeksvragen zijn hoe samenwerking in waterverdeling kan worden verbeterd, en hoe internationale verdragen zo kunnen worden ontworpen dat ze niet worden verbroken. Onderliggende onderwerpen zijn de aanwezigheid van betwiste eigendomsrechten op water en het ontwerp van aantrekkelijke verdeelregels voor rivierwater. Het doel van dit proefschrift is het analyseren van waterverdeling in grensoverschrijdende rivieren met behulp van speltheoretische modellen. Dit type modellen is geschikt voor het analyseren van strategische interactie tussen landen die een rivier delen, in hun beslissingen omtrent watergebruik.
    The organisation of transactions : studying supply networkd using gaming simulation
    Meijer, S.A. - \ 2009
    Wageningen University. Promotor(en): Onno Omta; George Beers, co-promotor(en): Gert Jan Hofstede. - [S.l.] : S.n. - ISBN 9789085853343 - 211
    bedrijfsvoering - speltheorie - ketenmanagement - netwerken - spelsimulatie - agro-industriële ketens - institutionele economie - management - game theory - supply chain management - networks - gaming simulation - agro-industrial chains - institutional economics
    This book studies the organisation of transactions in supply networks. More specifically it investigates the influence of social structure on the mode of organisation in supply networks. To gain new insights, the results in this book have been gathered using gaming simulation as a research method. As this is a new application of gaming simulation, special attention is paid to the methodological implications.
    Food supply chains and networks span a whole series of firms from grower to consumer. Depending on the product traded and the market in which it is consumed the grower and consumer can be located in countries thousands of kilometres apart. However, the food still needs to arrive in a perfect condition at the consumer, passing through several companies in the supply network. Transactions need to be made between the subsequent companies that trade the product. The way in which the transactions are organised can be any mix of three modes of organisation, namely market, network and hierarchy. This book concentrates on market and network. The market mechanism uses the price as a control mechanism. Network uses trust and reputation for this.
    Transactions are made by people. People who trade with each other may have known one another for a long time. Their companies may have business ties. And the traders will have certain norms and values about what is appropriate behaviour in trade. The interpersonal relations, business ties and norms and values influence trade behaviour in a supply network. This behaviour will influence the mode of organisation of the network. Lazzarini et al (2001) call this social structure, as a bucket category of variables from the social sciences that explain interpersonal and business relations and the norms and values of the supply network as a whole. Trust between traders is the most prominent interpersonal variable. Business relations are expressed in a level of embeddedness as a measure of the density and the strength of ties between businesses. Norms and values in a network can be related to the culture traders come from. Social structure covers a broad range of concepts from sociology to social psychology and network theory. This book focuses on the major variables trust and embeddedness, with norms and values as an important context.
    Gaming simulation is commonly used as a training or learning tool. This book, however, uses gaming simulation as a research method. The methodological contribution of this book is to use gaming simulation as a lab environment to generate and test hypotheses using both qualitative and quantitative data in the domain of supply chains and networks. Chapter 2 discusses the methodological issues of gaming simulation as a research method. The first section (2.1) describes what gaming simulation is and gives 6 inputs for a session with a gaming simulation. Section 2.2 argues that by using gaming simulation, researchers can study the behaviour of real people playing a role of interest for research in a simulated environment, based upon the characteristics of gaming simulation. Research purposes are less common among gamers. Section 2.3 first describes the non-research purposes, while Section 2.4 discusses the purposes for research. Three types of research purpose are distinguished, namely hypothesis generation, hypothesis testing and sensitivity analysis when combined with multi-agent simulation. Research with gaming simulation is often positioned in the design sciences, which means that the effect of the gaming simulation as a design on changes in the real world is tested. This book positions gaming simulation in the analytical sciences, to study phenomena in the real world.
    Section 2.5 positions gaming simulation among other research methods common in the domain of supply chains and networks. The influence of social structure on the organisation of transactions can be studied in a single or small set of supply networks using case studies, to provide in-depth observations of actions and the surrounding context. The generalisability of detailed case studies is a complicated matter. Furthermore, it is hard to observe the actual actions in a case study research. Questionnaire research overcomes the generalisability issue of case studies, though lacks the in-depth knowledge of a subject within its contextual variables. Surveys do not observe actual actions either.
    The validity and reliability of gaming simulation is discussed in Section 2.6 and is based on the work of Raser (1969) who identified four criteria for validity: psychological reality, process, structural and predictive validity. Each of the four criteria has been used in this book.
    Chapter 3 presents the research method used in this study. It consists of four interconnected cycles. The first is the design cycle in which the gaming simulation is developed and tested. The test sessions provide insight into the structure and important variables of the problem studied. The hypothesis generation function can be done using the design cycle. The outcomes of the design cycle are induced hypotheses (based upon the test sessions) and the gaming simulation. Both are inputs for the empirical cycle in which a structured experimental set-up results in game sessions, which provide the data to be analysed.
    The other two cycles are support cycles. The first is the multi-agent design cycle in which a multi-agent version of the gaming simulation is built. The second one is the multi-agent simulation cycle in which experiments can be conducted to verify the multi-agent model or to draw conclusions. Multi-agent simulation could in the future provide ways to select interesting variable settings to play with human participants. The multi-agent simulation is validated against conclusions from the empirical cycle.
