Votes and Lobbying in the European Decision-Making Process: Application to the European Regulation on GMO Release

The paper presents a multi-agent model simulating a two-level public decision game in which politicians, voters and interest groups interact. The objective is to model the political market for influence at the domestic level and at the international level, and to assess how new consultation procedures affect the final decision. It is based on public choice theory as well as on political science findings. We consider in this paper that lobbying groups have different strategies for influencing voters and decision-makers, with long-term and short-term effects. Our computational model enables us to represent the situation as an iterative process, in which past decisions have an impact on the preferences and choices of agents in the following period. In the paper, the model is applied to the European decision-making procedure for authorizing the placing on the market of Genetically Modified Organisms (GMO). It illustrates the political links between public opinions, lobbying groups and elected representatives at the national scale in the 15 country members, and at the European scale. It compares the procedure which was defined by the European 1990/220 Directive in 1990 with the new procedure, the 2001/18 Directive, which replaced it in 2001. The objective is to explore the impact of the new decision rules and the reinforced public participation procedures planned by the 2001/18 Directive on the lobbying efficiency of NGOs and biotechnology firms, and on the overall acceptability of the European decision concerning the release of new GMOs on the European territory.Lobbying, Europe, GMO, Multi-Agent Simulation, Public Choice, Politician, Voter, Group Contest

An organization that transmits opinion to newcomers

We aim to identify the conditions under which social influence enables emergence of a shared opinion orientation among members of an organization over time, when membership is subject to continuous but partial turnover. We study an intra-organizational advice network that channels social influence over time, with a flow of joiners and leavers at regular intervals. We have been particularly inspired by a study of the Commercial Court of Paris, a judicial institution whose members are peer-elected businesspeople and are partly replaced every year. We develop an agent-based simulation of advice network evolution which incorporates a model of opinion dynamics based on a refinement of Deuant's relative agreement", combining opinion with a measure of "uncertainty" or openness to social influence. We focus on the effects on opinion of three factors, namely criteria for advisor selection, duration of membership in the organization, and new members' uncertainty. We show that criteria for interlocutor choice matter: a shared opinion is sustained over time if members select colleagues at least as experienced as themselves. Convergence of opinions appears in other congurations too, but the impact of initial opinion fades in time. Duration has an impact to the extent that the longer the time spent in the group, the stronger the possibility for convergence towards a common opinion. Finally, higher uncertainty reinforces convergence while lower uncertainty leads to coexistence of multiple opinions.social influence, advice networks, intra-organizational networks, opinion dynamics, agent-based simulation

When overconfident agents slow down collective learning

This paper presents a model of influence where agents' beliefs are based on an objective reality, such as the properties of an environment. The perception of the objective reality is not direct: all agents know is that the more correct a belief, the more successful the actions that are deduced from this belief. (A pair of agents can influence each other when )Agents can influence eachother by pair when they perform a joint action. They are not only defined by individual beliefs, but also idyosynchratic confidence in their belief - this means that they are not all willing to (engage in action with) act with agents with a different belief and to be influenced by them. We show here that the distribution of confidence in the group has a huge impact on the speed and quality of collective learning and in particular that a small number of overconfident agents can prevent the whole group frow learning properly.agent-based computational economics;belief dissemination;bounded-confidence;simulation agents;social influence

CAN OPINION BE STABLE IN AN OPEN NETWORK WITH HIERARCHY?AN AGENT-BASED MODEL OF THE COMMERCIAL COURT OF PARIS

The co-evolution of social networks and opinion formation has received increasing attention in recent years. As a contribution to the growing literature on this topic, we explore connections between empirical data representing the advice network of judges at the Commercial Court in Paris and an agent-based simulation protocol testing various hypotheses on the motives that drive agent behaviors. A previous work (Rouchier et al. 2007) had already modeled the dynamics of advice-seeking among judges and studied the implications of different rationality assumptions on the shape of the emerging network. Here, we add an influence model to the previously examined advice-seeking relationships in order to explore the possibility that there is a form of “culture” at the Court that harmonizes the opinions of members over time; we identify a set of relevant stylized facts, and we use new indicators to evaluate how agents choose with whom to interact within this framework. The basic assumptions we analyze are that they seek advice from senior judges who are higher up in the hierarchy, who enjoy high reputation, or who are similar to them. Our simulations test which criterion –or which combination of criteria– is most credible, by comparing both the properties of the emerging network and the dynamics of opinion at the Court to the stylized facts. Our results single out the combination of criteria that most likely guide individuals' selection of advisors and provide insight into their effects on opinion formation.Advice network ; Agent-Based Simulation ; Influence Model ; Opinion Dynamics ; Hierarchy ; Reputation

The influence of seller learning and time constraints on sequential bargaining in an artificial perishable goods market

