Clinical Associate Professor of Epidemiology
Dr. Erez Hatna works in the fields of geoinformatics, spatial analysis, agent-based modeling, and studies urban dynamics, residential segregation, scaling laws of urban systems, and infectious disease modeling.
Dr. Hatna studies ethnic and economic residential patterns of cities using agent-based computational models of relocating households. The models simulate the formation of residential patterns as an outcome of relocation decisions of households. Dr. Hatna also studies the statistical regularities of urban systems and urban scaling. His research focuses on how the choice of urban boundaries influences the scaling relationships.
At NYU, Dr. Hatna is part of the Agent-based Modeling Lab, which works with large-scale epidemic models and cognitively plausible agents in order to produce a transformative synthesis for global public health modeling. Previously, he has conducted research at Wageningen University, University College London, and Johns Hopkins University.
PhD, Geography, Tel Aviv University, Tel Aviv, IsraelMA, Geography, Tel Aviv University, Tel Aviv, Israel
Agent-Based ModelingEpidemiologyGeographic Information Science (GIS)Geospatial MethodsInfectious DiseasesMathematical and Computational ModelingModeling Social and Behavioral DynamicsUrban Informatics
Coresidency of Immigrant Groups in a Diverse Inner-City Neighborhood of Whitechapel, LondonFlint-Ashery, S., & Hatna, E. (n.d.).
Journal titleHousing Policy Debate
Page(s)487-502AbstractA single family occupying one residential unit is the typical residential arrangement in cities of the Global North. However, specific communities tend to practice coresidency, wherein several families share the same residential unit. In this study, we evaluate immigrant groups’ coresidency tendencies in London’s East End Whitechapel neighborhood, through a door-to-door survey and interviews. We differentiate between horizontal and vertical family structures and find that a sizable percentage (44.4%) of the residential units were shared by two or more families. At the neighborhood level, we show that the segregated residential pattern of groups was correlated with the pattern of coresidency, indicating that the uneven spatial concentration of ethnic groups led to high densities of families in specific parts of Whitechapel. The interviews reveal that coresidency is not merely a result of economic constraints but also a residential preference reflecting the need for cohabitation with extended family members.
Generating Mixed Patterns of Residential Segregation: An Evolutionary ApproachGunaratne, C., Hatna, E., Epstein, J. M., & Garibay, I. (n.d.).
Issue2AbstractThe Schelling model of residential segregation has demonstrated that even the slightest preference for neighbors of the same race can be amplified into community-wide segregation. However, these models are unable to simulate mixed, coexisting patterns of segregation and integration, which have been seen to exist in cities. Using evolutionary model discovery we demonstrate how including social factors beyond racial bias when modeling relocation behavior enables the emergence of strongly mixed patterns. Our results indicate that the emergence of mixed patterns is better explained by multiple factors influencing the decision to relocate; the most important being the interaction of nonlinear, rapidly diminishing racial bias with a recent, historical tendency to move. Additionally, preference for less isolated neighborhoods or preference for neighborhoods with longer residing neighbors may produce weaker mixed patterns. This work highlights the importance of exploring the influence of multiple hypothesized factors of decision making, and their interactions, within agent rules, when studying emergent outcomes generated by agent-based models of complex social systems.
Special Section on "Inverse Generative Social Science": Guest Editors’ StatementEpstein, J. M., Garibay, I., Hatna, E., Koehler, M., & Rand, W. (n.d.).
Issue2AbstractThis is a guest editors’ statement accompanying the publication of a special issue on "Inverse Generative Social Science", published in volume 26, issue 2, 2023 of JASSS-Journal of Artificial Societies and Social Simulation".
Privacy and contact tracing efficacyBenthall, S., Hatna, E., Epstein, J. M., & Strandburg, K. J. (n.d.).
Journal titleJournal of the Royal Society Interface
Issue194AbstractAs the COVID-19 pandemic emerged, public health authorities and software designers considered the possibility that smartphones could be used for contact tracing to control disease spread. Smartphone-based contact tracing was attractive in part because it promised to allow the tracing of contacts that might not be reported using traditional contact tracing methods. Comprehensive contact tracing raises distinctive privacy concerns, however, that have not been previously explored. Contacts outside of an individual's ordinary social network are more likely to be privacy-sensitive, making fear that such contacts will be disclosed a potential disincentive to adoption of smartphone contact tracing. Here, we modify the standard SEIR infectious disease transmission model to incorporate contact tracing and perform a series of simulations aimed at studying the importance of tracing socially distant (and potentially privacy-sensitive) contacts. We find that, for a simple model network, ensuring that distant contacts are traced is surprisingly unimportant as long as contact tracing adoption is sufficiently high. These results suggest that policy-makers designing contact tracing systems should be willing to trade off comprehensiveness for more widespread adoption.