    Chapter 4 discusses the reference theories on which this book is based. Section 4.1 presents theories on supply chains and networks needed for the domain of study. Section 4.2 discusses new institutional economics used as the main theoretical framework for analysis of the results of the two gaming simulations. Central elements are the four-level framework by Williamson (2000) that links levels of analysis from culture to day-to-day operations, and the modes of organisation, namely network, market and hierarchy. Section 4.3 discusses the fact that there are other explanatory theories used for the two specific gaming simulations. These theories are discussed in the subsequent chapters.
    Two custom-built gaming simulations each study an aspect of the influence of social structure on the mode of organisation of transactions. Chapter 5 presents the first one, called the Trust and Tracing Game (TTG). The TTG assessed the influence of trust and embeddedness on the choice between the network and the market mode of organisation. The TTG is a paper-based gaming simulation of a supply network of a product with a hidden quality attribute. Participants face the dilemma of whether to rely on trust or tracing when confronted with a possible cheat. Section 5.1 describes the fact that the TTG was originally designed to be a learning tool by the researchers who started this project. The TTG operationalised an abstract supply network of a good with a hidden quality attribute. Hypotheses were generated during the last series of test sessions in the design cycle. From observations of 15 test sessions, intended to identify the learning effect, conclusions about the participants’ behaviour in the sessions were drawn. The results showed that participants used the two modes of organisation, both the network and the market mechanism.
    Section 5.2 uses the observations and variables identified in 5.1 as inputs to the empirical cycle for the quantitative analysis of 27 additional sessions as induced hypotheses and list of variables to be collected. The quantitative analysis proved that the mode of organisation in the Trust and Tracing Game was network for the financially well-performing traders and market for the well-performing consumers. Social structure manifested itself in trust and embeddedness influencing the organisation of transactions. Generally trust and embeddedness were detrimental to the (financial) performance in the setting of the Trust and Tracing Game, as the traders who benefitted from the use of network exploited their trusting clients. There was no evidence that trust affected the measurable transaction costs. Additional analyses showed that buyers detected cheats with other mechanisms than tracing. The traces showed more cheats than statistically possible when the envelopes were a random sample.
    Section 5.3 presents the multi-agent model developed for the Trust and Tracing Game. This model has been tested and validated. It has been possible to validate the multi-agent simulation on an aggregate level against sessions with human participants. Hypotheses were formulated based upon observations of sessions. Each hypothesis could be confirmed in model runs.
    Chapter 6 presents research with the second gaming simulation, called the Mango Chain Game (MCG). It was developed to study the bargaining power and revenue distribution among traders in the Costa Rican mango export chain. The MCG assessed what factors, including social structure, determined the bargaining power, what mode of organisation was used and how this influenced the revenue distribution between traders. The data collection combined data from a questionnaire among the participants with the actual behaviour in the game session. Five sessions were conducted with smallholders in the Costa Rica lowlands, resulting in 82 contracts. The results show that the bargaining power in the sessions was isomorphic to the real-world bargaining power of smallholders, multinationals and independent exporters. As expected, lower bargaining power on the part of the buyer (seller) resulted in higher revenue for the seller (buyer). In general, stakeholders with more bargaining power were able to take advantage of the other agents. Higher risk-aversion of the buyers and/or the sellers led to higher revenues for the other agents involved in the exchange relationship. In the same vein, long-term contracts in the buyer-seller relationship led to lower revenues (but also reduced risk) for sellers. The latter result was surprising, since contract choice appeared only to be significant for the seller’s and not for the buyer’s revenue equation. Mango producers turned out to be well aware of the fact that the type of markets in which they operate is mainly based on short-terms contracts. Not working with long-term contracts gave them the opportunity to remain flexible towards changes in demand and supply that they cannot control. Producers were trying to establish long-term relationships, but they could equally rely on repeat short-term contracts with the same partner. The latter type of contract tends to rely on trust or friendship, thus the network mode of organisation is at play here. Finally, real-world wealth appeared to have a significant impact on bargaining power.
    Chapter 7 discusses the experiences with gaming simulation as a research method and draws conclusions from the combined results of the TTG and MCG. Section 7.1 discusses the experiences with gaming simulation to generate and test hypotheses. Methodologically there were some differences. Research with the TTG took more time than that with the MCG. The reasons for this difference can be found in the functions used and the number of variables. The TTG started with a broad scope, where the important variables coming from all four levels of the Williamson framework had yet to be found in the design cycle. In contrast to this, the MCG used an analytical model with fewer and theory-based variables. Attention is paid to validity and reliability. In summary, the process validity of both gaming simulations was the most important aspect, and psychological reality was required to get the process going. Both the TTG and MCG met these criteria in different ways. The MCG scored more positively on both the structural and predictive validity because of the closer resemblance of the supply network modelled with the real world and the use of real smallholders versus students. Care should be taken regarding claims about what is modelled.
    The multi-agent simulation has been developed to perform sensitivity analyses of variable settings (loads). This project has not reached the point where variable settings selected with the MAS have been tested in a human session. Future research should make clear whether MAS really helps to increase efficiency by reducing the number of sessions needed through selection of interesting loads. This project has proven, however, that it is possible to develop and validate a multi-agent model of a gaming simulation.
