Spatial Interaction Models

The recent decade has witnessed a new wave of development in the place-based accessibility theory, revolving around the two-step floating catchment area (2SFCA) method. The 2SFCA method, initially serving to evaluate the spatial inequity of health care services, has been further applied to other urban planning and facility access issues. Among these applications, different distance decay functions have been incorporated in the thread of model development, but their applicability and limitations have not been thoroughly examined. To this end, the paper has employed a place-based accessibility framework to compare the performance of twenty-four 2SFCA models in a comprehensive manner. Two important conclusions are drawn from this analysis: on a small analysis scale (e.g., community level), the catchment size is the most critical model component; on a large analysis scale (e.g., statewide), the distance decay function is of elevated importance. In sum, this comparative analysis provides the theoretical support necessary to the choice of the catchment size and the distance decay function in the 2SFCA method. Justification of model parameters through empirical evidence (e.g., field surveys about local travel activities) and model validation through sensitivity analysis are needed in future 2SFCA applications for various urban planning, service delivery, and spatial equity scenarios.

With the continuous development of science and technology, the intelligent development of community system becomes a trend. Meanwhile, smart mobile devices and cloud computing technology are increasingly used in intelligent information systems; however, smart mobile devices such as smartphone and smart pad, also known as thin clients, limited by either their capacities (CPU, memory or battery) or their network resources, do not always meet users' satisfaction in using mobile services. Mobile cloud computing, in which resource-rich virtual machines of smart mobile device are provided to a customer as a service, can be terrific solution for expanding the limitation of real smart mobile device, but the resources utilization rate is low and the information cannot be shared easily. To address the problems above, this paper proposes an information system for intelligent community, which is composed of thin clients, wide band network and cloud computing servers. On one hand, the thin clients with the characteristics of energy efficiency, high robustness and high computing capacity can efficiently avoid the problems encountered in the PC architecture and mobile devices. On the other hand, the cloud computing servers in the proposed information system solve the problems of resource sharing barriers. Finally, the system is built in real environments to evaluate the performance. We deploy the proposed system in a community with more than 2000 residents, and it is demonstrated that the proposed system is robust and efficient.

El Cristo Mojado es una réplica del Señor de Esquipulas llevada a Los Ángeles de manera ilegal por parte de los migrantes devotos de origen centroamericano en el año 2003, motivo por el cual es venerado por miles de personas que se identifican con él. En su desplazamiento a la Iglesia de Santa Cecilia, recinto que lo cobija al oriente de dicha ciudad, las personas generan relaciones espaciales en diferentes niveles escalares que, con el transcurrir del tiempo, han moldeado la forma en que se organiza el espacio circundante, que diferencia la dinámica de otras que sucede en lugares que poseen réplicas del Cristo Negro en esa zona de Estados Unidos. Por lo anterior, el trabajo a presentar tiene como objetivo principal explicar los procesos de interacción espacial desencadenados por la devoción a esta imagen. Para ello, se expondrán los elementos teórico-conceptuales e históricos que contextualizan la devoción, así como las estrategias metodológicas y resultados obtenidos en el trabajo de campo, que incluyó, entre otras cosas, observación participante en la fiesta patronal, así como entrevistas casuales y a profundidad con visitantes, comerciantes, líderes espirituales y con las personas que llevaron la imagen e impulsaron la devoción.

n this article, a Gaussian-based two-step floating catchment area (2SFCA) model is applied to evaluate the geographical
accessibility to Supplemental Nutrition Assistance Program (SNAP)-authorized retailers. First, the proposed method con-
siders the interaction between the food supply (in terms of categorized benefit redemptions) and demand (in terms of
benefit-receiving households). Second, the model is used to visualize food access patterns at the level of refined administra-
tive units (i.e., census block groups). The developed food access metric was compared to the U.S. Department of
Agriculture (USDA) Food Access Research Atlas, justifying the validity of this new method for small area estimation. The
following are important observations: (1) the choice of catchment size had a considerable impact on the accessibility
measure in urban areas (or when small statistical units are used); (2) the 2SFCA measurement had a higher level of corres-
pondence with that of the USDA Atlas at a smaller catchment size for identifying low food access units; and (3) there was
no significant inequality regarding SNAP accessibility with respect to different socioeconomic deprivation variables. This
new method can better assist the SNAP administration with store authorization on a refined geographic scale.