Triple contagion: A two-fears epidemic modelEpstein, J. M., Hatna, E., & Crodelle, J. (n.d.).
Journal titleJournal of the Royal Society Interface
Issue181AbstractWe present a differential equations model in which contagious disease transmission is affected by contagious fear of the disease and contagious fear of the control, in this case vaccine. The three contagions are coupled. The two fears evolve and interact in ways that shape distancing behaviour, vaccine uptake, and their relaxation. These behavioural dynamics in turn can amplify or suppress disease transmission, which feeds back to affect behaviour. The model reveals several coupled contagion mechanisms for multiple epidemic waves. Methodologically, the paper advances infectious disease modelling by including human behavioural adaptation, drawing on the neuroscience of fear learning, extinction and transmission.
Evidence for localization and urbanization economies in urban scalingSarkar, S., Arcaute, E., Hatna, E., Alizadeh, T., Searle, G., & Batty, M. (n.d.).
Journal titleRoyal Society Open Science
Issue3AbstractWe study the scaling of (i) numbers of workers and aggregate incomes by occupational categories against city size, and (ii) total incomes against numbers of workers in different occupations, across the functional metropolitan areas of Australia and the USA. The number of workers and aggregate incomes in specific high-income knowledge economy-related occupations and industries show increasing returns to scale by city size, showing that localization economies within particular industries account for superlinear effects. However, when total urban area incomes and/or gross domestic products are regressed using a generalized Cobb-Douglas function against the number of workers in different occupations as labour inputs, constant returns to scale in productivity against city size are observed. This implies that the urbanization economies at the whole city level show linear scaling or constant returns to scale. Furthermore, industrial and occupational organizations, not population size, largely explain the observed productivity variable. The results show that some very specific industries and occupations contribute to the observed overall superlinearity. The findings suggest that it is not just size but also that it is the diversity of specific intra-city organization of economic and social activity and physical infrastructure that should be used to understand urban scaling behaviours.
Defining urban clusters to detect agglomeration economiesCottineau, C., Finance, O., Hatna, E., Arcaute, E., & Batty, M. (n.d.).
Journal titleEnvironment and Planning B: Urban Analytics and City Science
Page(s)1611-1626AbstractAgglomeration economies are a persistent subject of debate in regional science and city planning. Their definition turns on whether or not larger cities are more efficient than smaller ones. Here, we complement existing discussions on agglomeration economies by providing a sensitivity analysis of estimated externalities to the definitions of urban agglomeration. We regress wages versus population and jobs over thousands of different definitions of cities in France, based on an algorithmic aggregation of spatial units. We also search for evidence of larger inequalities in larger cities. This paper therefore focuses on the spatial and economic complexity of the mechanisms defining agglomeration within and between cities.
Diverse cities or the systematic paradox of Urban Scaling LawsCottineau, C., Hatna, E., Arcaute, E., & Batty, M. (n.d.).
Journal titleComputers, Environment and Urban Systems
Page(s)80-94AbstractScaling laws are powerful summaries of the variations of urban attributes with city size. However, the validity of their universal meaning for cities is hampered by the observation that different scaling regimes can be encountered for the same territory, time and attribute, depending on the criteria used to delineate cities. The aim of this paper is to present new insights concerning this variation, coupled with a sensitivity analysis of urban scaling in France, for several socio-economic and infrastructural attributes from data collected exhaustively at the local level. The sensitivity analysis considers different aggregations of local units for which data are given by the Population Census. We produce a large variety of definitions of cities (approximatively 5000) by aggregating local Census units corresponding to the systematic combination of three definitional criteria: density, commuting flows and population cutoffs. We then measure the magnitude of scaling estimations and their sensitivity to city definitions for several urban indicators, showing for example that simple population cutoffs impact dramatically on the results obtained for a given system and attribute. Variations are interpreted with respect to the meaning of the attributes (socio-economic descriptors as well as infrastructure) and the urban definitions used (understood as the combination of the three criteria). Because of the Modifiable Areal Unit Problem (MAUP) and of the heterogeneous morphologies and social landscapes in the cities' internal space, scaling estimations are subject to large variations, distorting many of the conclusions on which generative models are based. We conclude that examining scaling variations might be an opportunity to understand better the inner composition of cities with regard to their size, i.e. to link the scales of the city-system with the system of cities.