    The different types of data that the TTG and MCG can generate are hard to obtain using other methods. Gaming simulation is special in that the participants are exposed to a laboratory-like situation that isolates them from the real-world (trading) environment. In this laboratory environment, the attention of the participants can be focused on a particular problem, while retaining the full richness of human behaviour. Based upon the experiences presented in this book, gaming simulation can be positioned as a research method that facilitates a whole range of data collections. It is possible to acquire data before, during and after a session, enabling the coupling with questionnaires and interviews and actual observation of actions. It can analyse differences between participants in one session, testing for differences in backgrounds, or between session, testing for the effects of varying the load and situation in a session, or even the rules, roles, objectives and constraints of the gaming simulation itself. The combination of qualitative and quantitative analyses that is possible using gaming simulations makes the method a good candidate for research that requires both. In the methodology used in the MCG and TTG the first cycle (design cycle) was based upon a qualitative approach, while the hypotheses were tested in a quantitative empirical cycle.
    Section 7.2 compares the theoretical conclusions of the Trust and Tracing Game with those of the Mango Chain Game and relates them to the main research question. The conclusions of the MCG are in line with the TTG conclusions insofar as the variables of social structure used in this book (trust, embeddedness, norms and values) clearly shape the organisation of the transactions. Both the TTG and MCG show that trust and embeddedness lead to the use of the network mode of organisation, but also to less revenue in the setting of these two gaming simulations. It seems that the network mechanism is essential in supply networks with independent traders but not in a way that directly leads to more revenues. The conclusions from the two gaming simulations are at odds with the leading paradigm in the literature on supply networks which says that trust and relationships are important for successful business. The conclusions are more in line with neo-classical economic theory, where companies use transactions as the rational result of considering price and product.
    Section 7.3 presents ideas for future research divided into ideas for the domain and ideas for methodological improvements. Next, Section 7.4 presents the implications of the research for the domain of food supply chains and networks. The application of gaming simulation as (one of the) research method(s) can be of value for gathering data about the real behaviour of real participants in a simplified ‘surrogate’ environment, determined by the gaming simulation. In this book a laboratory for chain and network studies has been built. Section 7.5 looks at the implications for other domains and argues that the issues about trust, embeddedness and other variables from social structure can be found in most other business domains, thus providing opportunities for research with this method.
    The chapter ends with some concluding remarks in Section 7.6, stating that this book showed as a proof-of-principle that gaming simulation is an excellent additional research method for controlled analysis of complex social systems. It also showed that the possibility to have a repeatable experiment within a controlled contextual setting provides insight into socio-economic behaviour in a way that can be approached from multiple bodies of theory. Staying within the framework of one body of theory cannot explain the full richness of human behaviour, thus links have to be made. In the current book the theoretical framework from new institutional economics has been used and some first attempts have been made to link up with theory on culture, psychology and other theories in the social sciences. Future research could use gaming simulation as the research method of choice for true interdisciplinary research.

    Nederlandse samenvatting
    Dit boek bestudeert de organisatie van transacties, en in het bijzonder de invloed van ‘social structure’ op keuze van het organisatiemechanisme in een handelsnetwerk. De resultaten in dit boek zijn verkregen met behulp van spelsimulatie als onderzoeksmethode. Dit is een nieuwe toepassing van spelsimulatie en daarom besteedt dit boek bijzondere aandacht aan de methodologische aspecten.
    Handelsnetwerken in voedingswaren bestrijken een hele rij van bedrijven tussen de boer en de consument. De boer en de consument kunnen duizenden kilometers van elkaar verwijderd zijn, afhankelijk van het soort product en de markt waarin het wordt geconsumeerd. Hoe ver ook, het voedsel moet in perfecte conditie bij de klant aankomen, terwijl het door de handen van vele bedrijven gaat. Deze bedrijven moeten met elkaar transacties sluiten. De manier waarop deze transacties worden georganiseerd is een mix van drie organisatiemechanismen, te weten markt, netwerk en hiërarchie. Dit book concentreert zich op het markt- en het netwerkmechanisme. Het marktmechanisme gebruikt de prijs als als sturingselement terwijl het netwerkmechanisme vertrouwen en reputatie gebruikt.
    Mensen maken transacties. Mensen die handel met elkaar drijven kunnen elkaar soms al heel lang kennen. Hun bedrijven kunnen banden hebben, en de handelaren zullen bepaalde normen en waarden hebben over wat fatsoenlijk gedrag is in handel. De persoonlijke relaties, zakelijke banden en de normen en waarden beïnvloeden het handelsgedrag in een handelsketen. Dit gedrag heeft invloed op de mix van organisatiemechanismen. Lazzarini et al (2001) noemen dit de sociale structuur, wat een verzamel-categorie is voor allerlei variabelen uit de sociale wetenschappen over persoonlijke relaties, zakelijke banden en de normen en waarden van het gehele handelsnetwerk. Vertrouwen tussen handelspartners is de belangrijkste persoonlijke variabele. Zakelijke banden worden uitgedrukt in een niveau van ‘embeddedness’, een begrip wat betekent in hoeverre een bedrijf banden heeft en hoe sterk die banden zijn. De normen en waarden in een handelsnetwerk kunnen gerelateerd zijn aan de cultuur waar de handelaren vandaan komen. Sociale structuur bestrijkt een heel scala van concepten komend van onder andere van sociale psychologie en netwerk theorie. Dit boek concentreert zich op de belangrijkste variabelen vertrouwen, embeddedness, waarbij normen en waarden een belangrijke context vormen.