This paper investigates the formation of prices in a perishable goods market where agents bargain repeatedly through pair-wise interactions. After extensive field observations, we chose to focus on two aspects that seem important to actors of this market : the passage of time and update in judgement when gathering information. The main feature of the market is that a seller bargaining with a buyer has incomplete information about buyer's willingness to pay and is not sure how her trading partner will evaluate an offer or compare it with other options. On the other hand, buyers have limited time to look for good sand cannot meet all possible sellers before making a decision. Hence agents cannot calculate the best price to offer but receive information through limited interactions, and use this information to choose their actions. An agent-based model was built to represent a frame work that mimics the observed market institution and where agent's possible behaviours and learning was made as consistent as possible with gathered data. Simulations were run, first for sensitivity analysis concerning main parameters, then to test the dependence of agents'learning to (a) the time buyers can spend on the market and (b) the frequency of update in learning by sellers. To validate the model, features produced by the simulated market are compared to the stylized facts gathered for negotiation about four goods. We reproduce the main features of the data on the dynamics of offers, transaction prices and agents'behavior during the bargaining phases.Cet article porte sur la formation des prix dans un marché de biens périssables où les agents négocient de gré à gré de façon répétée. Après avoir accompli un important travail sur le terrain, nous choisissons de nous concentrer sur deux aspects importants pour les acteurs : le temps et les changements de jugements des individus qui reçoivent de nouvelles informations. Ce marché se caractérise par une méconnaissance par le vendeur des critères de choix de son client (valeur de réservation, comment ce client évalue les offres reçues et les compare aux autres options sur le marché). D'autre part, les acheteurs ont une contrainte temporelle et ne peuvent pas rencontrer tous les vendeurs avant de prendre une décision. Ainsi, acheteurs et vendeurs ne peuvent pas calculer le meilleur prix à offrir ou à accepter mais, recevant des informations au cours de leurs rencontres, ils adaptent leur comportement à cette information. Nous avons construit un modèle multi-agents dont l'environnement reproduit un marché empirique (le MIN, marché de gros en fruits et légumes de Marseille) et dont les agents ont des règles de décision et d'apprentissage cohérentes avec les données de terrain. Des simulations ont permis de tester l'impact marginal de chaque paramètre puis de deux variables précises : (a) le temps que les acheteurs passent sur le marché et (b) la fréquence de réévaluation de ses croyances par le vendeur. Pour valider le modèle, nous comparons les faits produits par le marché simulé et ceux provenant de données empiriques réelles concernant les négociations et transactions pour 4 types de biens. Nous reproduisons les faits principaux concernant la dynamique des offres, les prix des transactions et l'émergence de négociation

Evolving Informal Risk-Sharing Cooperatives and Other-Regarding Preferences

In this paper we present a model of formation and destruction of informal cooperatives in a population of agents who perform a risky activity and who are heterogeneous in terms of success in their actions. Although some agents have high-risk and others low-risk, our model displays a dynamics with cooperatives in which agents share equally their income with a certain stability. We are interested in studying at the same time the existence of cooperatives, their ability to integrate a large proportion of agents and the degree of segregation of these cooperatives. Three factors can explain the existence, stability and lack of segregation. First, we show that the classical explanation in economics holds within the framework of our model: when agents are risk averse, high success agents can share with low success agents so that to stabilize the value of their income - the higher the risk aversion, the more stable the cooperatives and the lower the segregation. Learning can explain in a small proportion the existence of cooperatives: we designed agents so that they have to learn whether they are high or low-risk, and while they are learning, they tend to create cooperatives that can last. Eventually we worked on the integration of other-regarding preferences in the model, with two different definitions. As expected, the influence of other-regarding preferences is to increase stability and decrease segregation, and the two models of rationality react differently to the type of network in which the agents are immersed. This paper, mainly exploratory, presents our model and shows the influence of the definition of network as well as all other factors presented before. In that sense, although we have mainly done a rough exploration of its relevant parameters for the moment, it exposes different insights that can be gained by its study

CAN OPINION BE STABLE IN AN OPEN NETWORK WITH HIERARCHY?<br />AN AGENT-BASED MODEL OF THE COMMERCIAL COURT OF PARIS

The co-evolution of social networks and opinion formation has received increasing attention in recent years. As a contribution to the growing literature on this topic, we explore connections between empirical data representing the advice network of judges at the Commercial Court in Paris and an agent-based simulation protocol testing various hypotheses on the motives that drive agent behaviors. A previous work (Rouchier et al. 2007) had already modeled the dynamics of advice-seeking among judges and studied the implications of different rationality assumptions on the shape of the emerging network. Here, we add an influence model to the previously examined advice-seeking relationships in order to explore the possibility that there is a form of “culture” at the Court that harmonizes the opinions of members over time; we identify a set of relevant stylized facts, and we use new indicators to evaluate how agents choose with whom to interact within this framework. The basic assumptions we analyze are that they seek advice from senior judges who are higher up in the hierarchy, who enjoy high reputation, or who are similar to them. Our simulations test which criterion –or which combination of criteria– is most credible, by comparing both the properties of the emerging network and the dynamics of opinion at the Court to the stylized facts. Our results single out the combination of criteria that most likely guide individuals' selection of advisors and provide insight into their effects on opinion formation

D'une charte l'autre. Le processus de révision de la charte des AMAP comme indicateur d'une institution qui se renforce ?