Cities and regions in Britain through hierarchical percolationArcaute, E., Molinero, C., Hatna, E., Murcio, R., Vargas-Ruiz, C., Masucci, A. P., & Batty, M. (n.d.).
Journal titleRoyal Society Open Science
Issue4AbstractUrban systems present hierarchical structures at many different scales. These are observed as administrative regional delimitations which are the outcome of complex geographical, political and historical processes which leave almost indelible footprints on infrastructure such as the street network. In this work, we uncover a set of hierarchies in Britain at different scales using percolation theory on the street network and on its intersections which are the primary points of interaction and urban agglomeration. At the larger scales, the observed hierarchical structures can be interpreted as regional fractures of Britain, observed in various forms, from natural boundaries, such as National Parks, to regional divisions based on social class and wealth such as the well-known North– South divide. At smaller scales, cities are generated through recursive percolations on each of the emerging regional clusters. We examine the evolution of the morphology of the system as a whole, by measuring the fractal dimension of the clusters at each distance threshold in the percolation. We observe that this reaches a maximum plateau at a specific distance. The clusters defined at this distance threshold are in excellent correspondence with the boundaries of cities recovered from satellite images, and from previous methods using population density.
Defining urban agglomerations to detect agglomeration economiesCottineau, C., Finance, O., Hatna, E., Arcaute, E., & Batty, M. (n.d.).
Journal titlearXivAbstractAgglomeration economies are a persistent subject of debate among economists and urban planners. Their definition turns on whether or not larger cities and regions are more efficient and more productive than smaller ones. We complement existing discussion on agglomeration economies and the urban wage premium here by providing a sensitivity analysis of estimated coefficients to different delineations of urban agglomeration as well as to different definitions of the economic measure that summarises the urban premium. This quantity can consist of total wages measured at the place of work, or of income registered at the place of residence. The chosen option influences the scaling behaviour of city size as well as the spatial distribution of the phenomenon at the city level. Spatial discrepancies between the distribution of jobs and the distribution of households at different economic levels makes city definitions crucial to the estimation of economic relations which vary with city size. We argue this point by regressing measures of income and wage over about five thousands different definitions of cities in France, based on our algorithmic aggregation of administrative spatial units at regular cutoffs which reflect density, population thresholds and commuting flows. We also go beyond aggregated observations of wages and income by searching for evidence of larger inequalities and economic segregation in the largest cities. This paper therefore considers the spatial and economic complexity of cities with respect to discussion about how we measure agglomeration economies. It provides a basis for reflection on alternative ways to model the processes which lead to observed variations, and this can provide insights for more comprehensive regional planning.
Regions and cities in Britain through hierarchical percolationHatna, E., & Al., . (n.d.).
Combining segregation and integration: Schelling model dynamics for heterogeneous populationHatna, E., & Benenson, I. (n.d.).
Issue4AbstractThe Schelling model is a simple agent-based model that demonstrates how individuals’ relocation decisions can generate residential segregation in cities. Agents belong to one of two groups and occupy cells of rectangular space. Agents react to the fraction of agents of their own group within the neighborhood around their cell. Agents stay put when this fraction is above a given tolerance threshold but seek a new location if the fraction is below the threshold. The model is well-known for its tipping point behavior: an initially random (integrated) pattern remains integrated when the tolerance threshold is below 1/3 but becomes segregated when the tolerance threshold is above 1/3. In this paper, we demonstrate that the variety of the Schelling model’s steady patterns is richer than the segregation–integration dichotomy and contains patterns that consist of segregated patches of each of the two groups, alongside areas where both groups are spatially integrated. We obtain such patterns by considering a general version of the model in which the mechanisms of the agents' interactions remain the same, but the tolerance threshold varies between the agents of both groups. We show that the model produces patterns of mixed integration and segregation when the tolerance threshold of an essential fraction of agents is either low, below 1/5, or high, above 2/3. The emerging mixed patterns are relatively insensitive to the model’s other parameters.