    Spelsimulatie is een bekende methode om te trainen. In dit boek wordt spelsimulatie echter gebruikt als onderzoeksmethode. De methodologische bijdrage ligt in het gebruik van spelsimulatie als een laboratoriumomgeving om hypotheses te genereren en te testen met zowel kwalitatieve als kwantitatieve data in het domein van handelsnetwerken. Hoofdstuk 2 behandelt de methodologische implicaties van spelsimulatie als onderzoeksmethode. Sectie 2.1 beschrijft wat spelsimulatie is en geeft 6 ingrediënten voor een spelsessie. Sectie 2.2 beargumenteert dat onderzoekers het gedrag van echte mensen die een rol spelen in een gesimuleerde omgeving kunnen bestuderen met spelsimulatie. Een minderheid van de gebruikers van spelsimulatie gebruikt de methode voor onderzoek. Sectie 2.3 behandelt het nut van spelsimulatie voor niet-onderzoeksdoeleinden, waarna Sectie 2.4 het nut voor onderzoeksdoeleinden bediscussieerd. Drie soorten functies worden hierin onderscheiden, te weten het genereren van hypotheses, het testen van hypotheses en gevoeligheidsanalyse in combinatie met een multi agent simulatie. Onderzoek met behulp van spelsimulatie wordt vaak gepositioneerd in de ontwerpwetenschappen, wat inhoudt dat het effect van het ontwerp (de spelsimulatie) op de echte wereld wordt getest. In dit boek wordt spelsimulatie in de analytische wetenschappen geplaatst, die fenomenen in de echte wereld bestuderen.
    Sectie 2.5 bespreekt de positie van spelsimulatie ten opzichte van meer gebruikelijke onderzoeksmethoden in het domein van handelsnetwerken. De invloed van sociale structuur op de mix can organisatiemechanismen kan worden bestudeerd door 1 of enkele handelsnetwerken te bestuderen in een casus studie om diepgaande observaties van handelingen en de context te verkrijgen. De generaliseerbaarheid van gedetailleerde casus studies is een gecompliceerde zaak. Ook is het moeilijk om echte handelingen te observeren in een casus studie, omdat meestal alleen de vastlegging van de handeling te volgen is. Vragenlijsten hebben geen problemen met generaliseerbaarheid maar missen de gedetailleerde kennis over een onderwerp van studie in zijn context. Vragenlijsten observeren ook geen handelingen.
    De validiteit en betrouwbaarheid van spelsimulatie wordt in Sectie 2.6 behandeld, gebaseerd op het werk van Raser (1969) die vier criteria voor validiteit identificeerde, namelijk psychologische realiteit, proces-, structuur- en voorspellende validiteit. Ieder van deze criteria wordt in dit boek gebruikt.
    Hoofdstuk 3 presenteert de onderzoeksmethode zoals gebruikt in deze studie. Het bestaat uit vier cycli die onderling zijn verbonden. De eerste cyclus is de ontwerp cyclus waarin de spelsimulatie wordt ontwikkeld en getest. De test sessies geven inzicht in de structuur en belangrijke variabelen van het onderzoeksprobleem. De hypothese genererende functie kan in de ontwerpcyclus worden gedaan. De uitkomsten van de ontwerpcyclus zijn geïnduceerde hypothesen (gebaseerd op de test sessies) en de ontworpen spelsimulatie. Beide zijn ingrediënten voor de empirische cyclus waarin een gestructureerde experimentele configuratie resulteert in spelsessies die weer de data opleveren voor de analyse.
    De andere twee cycli zijn ondersteunend. De eerste is de multi-agent ontwerpcyclus waarin een multi-agent versie van de spelsimulatie wordt ontworpen. De tweede is de multi-agent simulatie cyclus waarin experimenten worden gedaan om het multi-agent model te valideren of om conclusies te kunnen trekken. Multi-agent simulaties kunnen in de toekomst manieren verschaffen om interesante configuraties van variabelen te selecteren die daarna met echte mensen worden gespeeld in spelsessies. De multi-agent simulatie is gevalideerd tegen conclusies uit de empirische cyclus.
    Hoofdstuk 4 bediscussieert de referentie-theorieën waarop dit boek is gebaseerd. Sectie 4.1 presenteert theorieën over handelsketens en handelsnetwerken vanwege het domein van studie. Sectie 4.2 behandelt nieuwe institutionele economie wat hier gebruikt wordt als belangrijkste theoretische raamwerk voor de analyse van de resultaten van de twee spelsimulaties. Centrale elementen zijn het vier-lagen model van Williamson (2000) dat de niveaus van analyse van cultuur tot en met dagelijkse operaties aan elkaar verbindt, en de organisatiemechanismen netwerk, markt en hiërarchie. Sectie 4.3 verklaart dat er zijn meer verklarende theorieën in gebruik zijn voor de twee spelsimulaties. Deze theorieën worden behandeld in de successievelijke hoofdstukken.
    Twee spelsimulaties bestuderen ieder een aspect van de invloed van sociale structuur op de mix van organisatiemechanismen. Hoofdstuk 5 presenteert de eerste, genaamd Trust and Tracing Game (TTG). De TTG bestudeert de invloed van vertrouwen en embeddedness op de keuze tussen het markt- en het netwerk-organisatiemechanisme. De TTG is een papieren spelsimulatie van een handelsketen in een product met een verborgen kwaliteitskenmerk. Deelnemers worden geconfronteerd met het dilemma of ze moeten uitgaan van vertrouwen of moeten tracen wanneer ze mogelijk bedrog signaleren. Sectie 5.1 beschrijft dat de TTG oorspronkelijk was ontworpen als leermiddel door de onderzoekers die dit project zijn gestart. Vanuit observaties van 15 testsessies, bedoeld om de leereffecten te bepalen, konden conclusies worden getrokken over het gedrag van de deelnemers in de spelsessies. De resultaten laten zien dat de deelnemers zowel het netwerk- als het markt-organisatiemechanisme gebruikten.