Les AMAP ont connu une croissance assez linéaire et même assez forte, puisqu'après leur apparition en 2001, elles étaient déjà de l'ordre de 500 en 2006, et environ 1600 en 2013. Très tôt, dès 2001, le réseau s'est structuré sous la forme d'associations régionales dans certaines régions. Si la question de la structuration nationale des AMAP s'est posée très tôt, ce n'est qu'en 2009 qu'une partie de ces réseaux régionaux se fédèrent dans une structure nationale, MIRAMAP. En 2003, Alliance Provence a déposé à l'Inpi le nom AMAP dont l'utilisation était dés lors subordonnée au respect de la " charte des AMAP" (datant elle aussi de 2003)1. Cette charte était, comme l'indique son texte, " un document de référence définissant les valeurs, les principes et les engagements auxquels doivent souscrire les associations désirant être reconnues comme AMAP auprès d'Alliance Provence ", elle n'est en rien un règlement intérieur aux AMAP, chaque AMAP devant " définir de façon autonome son mode de fonctionnement dans le respect de la présente charte ". Cette charte a été révisée en 2013, suite à une grande consultation nationale orchestrée par MIRAMAP. Nous montrons dans cet article l'évolution de la charte, les règles qui ont disparu ou au contraire sont apparues pour fixer de nouveaux objectifs, tout en répondant à la réalité des pratiques que les acteurs ont développé dans les dix dernières années. En outre, le cadre d'analyse IAD d'Elinor Ostrom, permet de montrer en quoi l'institution s'est renforcée grâce à la mise en place de cette révision participative

Un dispositif de coordination pour une gouvernance alimentaire CAHIER DU LAMSADE, février 2016, N° 371

La région Provence-Alpes-Côte-d'Azur (PACA) a décidé d'initier, suite à desrencontres qui ont débuté en 2010, un observatoire régional des circuits courts. Son butaffiché est de coordonner les acteurs et de mutualiser les moyens des différents circuits courtsdéjà existants dans la région dans la perspective du développement de nouvelles initiatives.Cet article présente une évaluation préliminaire de l'« Observatoire régional des circuitscourts » décrit comme un dispositif institutionnel, en considérant son objectif affiché d’initierun processus de gouvernance. L'analyse de la participation à l'observatoire et de ce qui a étéproduit dans son cadre (références, données, modes d'organisation) a été mené de 2010 à2014. Cette étude identifie ainsi l’activation d'une proximité organisée et permet de définirl'observatoire comme un dispositif de coordination des acteurs opérationnel. Le processus degouvernance initié demeure néanmoins fragil

L'Observatoire Régional des Circuits Courts : Un Dispositif de Coordination pour une Gouvernance Alimentaire Régionale

The region of Provence-Alpes-Côte d'Azur (PACA) has decided to initiate, following discussions that began in 2010, a regional observatory of short food chains. Its aim is to coordinate actors and optimize the resources of existing short food chains in the region, in perspective of the development of new initiatives. This article presents a preliminary assessment of the "Regional Observatory short circuits", described as an institutional arrangement, with regards to its goal of encouraging governance. The analysis was conducted from 2010 to 2014. It targets references, data and organizational devices issued from the work sessions as well as meeting attendance and planning. The results illustrate the emergence of an organized proximity and define the Observatory as an operational coordination device. However, the governance processes initiated remain fragile.La région Provence-Alpes-Côte-d'Azur (PACA) a décidé d'initier, suite à des rencontres qui ont débuté en 2010, un observatoire régional des circuits courts. Son but affiché est de coordonner les acteurs et de mutualiser les moyens des différents circuits courts déjà existants dans la région dans la perspective du développement de nouvelles initiatives. Cet article présente une évaluation préliminaire de l'« Observatoire régional des circuits courts » décrit comme un dispositif institutionnel, en considérant son objectif affiché d’initier un processus de gouvernance. L'analyse de la participation à l'observatoire et de ce qui a été produit dans son cadre (références, données, modes d'organisation) a été mené de 2010 à 2014. Cette étude identifie ainsi l’activation d'une proximité organisée et permet de définir l'observatoire comme un dispositif de coordination des acteurs opérationnel. Le processus de gouvernance initié demeure néanmoins fragile