Constructing cities, deconstructing scaling lawsArcaute, E., Hatna, E., Ferguson, P., Youn, H., Johansson, A., & Batty, M. (n.d.).
Journal titleJournal of the Royal Society Interface
Issue102AbstractCities can be characterized and modelled through different urban measures. Consistency within these observables is crucial in order to advance towards a science of cities. Bettencourt et al. have proposed that many of these urban measures can be predicted through universal scaling laws. We develop a framework to consistently define cities, using commuting to work and population density thresholds, and construct thousands of realizations of systems of cities with different boundaries for England and Wales. These serve as a laboratory for the scaling analysis of a large set of urban indicators. The analysis shows that population size alone does not provide us enough information to describe or predict the state of a city as previously proposed, indicating that the expected scaling laws are not corroborated. We found that most urban indicators scale linearly with city size, regardless of the definition of the urban boundaries. However, when nonlinear correlations are present, the exponent fluctuates considerably.
On the problem of boundaries and scaling for urban street networksMasucci, A. P., Arcaute, E., Hatna, E., Stanilov, K., & Batty, M. (n.d.).
Journal titleJournal of the Royal Society Interface
Issue111AbstractUrban morphology has presented significant intellectual challenges to mathematicians and physicists ever since the eighteenth century, when Euler first explored the famous Königsberg bridges problem. Many important regularities and scaling laws have been observed in urban studies, including Zipf's law and Gibrat's law, rendering cities attractive systems for analysis within statistical physics. Nevertheless, a broad consensus on how cities and their boundaries are defined is still lacking. Applying an elementary clustering technique to the street intersection space, we show that growth curves for the maximum cluster size of the largest cities in the UK and in California collapse to a single curve, namely the logistic. Subsequently, by introducing the concept of the condensation threshold, we show that natural boundaries of cities can be well defined in a universal way. This allows us to study and discuss systematically some of the regularities that are present in cities. We show that some scaling laws present consistent behaviour in space and time, thus suggesting the presence of common principles at the basis of the evolution of urban systems.
Paradoxical Interpretations of Urban Scaling LawsCottineau, C., Hatna, E., Arcaute, E., & Batty, M. (n.d.).
Journal titlearXivAbstractScaling laws are powerful summaries of the variations of urban attributes with city size. However, the validity of their universal meaning for cities is hampered by the observation that different scaling regimes can be encountered for the same territory, time and attribute, depending on the criteria used to delineate cities. The aim of this paper is to present new insights concerning this variation, coupled with a sensitivity analysis of urban scaling in France, for several socio-economic and infrastructural attributes from data collected exhaustively at the local level. The sensitivity analysis considers different aggregations of local units for which data are given by the Population Census. We produce a large variety of definitions of cities (approximatively 5000) by aggregating local Census units corresponding to the systematic combination of three definitional criteria: density, commuting flows and population cutoffs. We then measure the magnitude of scaling estimations and their sensitivity to city definitions for several urban indicators, showing for example that simple population cutoffs impact dramatically on the results obtained for a given system and attribute. Variations are interpreted with respect to the meaning of the attributes (socio-economic descriptors as well as infrastructure) and the urban definitions used (understood as the combination of the three criteria). Because of the Modifiable Areal Unit Problem and of the heterogeneous morphologies and social landscapes in the cities internal space, scaling estimations are subject to large variations, distorting many of the conclusions on which generative models are based. We conclude that examining scaling variations might be an opportunity to understand better the inner composition of cities with regard to their size, i.e. to link the scales of the city-system with the system of cities.
Combining segregation and integration: Schelling model dynamics for heterogeneous populationHatna, E., & Benenson, I. (n.d.).