    Sectie 5.2 gebruikt de observaties en belangrijke variabelen uit Sectie 5.1 als ingrediënten voor de empirische cyclus voor de kwantitatieve analyse van 27 additionele sessies als geïnduceerde hypothesen en lijst van variabelen om te verzamelen. De kwantitatieve analyse bewees dat het netwerk-organisatiemechanisme werd gebruikt door financieel goed presterende handelaren en dat goed presterende consumenten het marktmechanisme gebruikten. Sociale structuur kwam naar voren door de invloed van vertrouwen en embeddedness op het gebruik van de organisatiemechanismen. Over het algemeen waren vertrouwen en embeddedness slecht voor de financiële resultaten binnen de omstandigheden van de TTG, omdat handelaren die profiteerden van het netwerkmechanisme hun goed-vertrouwende klanten exploiteerden. Een effect van vertrouwen op de (meetbare) transactiekosten werd niet gevonden. Aanvullende analyses lieten zien dat er andere manieren dan tracing moeten zijn waardoor bedrog wordt gedetecteerd. De keren dat er getraced werd vonden namelijk vaker een bedrog dan statistisch gezien mogelijk was.
    Sectie 5.3 presenteert het multi-agent model dat is ontworpen voor de TTG/ Dit model is getest en gevalideerd. Het is mogelijk gebleken om het multi-agent model te valideren op geaggregeerd niveau tegen sessies met menselijke deelnemers. Op basis van observaties zijn hypotheses geformuleerd die stuk voor stuk konden worden bevestigd in model-ronden.
    Hoofdstuk 6 presenteert onderzoek met de tweede spelsimulatie genaamd de Mango Chain Game (MCG). Dit spel is ontwikkeld om de onderhandelingsmacht en verdeling van opbrengsten tussen handelaren in het Costaricaanse mango exportnetwerk te bestuderen. De MCG bekeek welke factoren, waaronder sociale structuur, de onderhandelingsmacht bepaalden, welk organisatiemechanisme gebruikt werd en hoe dit de verdeling van de opbrengsten tussen handelaren beïnvloedde. De dataverzameling combineerde gegevens uit een vragenlijst met het gedrag in de sessies. Vijf sessies zijn georganiseerd met mangoboeren in de Costaricaanse laaglanden, resulterend in 82 contracten. De resultaten laten zien dat onderhandelingsmacht in de spelsessies gelijkvormig was met die in de echte wereld. Zoals verwacht resulteerde een lagere onderhandelingsmacht van de koper in hogere opbrengsten voor de verkoper en vice versa. Over het algemeen waren deelnemers met meer onderhandelingsmacht in staat om voordeel te behalen uit andere deelnemers. Een hogere weerstand tegen risico van een koper of verkoper leidde tot meer opbrengsten voor de handelspartner. Parallel hieraan gaven lange-termijn contracten minder opbrengsten (maar ook minder risico) voor de verkopers. Dit laatste resultaat was opvallend omdat de lengte van het contract alleen significant was voor de verkopers en niet voor de kopers. Mangoboeren bleken zich goed bewust van het feit dat hun markt wordt gedomineerd door korte-termijn contracten. Het vermijden van lange-termijn contracten gaf hen de mogelijkheid om flexibel te blijven voor veranderingen in vraag en aanbod die zij niet kunnen controleren. Producenten probeerden wel lange-termijn contracten te maken maar konden in het spel net zo goed herhaalde korte-termijn contracten maken met dezelfde handelspartner. Dit soort terugkerende contracten blijkt gebaseerd op vertrouwen en vriendschap en dus het netwerk-organisatiemechanisme. Als laatste bleek welvaart in de echte wereld een significante invloed te hebben op onderhandelingsmacht.
    Hoofdstuk 7 bespreekt de ervaringen met spelsimulatie als onderzoeksmethode en trekt conclusies uit de gecombineerde resultaten van de TTG en MCG. Sectie 7.1 bediscussieerd de ervaringen met spelsimulatie in het genereren en testen van hypotheses. Methodologisch zijn er verschillen tussen de TTG en MCG. De TTG vroeg veel meer tijd zowel voor de ontwerpcyclus als de empirische cyclus. De reden hiervoor is het gebruik van de hypothese genererende functie en het grotere aantal variabelen om te testen. De TTG startte met een brede blik op het probleem, waarbij de belangrijke variabelen van alle 4 de niveaus van het theoretisch raamwerk van Williamson (2000) nog gevonden moesten worden in de hypothese genererende fase. De MCG daarentegen gebruikte een analytisch model met minder, en op theorie gebaseerde variabelen. De sectie besteedt aandacht aan validiteit en betrouwbaarheid. Samenvattend blijkt dat de proces-validiteit het meest belangrijk was, en om het proces op gang te krijgen was psychologische realiteit noodzakelijk. De TTG en MCG zijn hierin beide geslaagd, maar via verschillende wegen. De MCG scoort ook positief op de structuur- en voorspellende validiteit door de nauwere benadering van de realiteit in hetgeen is gemodelleerd en het gebruik van echte mangoboeren in plaats van studenten. Speciale aandacht verdient de stelling over wat is gemodelleerd in de spelsimulatie.
