Spatial interactions in agent-based modeling

Agent Based Modeling (ABM) has become a widespread approach to model complex interactions. In this chapter after briefly summarizing some features of ABM the different approaches in modeling spatial interactions are discussed. It is stressed that agents can interact either indirectly through a shared environment and/or directly with each other. In such an approach, higher-order variables such as commodity prices, population dynamics or even institutions, are not exogenously specified but instead are seen as the results of interactions. It is highlighted in the chapter that the understanding of patterns emerging from such spatial interaction between agents is a key problem as much as their description through analytical or simulation means. The chapter reviews different approaches for modeling agents' behavior, taking into account either explicit spatial (lattice based) structures or networks. Some emphasis is placed on recent ABM as applied to the description of the dynamics of the geographical distribution of economic activities, - out of equilibrium. The Eurace@Unibi Model, an agent-based macroeconomic model with spatial structure, is used to illustrate the potential of such an approach for spatial policy analysis.Comment: 26 pages, 5 figures, 105 references; a chapter prepared for the book "Complexity and Geographical Economics - Topics and Tools", P. Commendatore, S.S. Kayam and I. Kubin, Eds. (Springer, in press, 2014

Privacy as a Public Good

Privacy is commonly studied as a private good: my personal data is mine to protect and control, and yours is yours. This conception of privacy misses an important component of the policy problem. An individual who is careless with data exposes not only extensive information about herself, but about others as well. The negative externalities imposed on nonconsenting outsiders by such carelessness can be productively studied in terms of welfare economics. If all relevant individuals maximize private benefit, and expect all other relevant individuals to do the same, neoclassical economic theory predicts that society will achieve a suboptimal level of privacy. This prediction holds even if all individuals cherish privacy with the same intensity. As the theoretical literature would have it, the struggle for privacy is destined to become a tragedy. But according to the experimental public-goods literature, there is hope. Like in real life, people in experiments cooperate in groups at rates well above those predicted by neoclassical theory. Groups can be aided in their struggle to produce public goods by institutions, such as communication, framing, or sanction. With these institutions, communities can manage public goods without heavy-handed government intervention. Legal scholarship has not fully engaged this problem in these terms. In this Article, we explain why privacy has aspects of a public good, and we draw lessons from both the theoretical and the empirical literature on public goods to inform the policy discourse on privacy

Giving and Volunteering in the Netherlands : Sociological and Psychological Perspectives

Dissertation of the University of Utrecht Volunteer work, membership of voluntary associations, philanthropy and donation of blood and organs are studied by scholars from a wide range of disciplines. Sociologists and economists assume that good intentions are universal, but that some people have a stock of human and social capital that allows them to fulfill these intentions while others lack the resources to do so. Thus, they have studied the effects of financial capital (income and wealth), human capital (level of education and health), and social capital (community and religious involvement) on giving and volunteering. Personality and social psychologists, on the other hand, argue that across a variety of social conditions, some people are more likely to contribute because they have an ‘altruistic personality’: they are more helpful, empathic, or more able to take the perspective of people in need, while others are more likely to refuse, evade, or forget their duties. However, we know very little about the relative effects of personality characteristics and social conditions on prosocial behavior. Therefore, the first research question of this dissertation is: To what extent can giving and volunteering behavior be explained by prosocial motives and other psychological characteristics of people and the social conditions in which they live? But we know even less about the interactive effects of personality characteristics and social conditions. This is the second research question: In which conditions are prosocial motives and other psychological characteristics more strongly related to giving and volunteering? An economist would say: especially if it does not cost them too much. This idea is called the ‘low cost hypothesis’. Another idea in this regard originated in personality psychology, and predicts that people act upon their individual preferences when the expectations of others about their behavior are rather unclear. This idea is called the ‘weak situation hypothesis’. Using data of the Family Survey of the Dutch Population 2000 (n=1,587), I find that on average, about 30% of all the variance in the examples of prosocial behavior that was explained by the most extensive regression models was due to personality characteristics and social value orientations. The most distinctive characteristic of people who give time, money, blood and organs is their higher than average level of education. In addition, people who are more religious, live in smaller communities, work more hours for pay and earn higher incomes also tend to contribute more. In contrast to the low cost-hypothesis and the weak situation-hypothesis, personality is not more important for giving and volunteering when the price of giving is low or social pressure is weak. However, I found evidence that the relations of giving and volunteering with social conditions such as education or church attendance are partly due to personality characteristics; and that purely sociological studies of participation can lead to biased estimates of the effects of social conditions such as age and education. The major implication for scholars is that studies from either sociology or psychology are incomplete because they disregard the role of the determinants that are part of the other discipline. ___________________________ Meer dan tachtig procent van de Nederlandse huishoudens geeft geld aan ‘goede doelen’. Ongeveer één derde van de Nederlanders is regelmatig actief als onbetaald vrijwilliger voor een vereniging. Eén op de zes Nederlanders heeft besloten zijn of haar organen voor transplantatie of de wetenschap ter beschikking te stellen na de dood. En ongeveer één op de twintig Nederlanders geeft minstens één keer per jaar bloed bij de bloedbank. Geefgedrag – het geven van geld aan goede doelen, het geven van bloed, van organen, en het geven van tijd door vrijwilligerswerk – heet ook wel prosociaal gedrag. Het gaat om bijdragen aan collectieve goederen: zij vragen een persoonlijk offer van de gever, waarvan de baten ten goede komen aan groepen burgers of de samenleving als geheel. Wie geeft er eigenlijk tijd, geld, bloed en organen? En waarom geven deze mensen überhaupt tijd, geld, bloed en organen ten bate van anderen, als dat ten koste van henzelf gaat? Dit proefschrift bestudeert deze vragen vanuit twee verschillende disciplines in de sociale wetenschappen: vanuit de sociologie, en vanuit de sociale en persoonlijkheidspsychologie.