Journal titlearXivAbstractThe Schelling model is a simple agent based model that demonstrates how individuals' relocation decisions generate residential segregation in cities. Agents belong to one of two groups and occupy cells of rectangular space. Agents react to the fraction of agents of their own group within the neighborhood around their cell. Agents stay put when this fraction is above a given tolerance threshold but seek a new location if the fraction is below the threshold. The model is well known for its tipping point behavior: an initial random (integrated) pattern remains integrated when the tolerance threshold is below 1/3 but becomes segregated when the tolerance threshold is above 1/3. In this paper, we demonstrate that the variety of the Schelling model steady patterns is richer than the segregation-integration dichotomy and contains patterns that consist of segregated patches for each of the two groups alongside patches where both groups are spatially integrated. We obtain such patterns by considering a general version of the model in which the mechanisms of agents' interactions remain the same but the tolerance threshold varies between agents of both groups. We show that the model produces patterns of mixed integration and segregation when the tolerance threshold of most agents is either below the tipping point or above 2/3. In these cases, the mixed patterns are relatively insensitive to the model's parameters.
Influence of provider and urgent care density across different socioeconomic strata on outpatient antibiotic prescribing in the USAKlein, E. Y., Makowsky, M., Orlando, M., Hatna, E., Braykov, N. P., & Laxminarayan, R. (n.d.).
Journal titleJournal of Antimicrobial Chemotherapy
Page(s)1580-1587AbstractObjectives: Despite a strong link between antibiotic use and resistance, and highly variable antibiotic consumption rates across the USA, drivers of differences in consumption rates are not fully understood. The objective of this study was to examine how provider density affects antibiotic prescribing rates across socioeconomic groups in the USA. Methods: We aggregated data on all outpatient antibiotic prescriptions filled in retail pharmacies in the USA in 2000 and 2010 from IMS Health into 3436 geographically distinct hospital service areas and combined this with socioeconomic and structural factors that affect antibiotic prescribing from the US Census. We then used fixedeffect models to estimate the interaction between poverty and the number of physician offices per capita (i.e. physician density) and the presence of urgent care and retail clinics on antibiotic prescribing rates. Results:We found large geographical variation in prescribing, driven in part by the number of physician offices per capita. For an increase of one standard deviation in the number of physician offices per capita there was a 25.9% increase in prescriptions per capita. However, the determinants of the prescription ratewere dependent on socioeconomic conditions. In poorer areas, clinics substitute for traditional physician offices, reducing the impact of physician density. In wealthier areas, clinics increase the effect of physician density on the prescribing rate. Conclusions: In areas with higher poverty rates, access to providers drives the prescribing rate. However, in wealthier areas, where access is less of a problem, a higher density of providers and clinics increases the prescribing rate, potentially due to competition.
Assessing spatial uncertainties of land allocation using a scenario approach and sensitivity analysis: A study for land use in EuropeVerburg, P. H., Tabeau, A., & Hatna, E. (n.d.).
Journal titleJournal of Environmental Management
Page(s)S132-S144AbstractLand change model outcomes are vulnerable to multiple types of uncertainty, including uncertainty in input data, structural uncertainties in the model and uncertainties in model parameters. In coupled model systems the uncertainties propagate between the models. This paper assesses uncertainty of changes in future spatial allocation of agricultural land in Europe as they arise from a general equilibrium model coupled to a spatial land use allocation model. Two contrasting scenarios are used to capture some of the uncertainty in the development of typical combinations of economic, demographic and policy variables. The scenario storylines include different measurable assumptions concerning scenario specific drivers (variables) and parameters. Many of these assumptions are estimations and thus include a certain level of uncertainty regarding their true values. This leads to uncertainty within the scenario outcomes. In this study we have explored how uncertainty in national-level assumptions within the contrasting scenario assumptions translates into uncertainty in the location of changes in agricultural land use in Europe. The results indicate that uncertainty in coarse-scale assumptions does not translate into a homogeneous spread of the uncertainty within Europe. Some regions are more certain than others in facing specific land change trajectories irrespective of the uncertainty in the macro-level assumptions. The spatial spread of certain and more uncertain locations of land change is dependent on location conditions as well as on the overall scenario conditions. Translating macro-level uncertainties to uncertainties in spatial patterns of land change makes it possible to better understand and visualize the land change consequences of uncertainties in model input variables.
City boundaries and the universality of scaling lawsHatna, E., & Al., . (n.d.).
Long-term changes in the configuration of agriculture and natural areas around cities in the Netherlands (1900-1990)Hatna, E., & Bakker, M. M. (n.d.). In Modeling of Land-use and Ecological Dynamics.