    De multi-agent simulatie is ontwikkeld om gevoeligheidsanalyse te kunnen doen van configuraties van variabelen. Dit project is niet zover gekomen dat configuraties van variabelen direct uit de multi-agent simulatie konden worden getest in spelsessies. Nader onderzoek moet duidelijk maken of een multi-agent simulatie echt helpt om het aantal sessies dat nodig is om interessante configuraties te vinden te reduceren. Dit project heeft echter laten zien dat het mogelijk is om een multi-agent model te maken en te valideren van een spelsimulatie.
    De verschillende typen data die de TTG en MCG kunnen genereren zijn moeilijk te verkrijgen met andere methoden. Spelsimulatie is speciaal omdat de deelnemers worden blootgesteld aan een laboratorium-achtige situatie die hen isoleert van de echte (handels)wereld. Binnen dit laboratorium kan de aandacht van de deelnemers worden toegespitst op een specifiek probleem terwijl de volle rijkheid van menselijk gedrag wordt behouden. Gebaseerd op de ervaringen gepresenteerd in dit boek kan spelsimulatie worden gepositioneerd als een onderzoeksmethode die een hele range aan data verzamelingen kan faciliteren. Het is mogelijk om data te verzamelen voor, tijdens en na een sessie, met een combinatie van vragenlijsten, interviews en observaties van handelingen. Het kan verschillen tussen mensen in een sessie analyseren, of tussen sessies de effecten van varieren met de configuratie van variabelen en de situering of zelfs met de regels, rollen, doelen en beperkingen. De combinatie van kwantitatieve en kwalitatieve analyse die mogelijk zijn met spelsimulatie maken de methode een goede kandidaat voor onderzoek waarin beide gecombineerd moeten worden. De ontwerpcyclus van de MCG en TTG waren gebaseerd op kwalitatieve analyse terwijl de emprische cyclus van beide was gebaseerd op kwantitatief werk.
    Sectie 7.2 vergelijkt de theoretische conclusies van de TTG met die van de MCG en zoekt de relatie met de onderzoeksvraag. De conclusies van de MCG zijn in lijn met die van de TTG in zoverre dat de variabelen van sociale structuur zoals gebruikt in dit boek (vertrouwen, embeddedness en normen en waarden) duidelijk de mix van organisatiemechanismen beïnvloeden. Zowel de TTG als de MCG laten zien dat vertrouwen en embeddedness leiden tot het gebruik van het netwerk-organisatiemechanisme, maar ook tot lagere inkomsten binnen de omgeving van de spelsessies. Het lijkt erop dat het netwerk-organisatiemechanisme essentieel is in handelsnetwerken met onafhankelijke bedrijven, maar niet op een manier die rechtstreeks leid tot meer inkomsten. De conclusies van de twee spelsimulaties zijn in tegenspraak met de heersende opvatting in de literatuur over handelsnetwerken dat vertrouwen en relaties van belang zijn voor een succesvol bedrijf. De conclusies lijken meer op klassieke economische theorie, waarin bedrijven transacties zien als het rationele resultaat van prijs en product.
    Sectie 7.3 presenteert enkele ideeën voor nader onderzoek, onderverdeeld in ideeën voor het domein en voor methodologische verbeteringen. Sectie 7.4 bespreekt implicaties van dit onderzoek voor het domein van voedselhandelsketen en –netwerken. De toepassing van spelsimulatie als (een van de ) onderzoeksmethode(n) kan van waarde zijn door het verzamelen van data over echt gedrag van echte deelnemers in een gesimplificeerde ‘surrogaat’-omgeving, bepaald door de spelsimulatie. Dit boek laat zien dat er een laboratorium voor keten- en netwerkstudies is gebouwd. Sectie 7.5 geeft implicaties van dit onderzoek voor andere domeinen en beargumenteert dat de onderwerpen omtrent vertrouwen, embeddedness en andere variabelen van sociale structuur ook in de meeste andere (handels)domeinen aanwezig zijn, waarmee nieuwe mogelijkheden voor het gebruik van spelsimulatie kunnen worden gevonden.
    Hoofdstuk 7 eindigt met enkele concluderende opmerkingen in Sectie 7.6, waarin gezegd wordt dat dit book met een voorbeeld heeft laten zien dat spelsimulatie een goede methode is voor gecontroleerde analyse van complexe sociale systemen. Het heeft ook laten zien dat de de mogelijkheden van een herhaalbaar experiment in een gecontroleerde contextuele setting inzicht geeft in sociaal economisch gedrag op een manier die met verschillende theorieën benaderd kan worden. Binnen een theoretisch kader blijven kan de volledige rijkheid van menselijk gedrag niet verklaren, en dus zijn verbindingen tussen theorieën noodzakelijk. In dit boek is het theoretisch raamwerk van nieuwe institutionele economie gebruikt en zijn eerste pogingen gedaan voor verbindingen met cultuurtheorie, psychologie en andere theorieën uit de sociale wetenschappen. Toekomstig onderzoek zou spelsimulatie kunnen gebruiken als methode voor echt interdisciplinair onderzoek.

    Linking of repeated games: when does it lead to more cooperation and pareto improvements?