Nonlinear estimation of the gravity model with Poisson/negative binomial methods has become popular to model international trade flows, because it permits a better accounting for zero flows and extreme values in the distribution tail. Nevertheless, as trade flows are not independent from each other due to spatial autocorrelation, these methods may lead to biased parameter estimates. To overcome this problem, eigenvector spatial filtering variants of the Poisson/negative binomial specification have been proposed in the literature of gravity
modelling of trade. However, no specific treatment has been developed for cases in which many zero flows are present. This paper contributes to the literature in two ways. First, by employing a stepwise selection criterion for spatial filters that is based on robust (sandwich) p-values and does not require likelihood-based indicators. In this respect, we develop an ad hoc backward stepwise function in R. Second, using this function, we select a reduced set of spatial filters that properly accounts for importer-side and exporter-side specific spatial effects, both at the count and the logit processes of zero-inflated methods. Applying this
estimation strategy to a cross-section of bilateral trade flows between a set of worldwide countries for the year 2000, we find that our specification outperforms the benchmark models in terms of model fitting, both considering the AIC and in predicting zero (and small) flows.

China has built a territory-based formal e-waste recycling system as a response to the global e-waste challenge. This system created a division of labor between the informal sector and formal recycling plants by providing a subsidy to the latter to buy waste products collected by the former. Using provincial data of formal e-waste recycling plants in China in 2014, this paper quantifies the contribution of the informal sector to e-waste transportation at the national level. Despite the intention to plan a regional self-sufficient system for e-waste recycling at the provincial level, we find that significant interprovincial flows exist due to the complex market transactions within the informal collection network, which reveals the deep conflicts between market mechanism and public intervention in the evolvement of e-waste governance structure. We built a spatial interaction model to depict the interregional flows of e-waste that can quantitatively illustrate the change of spatial pattern of this network due to the introduction of the formal WEEE regulation in China. In conclusion, we discuss the policy implications for optimizing regional allocation of the e-waste recycling capacity as well as for improving the transparency of the reverse logistic system to include the informal sector in the future.

Open access : https://www.frontiersin.org/articles/10.3389/fdigh.2016.00010/full

Filet, Clara. 2017. « An Attempt to Estimate the Impact of the Spread of Economic Flows on Latenian Urbanization ». Frontiers in Digital Humaninites (3:10). doi: 10.3389/fdigh.2016.00010.


Over a relatively short period between the end of the fourth and the middle of the first century BC, an unprecedented process of urbanization developed in non-Mediterranean Europe. Among all the factors contributing to the rise of the first agglomerations possessing urban characteristics in this area, this article focuses on the role of commercial interactions. The ability of settlements to interact within the trade network is approached by modeling of interactions. The aim is to provide new material to estimate the extent to which this factor could have impacted the known hierarchy of settlements on the one hand, and its role in the development of the Latenian urbanization process on the other hand.

Nonlinear estimation of the gravity model with Poisson-type regression methods has become popular for modelling international trade flows, because it permits a better accounting for zero flows and extreme values in the distribution tail. Nevertheless, as trade flows are not independent from each other due to spatial and network autocorrelation, these methods may lead to biased parameter estimates. To overcome this problem, eigenvector spatial filtering (ESF) variants of the Poisson/negative binomial specifications have been proposed in the literature on gravity modelling of trade. However, no specific treatment has been developed for cases in which many zero flows are present. This paper contributes to the literature in two ways. First, by employing a stepwise selection criterion for spatial filters that is based on robust (sandwich) p-values and does not require likelihood-based indicators. In this respect, we develop an ad hoc backward stepwise function in R. Second, using this function, we select a reduced set of spatial filters that properly accounts for importer-side and exporter-side specific spatial effects, as well as network effects, both at the count and the logit processes of zero-inflated methods. Applying this estimation strategy to a cross-section of bilateral trade flows between a set of 64 countries for the year 2000, we find that our specification outperforms the benchmark models in terms of model fitting, both considering the AIC and in predicting zero (and small) flows

El análisis de las externalidades en el sector inmobiliario ha atraído desde hace varios años la atención de los investigadores suscitando una gran cantidad de estudios al respecto. En este artículo se utilizan modelos econométricos tradicionales, de la econometría espacial y de regresión ponderada geográficamente, para analizar y comparar a la luz de estos modelos la influencia que tiene en los precios de las viviendas la existencia de una estación del metro en San Javier ubicada en el centro occidente de la ciudad de Medellín. El principal hallazgo en este estudio es que la presencia de la estación del metro tiene una influencia positiva en los precios de las viviendas localizadas en un radio de 600 metros alrededor de la estación; sin embargo, las viviendas cercanas a las vías de acceso del metro a la estación presentan un importante decremento en sus precios.