Page(s)37-49AbstractCities' influence on the spatial configuration of land in their proximity has presumably changed during the last century as agriculture, cities, and transportation evolved. Investigation of these changes has been limited due to the limited availability of historical maps in digital form. In this chapter, we employ a set of digitized historical land-cover maps in order to compare the spatial distribution of cropland, pasture, and nature surrounding cities in the Netherlands for three time periods: 1900, 1960 and 1990. Our findings suggest that the land cover around cities was relatively stable during these time periods. However, we discovered that, near the perimeter of cities, in 1900, we could discern a clear trend of higher fractions of cropland. These tendencies weakened by the middle of the century and almost completely ceased by 1990.
The schelling model of ethnic residential dynamics: Beyond the integrated - segregated dichotomy of patternsHatna, E., & Benenson, I. (n.d.).
Issue1AbstractThe Schelling model of segregation is an agent-based model that illustrates how individual tendencies regarding neighbors can lead to segregation. The model is especially useful for the study of residential segregation of ethnic groups where agents represent householders who relocate in the city. In the model, each agent belongs to one of two groups and aims to reside within a neighborhood where the fraction of 'friends' is sufficiently high: above a predefined tolerance threshold value F. It is known that depending on F, for groups of equal size, Schelling's residential pattern converges to either complete integration (a random-like pattern) or segregation. The study of high-resolution ethnic residential patterns of Israeli cities reveals that reality is more complicated than this simple integration-segregation dichotomy: Some neighborhoods are ethnically homogeneous while others are populated by both groups in varying ratios. In this study, we explore whether the Schelling model can reproduce such patterns. We investigate the model's dynamics in terms of dependence on group-specific tolerance thresholds and on the ratio of the size of the two groups. We reveal new type of model pattern in which a portion of one group segregates while another portion remains integrated with the second group. We compare the characteristics of these new patterns to the pattern of real cities and discuss the differences.
Abandonment and Expansion of Arable Land in EuropeHatna, E., & Bakker, M. M. (n.d.).
Page(s)720-731AbstractAbandonment of arable land is often assumed to happen mostly in marginal areas where the conditions for arable cultivation are relatively unfavorable, whereas arable expansion is expected to occur mostly in areas with favorable conditions. This assumption, used in many land-use change forecasts, was never properly tested, mainly because the relatively short period of full-coverage land-use inventories did not allow a systematic analysis of the phenomena. With the recent release of CORINE 2006 this has changed. In this article, we explore the typical locations of abandonment and expansion of arable land in Europe during the period 1990-2006 by means of logistic regressions. More specifically, we test whether or not locations of abandonment and expansion can be inferred from the location characteristics of arable land in 1990. If the above assumption holds, this should be the case. We demonstrate that although arable expansion indeed happens in locations that resemble the bulk of arable land in 1990 (the presumably favorable locations), arable abandonment does not necessarily happen in locations that resemble the bulk of uncultivated land (that is, the presumably unfavorable locations). In other words, the assumption does not hold. Particularly, areas close to the road network were found to be associated with both high abandonment rates and high expansion rates, which suggest that abandonment is not limited to areas that are marginal in terms of agricultural production.
Changing environmental characteristics of European croplandBakker, M. M., Hatna, E., Kuhlman, T., & Mücher, C. A. (n.d.).
Journal titleAgricultural Systems
Page(s)522-532AbstractThe spatial configuration of agricultural systems is continuously changing in response to changes in demand for agricultural goods, changes in the level of competition between different land use activities, and progress in agricultural technology. This may lead to a change in the location of agricultural systems and consequently to a change in their average environmental characteristics. This paper explores the change in environmental characteristics of cropland (horticulture and field crops) over the years 1950, 1990 and 2000, for Western and Eastern Europe, using basic descriptive statistics. Underlying mechanisms are explored with logistic (interaction) regression analysis.We find that in both Eastern and Western Europe, crop cultivation shifted away from cities. In Western Europe cropland became situated on shallower soils, steeper slopes, and drier and less accessible areas. Probable reasons are that technical progress reduced the importance of traditional constraints such as drought, poor soils, and distance from markets, so that crop farmers were allowed to move to warm and sunny areas where potential productivity is highest. In addition, cropland probably lost some of its competitive power to grassland and nature. In Eastern Europe cropland concentrated on deeper soils and flatter terrain from 1990 onward. Here, the abandonment of the central planning system and a more flexible land market must have allowed a shift of cropland towards more suitable locations.