    Folmer, H. ; Mouche, P.H.M. van - \ 2007
    Milan - Italy : Fondazione Eni Enrico Mattei (Fondazione Eni Enrico Mattei Working Papers paper 19) - 15
    speltheorie - milieubeleid - wiskundige modellen - economie - econometrie - milieueconomie - game theory - environmental policy - mathematical models - economics - econometrics - environmental economics
    Game theory at work: OR models and algorythms to solve multi-actor heterogeneous decision problems
    Sáiz Pérez, M.E. - \ 2007
    Wageningen University. Promotor(en): Adrie Beulens; Jack van der Vorst, co-promotor(en): Eligius Hendrix. - [S.l.] : S.n. - ISBN 9789085047698 - 141
    speltheorie - modellen - algoritmen - optimalisatiemethoden - operationeel onderzoek - beslissingsmodellen - modelleren - game theory - models - algorithms - optimization methods - operations research - decision models - modeling
    Key words: Game theory, operations research, optimisation methods, algorithms. The objective of this thesis is to explore the potential of combining Game Theory (GT) models with Operations Research (OR) modelling. This includes development of algorithms to solve these complex OR models for different empirical situations. The challenge is to get GT “at work” by applying such models and techniques to practical cases. Four different cases with a challenge on the development of algorithms are studied. A first case illustrates a multiple coalition formation game in which membership rules and different transfer schemes are described. Given the GT model and the OR model, the goal is to develop methods for checking stability of coalition structures. A new mathematical programming formulation, crucial for the development of the algorithms, is elaborated. Available data is used to determine which stable coalitions appear and which procedures (transfer schemes) can be used to make coalitions stable. Also the influence of membership rules (whether actors are free to become a member) is investigated. Main conclusion is that transfer schemes are useful to be implemented to obtain stable coalitions. Moreover, different membership rules, e.g. veto or majority voting of current members, generate different results with and without transfer schemes. A second case studies a model of coalition formation in politics with n parties trying to form a government. Given the number of parties n and policy dimension m (number of items), computational algorithms are developed to compute all possible majority coalitions and preferences of parties over those coalitions. Application to Dutch data and theoretical examples leads to testing of hypotheses with surprising results with respect to coalition formation such as: being a first mover is not necessarily advantageous, being less flexible is not necessarily advantageous, forming a minimal winning coalition is not necessarily advantageous. A third case describes a two-stage location-quantity game where n > 2 firms are competing on m > 2 markets. The space where the firms can locate are nodes on a network. Analytical solutions for the supplying decisions and properties for determining the number of suppliers to each market are derived. In finding the equilibria, a complete enumeration algorithm and a local search algorithm are used. Two cases are elaborated to illustrate the procedures and the analytical results. The last case deals with a competitive facility location problem in which the concept of Stackelberg leader-follower problem is applied. The follower problem and leader problem are global optimisation problems. Branch-and-Bound (B&B) algorithms that guarantee to find the optimum of both problems are designed.
    Dynamic Transfer Schemes and Stability of International Climate Coalitions
    Nagashima, M.N. ; Dellink, R.B. ; Ierland, E.C. van - \ 2006
    Wageningen : Mansholt Graduate School (Working paper / Mansholt Graduate School : Discussion paper ) - 25
    speltheorie - emissie - klimaatverandering - klimaat - internationale verdragen - opwarming van de aarde - optimalisatiemethoden - milieueconomie - economische modellen - game theory - emission - climatic change - climate - international agreements - global warming - optimization methods - environmental economics - economic models
    This paper examines the formation and stability of coalitions in international climate agreements with a combined game-theoretic and integrated assessment model. The empirical model comprises twelve regions and investigates partial coalition formation in a one-shot cartel game. We argue that a dynamic transfer scheme, based on a full path of emissions over the planning horizon, can overcome some of the major obstacles in international negotiations by incorporating the expected growth of emissions in developing countries in the distribution of emission permits. The simulation results show that permit trading based on grandfathering permits proportionate to a static base year level of emissions may lead to counter-intuitive transfer flows, and no stable coalitions emerge. This is resolved under a dynamic transfer scheme: we then find two small stable coalitions: a coalition between the European Union (EU15) and China, or a coalition between Japan and India.
    The netchain laboratory
    Meijer, S.A. ; Hofstede, G.J. ; Beers, G. ; Omta, S.W.F. - \ 2004
    In: Dynamic in Food Chains: Proceedings of the 6th International Conference on Chain and Network Management in Agribusiness and the Food Industry, Ede, Netherlands, 27-28 May 2004. - Wageningen : Wageningen Pers - p. 203 - 210.
    simulatiemodellen - speltheorie - efficiëntie - voedselproductie - simulation models - game theory - efficiency - food production
    Spelsimulaties met melkveehouders en akkerbouwers in november 2003 rond varianten van gebruiksnormen: studie in kader van Evaluatie Meststoffenwet 2004
    Beldman, A.C.G. ; Daatselaar, C.H.G. ; Doornewaard, G.J. ; Janssens, S.R.M. ; Prins, H. - \ 2004
    Den Haag : LEI (Rapport / LEI : Domein 3, Natuurlijke hulpbronnen en milieu ) - ISBN 9789052429045 - 76
    landbouwbeleid - speltheorie - spellen - melkveehouderij - akkerbouw - normen - regelingen - mineralen - voedingsstoffenbalans - dierlijke meststoffen - agrarische bedrijfsvoering - nederland - agricultural policy - game theory - games - dairy farming - arable farming - standards - regulations - minerals - nutrient balance - animal manures - farm management - netherlands
    In opdracht van de Minister van LNV is, ten behoeve van de 'Evaluatie Meststoffenwet 2004', een deelproject ten aanzien van het nieuwe Gebruiksnormenstelsel uitgevoerd. In oktober 2003 heeft het Europese Hof aangegeven dat Nederland moet overgaan tot een Gebruiksnormenstelsel, daar men het Minas-systeem niet aan vindt sluiten bij de EU-Nitraatrichtlijn. In november 2004 zijn met groepen melkveehouders en akkerbouwers spelsimulaties uitgevoerd om inzicht te krijgen in effecten van dit nieuwe normenstelsel.