The main purpose of lctools is to assist researchers and educators to use user friendly tools for calculating key spatial statistics. These include: Local Pearson and Geographically Weighted Pearson Coefficients, Spatial Inequality Measures (Gini, Spatial Gini, LQ, Focal LQ), Spatial Autocorrelation (Global and Local Moran's I) and other Spatial Analysis tools (Geographically Weighted Statistics, Inferential Statistics). This package also contains functions for statistical inference for each statistic calculated.

Carleton University Master of Computer Science Degree Thesis
Topic:  An Evaluation of Two Dimensional and Three Dimensional User Interfaces for Colour Selection
Field of Study:  Three dimensional user interfaces for use with spatial interaction devices

The present effort is made for studying the essential of GIS based surveillance tool for dengue epidemic control in India. The dengue epidemic cases and the mortality caused by dengue has becomes essentially public health important in India, and the situation has become worst since, 2006. Dengue cases were clinically confirmed with thousands of cases and hundreds of deaths annually. India has highest record of 37070 dengue cases and 227 deaths across the country during 2012. The report of dengue epidemics is becomes daily news now days and it was reported from 24 states and Union Territories in India during 2012. The dengue epidemics were reported across the country during the period of April to November annually, however, the vulnerability of epidemics was reported between the periods of mid July to mid November of every year, since 2006. The environmental and climate variables are fuelling to creating conducing environment for profusion of dengue vector mosquitoes Aedes species ( Ae. aegypti or Ae. Albopictus ). The information relevant to the geographical site specification of dengue vectors breeding habitats, vector abundance, vector density, etc., could be recorded using global positioning systems (GPS). This information could be mapped and overlay on the thematic layers of climate variables (Temperature, relative humidity, saturation deficiency and Rainfall) under the geographical information systems (GIS) software platform for spatial analysis (cluster analysis, nearest neighbourhood analysis, fussy analysis, probability of maximum and minimum likelihood analysis etc.,) for prediction of disease epidemics 7 days in advance. The Google based internet GIS may perhaps, used to mapping real time situation and updating the information with online data base connectivity (ODBC) in the GIS engine for providing the real time information relevant to the dengue epidemics, and hence, the appropriate precaution measures will be taken to control dengue epidemics in the country early in advance.

Abstract: The development of local forms of spatial analysis has been the subject of intense research over last decade. In this paper we propose a local calibration procedure for handling varying parameter estimates of an origin-constrained spatial interaction model. In this context, the estimates of local parameters depends both on origins and destinations and a four dimensional space is involved. A suitable estimation of local parameters can be obtained by the maximisation of a weighted maximum likelihood function, exploiting the same principle of geographical weighted regression (GWR) approach.

In this paper a contribution is presented with respect to accessibility indicators modelling for commuters moving through the municipalities of Sardinia, in Italy. In this case, spatial complex network analysis is integrated into the construction of accessibility measures: one of the most relevant outcomes of the first tool –the detection of shortest road paths and distances- is adopted as an input for the second in modelling accessibility indicators. Instead of Euclidean distances
often adopted in the literature, shortest road distances are chosen, as commuting implies movements that are usually repeated daily and very likely subjected, even unconsciously, to
space and time minimization strategies.
In particular, two commuter accessibility indicators are constructed according to approaches based on a travel cost and a spatial interaction model with impedance function calibrated in
exponential and in power form. The accessibility indicators are confronted each other and with relevant socio-economic and infrastructure characteristics of Sardinia.
In addition, they are described, with respect to their spatial distribution and their different implications, when adopted in decision-making and planning. The travel cost based accessibility indicator has a municipal spatial distribution strongly influenced by the main road infrastructure of the Island. By contrast, spatial interaction model based accessibility indicators are more reliable, with respect to their capacity to confirm a leading socio-economic role of the municipalities comprehended in the metropolitan area of the capital town Cagliari.

The main aim of this article is to combine recent developments in spatial interaction modeling to better model and explain spatial decisions. The empirical study refers to migration decisions made by internal migrants from Athens, Greece. To achieve this, geographically weighted versions of standard and zero inflated Poisson (ZIP) spatial interaction models are defined and fit. In the absence of empirical studies for the effect of potential determinants on internal migration decisions in Greece and the presence of an excessive number of zero migration flows among municipalities in Greece, this article provides empirical evidence for the power of the proposed Geographically Weighted ZIP regression method to better explain destination choices of Athenian internal migrants. We also discuss statistical inference issues in relation to the application of the proposed regression techniques.