Geosimulation of income-based Urban residential patternsHatna, E., & Benenson, I. (n.d.). In Advanced Geo-Simulation Models.
Page(s)111-125AbstractMaps of high-resolution residential patterns of Israeli cities reveal essential spatial heterogeneity in relation to family income, a situation that was found in eight of the nine cities investigated. Modern urban theory provides several explanations of how homogeneous urban patterns self-organize and persist; however the mechanisms that allow the persistence of heterogeneous patterns remain unexplained. We argue that the observed residential heterogeneity can be explained on the basis of householders' residential preferences and behavior. Namely, the householders differ in respect to their willingness to reside near poorer neighbors. Residential heterogeneity is the consequence of this variability. In order to investigate this hypothesis, we developed an agent-based model of residential dynamics in the city, which extends the Schelling model of segregation. Model residential agents represent families, which differ in their economic abilities and their tolerance of poorer neighbors. Using the model, we demonstrate that quite a low fraction of tolerant agents is sufficient for the emergence and persistence of heterogeneous residential areas in the city. This result is robust to the uncertainty of our knowledge about the fraction of highly tolerant agents - the variation in this fraction only weakly influences the resulting urban heterogeneity. We thus conclude that the presence of residential agents who are tolerant of their poorer neighbors is sufficient to explain long-term urban heterogeneity and we discuss the possible consequences of this result for the theory of urban gentrification.
Minority-majority relations in the schelling model of residential dynamicsBenenson, I., & Hatna, E. (n.d.).
Journal titleGeographical Analysis
Page(s)287-305AbstractThe Schelling model describing segregation between two groups of residential agents, reflects the most abstract, basic view of noneconomic forces motivating residential migrations: be close to people of "your ownkind. The model assumes that residential agents, located in neighborhoods where the fraction of "friendsis less than a predefined threshold value F, try to relocate to neighborhoods where this fraction is F or higher. For groups of equal size, Schelling's residential pattern converges either to complete integration (random pattern) or segregation, depending on F. We investigate Schelling model pattern dynamics as a function of F in addition to two other parameters-the ratio of groups' numbers, and neighborhood size. We demonstrate that the traditional integration-segregation pattern dichotomy should be extended. In the case of groups of different sizes, a wide interval of F-values exists that entails a third persistent residential pattern, one in which a portion of the majority population segregates while the rest remains integrated with the minority. We also demonstrate that Schelling model dynamics essentially depend on the formalization of urban agents' residential behavior. To obtain realistic results, the agents should be satisficers, and the fraction of the agents relocating irrespective of the neighborhood's state should be nonzero. We discuss the relationship between our results and real-world residential dynamics. Relaciones entre minoría y mayoría en el modelo de dinámica residencial de Schelling El modelo de Schelling describe la segregación entre dos grupos de agentes residenciales (Schelling 1971, 1978) a partir del supuesto más básico y abstracto acerca de las fuerzas no económicas que motivan las migraciones residenciales: la cercanía a gente de "su mismotipo. El modelo asume que los agentes residenciales, ubicados en los barrios donde la fracción de "amigoses menor a un valor umbral predefinido F, tratarán de trasladarse a los vecindarios donde esta fracción es F o mayor. Para grupos de igual tamaño, el patrón residencial de Schelling converge ya sea hacia la integración completa (modelo aleatorio), o hacia la segregación, en función al valor de F. Los autores investigan las dinámicas del patrón modelo de Shelling en función a F y a dos parámetros adicionales: el ratio o tasa de tamaño de los grupos, y el tamaño del barrio/vecindad. Los resultados demuestran que la dicotomía tradicional de patrones de integración-segregación debe ser revisada y ampliada. En el caso de grupos de diferentes tamaños, se halló que existe un amplio intervalo de valores para F, lo cual supone un tercer tipo de patrón residencial persistente: un patrón en el que una parte (o grupo) mayoritario de la población se segrega, mientras que el resto de esta mayoría permanece integrado con la minoría. También se demuestra que las dinámicas del modelo de Schelling dependen esencialmente de la formalización del comportamiento residencial de los agentes urbanos. Para obtener resultados realistas, los agentes deben ser satisfactores (satisficers), y la fracción de los agentes que se reubican debe ser distinta a cero, independientemente de las características de 4 vecindad. Finalmente, los autores discuten la relación entre sus resultados y las dinámicas residenciales en el mundo real.