    Games for interactive spatial planning: SPLASH a prototype strategy game about water management
    Wachowicz, M. ; Vullings, L.A.E. ; Broek, M. van den; Ligtenberg, A. - \ 2003
    Wageningen : Alterra (Alterra-rapport 667) - 55
    waterbeheer - ruimtelijke ordening - simulatie - computerspelen - ontwerp - speltheorie - water management - physical planning - simulation - computer games - design - game theory
    The research project Games for interactive spatial planning was carried out within the programme Virtual countryside. This programme aims at exploring new methodologies and technologies to deal with the increasing complexity of the countryside, An overview of games in general, characteristics and genres of games, differences between computerized and non-computerized games, research items and game design procedures are discussed. The interactive planning process and the role games can play in it are described. Finally a case description of the improvement of the prototype SPLASH is given.
    Over de ratio van coöperatie : een speltheoretische benadering met een toepassing bij de mogelijke invloed van diergeneesmiddelen op voedselveiligheid = About reasons for cooperation : a game theoretical approach and an application to the potential influence of veterinary medicinal products on food safety
    Vaarkamp, H. - \ 2001
    Wageningen University. Promotor(en): G. van Dijk; A. Pijpers. - S.l. : S.n. - ISBN 9789058083791 - 136
    samenwerking - boeren - dierenartsen - speltheorie - computersimulatie - antibioticumresiduen - voedselveiligheid - voedingsmiddelenwetgeving - veterinaire producten - besluitvorming - cooperation - farmers - veterinarians - game theory - computer simulation - antibiotic residues - food safety - food legislation - veterinary products - decision making

    The central question in this study is: how can cooperation emerge in a non policed society? Due to the increasing availability of computers the answer has been sought by game theorists, too. In earlier times the search for the answer was characterised by trying to find simple patterns in a complex reality, but game theorists try to compose complex reality by evolutionary development starting with simple virtual individuals interacting according simple rules. Cooperation and its counterpart defection are studied by using the Prisoner's Dilemma (PD). In the 1980s the strategy TIT FOR TAT (TFT) has been discovered to use the right amount of cooperation to generate stable development. The essential elements of TFT are: always a cooperative start, immediate retaliation when confronted with defection and immediate reconciliation. The discovery of TFT has been inspirational to many scientists; the strategy has been analysed thoroughly and improvements have been proposed. Sociobiologists have found examples of the application of TFT in real life many times.

    In this study we pay attention to the history of TFT, the Prisoner's Dilemma and the game theoretical analysis.

    For cooperation to emerge direct reciprocity has been a conditio sine qua non , so counterparts had to meet over and over again. In 1998 the results of an experiment showed that indirect reciprocity could do the job as well. The experiment used a complex computer simulation model which was rebuilt by us. Surprisingly enough, the repetition of the experiment gave different results all the time, which questioned the conclusion. A hundredfold repetition showed the published result to be just one of many potential outcomes. We then have modified the model by introducing trust. A new series of one hundred experiments showed the original conclusion now to be right: indirect reciprocity is sufficient to make cooperation emerge, but trust is needed. This might be the first time that trust is no longer restricted to the field of belief, hope and love, and has become part of the rational answer to the central question. Fukuyama already established the importance of trust in (economical) life, but he considered trust to be part of the economically important phenomena which cannot be explained rationally.

    Next, the modified computer simulation model has been applied to an every day practical situation where a veterinary surgeon and a farmer must decide about medication of food producing animals. First the importance of veterinary medicinal products (VMPs) and especially antimicrobial agents is shown, not only as beneficial compounds for animal health and animal welfare but as risks as well, being potential sources of residues in food originating from animals. Part of the study is some work about residues caused by a widely used VMP for piglets containing penicillin. The aim of this work is to prove the correctness of legislation concerning residues. Farmers and veterinarians are prone to doubt this correctness. But MRLs do really matter. A survey of the results of an enquiry among 30 European veterinary surgeons regarding this subject is given; this survey shows the issue to exist among veterinarians.

    Using the modified model the problem to study was to find out how to guarantee that both farmer and veterinarian take the right decisions concerning food safety. Cooperation is respecting the waiting time and defection is not respecting it. The results of the application of the modified model are proof that payoff for the farmer is the most important factor. Educational ability of the veterinary surgeon does have some influence, too, but this influence is only moderate.

    Whereas the first part of the study increases our knowledge about cooperative science the second part illustrates a rather new approach to veterinary questions.

    Onderhandelingsstrategie en rentevoet.
    Noort, P.C. van den - \ 1989
    De Landeigenaar 35 (1989)2. - ISSN 0166-5839 - p. 3 - 5.
    economie - speltheorie - rentetarieven - rente - internationale economie - internationale betrekkingen - wereldeconomie - economics - game theory - interest rates - interest - international economy - international relations - world economy
    De voordelen van een bepaalde onderhandelingswijze van regeringen kunnen pas na een tijd beoordeeld worden. De totale eindscore wordt dan ook door intern en extern rendement bepaald
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