Improving accessibility to rural health services: The maximal covering network improvement problem

Accessibility to health facilities is a critical factor in effective health treatment for people in rural areas of lesser-developed countries. In many areas accessibility is diminished by the lack of all-weather roads, making access subject to weather conditions. Location-allocation models have been used to prescribe optimal configurations of health facilities in order to maximize accessibility, but these models are based on the assumption that the underlying transport network is static and always available. Essentially, past work has ignored the potential impacts of improvements to the transport system in modeling access. In this paper we propose a model that treats the opposite side of the location/transport equation; that is, a model that treats existing facility locations as fixed and improves health service accessibility by upgrading links of the transport network to all-weather roads. This new model, called the Maximal Covering Network Improvement Problem (MC-NIP) is formulated as an integer-linear programming problem. An application of the MC-NIP model to the Suhum District of Ghana is presented, which shows that even a modest level of road improvement can lead to substantial increases in all-season access to health service.     

Locating farmers’ markets with an incorporation of spatio-temporal variation

The recent drive among consumers to purchase fresh, healthy and environmentally friendly food has brought about a renewed interest in farmers’ markets. However, ensuring the success of a farmers’ market is not an easy task. Unlike general grocery stores, farmers’ markets often have very limited hours of service and are distributed sparsely in space. Both spatial and temporal constraints that people experience in their daily lives limit their accessibility to a farmers’ market. This research incorporates such constraints in the service provision planning of farmers’ markets. In particular, two models are proposed to select locations and the associated service schedules for a fixed number of farmers’ markets. A case study is conducted in Tucson, Arizona to demonstrate the merits of the new approach.     

Data center supply chain configuration design: A two-stage decision approach

Data centers are special-purpose facilities that enable customers to perform cloud based real-time online transactions and rigorous computing operations. Service levels of data center facilities are characterized by response time between query and action, which to a large extent depends on data center location and data travel distance. Another aspect of service level is resource up-time availability, which is determined by data center configuration. Data center location and configuration decisions are, therefore, of great significance to ensure uninterrupted operations in customers of manufacturing and service industries relying on cloud-based computing resources. In this study, following a grid-based location approach, we present two mixed integer linear programming models for capacitated single-source data center location-allocation problems. The first model provides optimal locations, capacities and configurations of data centers, and allocation of demands to open facilities when there is no existing facilities in the region. Our second model considers the decision problem of meeting new demand when the existing demand is met by the already opened facilities. We term these newly arrived demand as replication demand, which results either from emergence of new users of existing customers at distant locations in the future, or as a means of increasing data resilience by creating data replication as a backup. To solve the decision problem for meeting primary and replication demand optimally, we propose a two-stage decision algorithm. The algorithm provides optimal locations, capacities and configurations for new data centers, capacity addition decisions to the existing facilities and subsequent allocation of demands. Both models and solution algorithm are implemented using AMPL programming language and solved with CPLEX solver. The models are found to be scalable and capable to provide high quality solutions in reasonable time.     

The location of public services considering the mode of travel

By reason of their generally longer travel times, transit users are not so well-served by many public facilities as are automobile drivers. This paper investigates the implications of this fact for the location of a specific type of service, public child day care. A location-allocation model is employed to determine the most accessible locations for a set of centres in Edmonton, Canada, for users of both modes. Transit is found to be capable of providing only 51% of the accessibility of the automobile, at 2.4 times the average travel time. The argument is advanced that in order to reduce the inequality of service to a minimum, public facilities should be located with the accessibilities of transit users in mind. The optimal systems are compared with Edmonton's present system which is found to be spatially inefficient and quite discriminatory in its inefficiency against transit users. This is attributed to the city's piecemeal planning policy and an inadequate understanding of the notion of accessibility. The paper concludes by recommending improvements which would improve our simple diagnostic model to the level of a useful planning device.     

Location choice for direct foreign investment in new hospitals in China by using ANP and TOPSIS

This study models location choices for foreign direct investments in new hospitals in China as an multi-criteria decision-making (MCDM) problem and designs develops a multidirectional relationship decision model combines the techniques of analytic network process (ANP) and technique for order performance based on similarity to the ideal solution (TOPSIS). This study discusses applying ANP to the relative weighting of multiple assessment criteria. The TOPSIS approach is employed to rank 15 counties without the Zhoushan of China’s Yangtze River Delta (YRD) region in terms of their overall performance under the decision model. To illustrate how the proposed approach is applied to the problem of selecting locations for new hospitals in China an empirical study of a real case is performed. This study demonstrates the effectiveness and feasibility of the proposed assessment procedure.     

Network flow-based strategies for identifying rail park-and-ride facility locations

Many cities are considering introducing or expanding rail service in an effort to diversify their modal splits. Park-and-rides are integral to this strategy because they represent private auto users’ access points to the system. Proper placement of such facilities is a strategic location decision, as it can conceivably decrease vehicular traffic on congested roadways while benefiting users. This paper models the decision to locate park-and-ride facilities in a network flow-based framework. From this perspective, optimal placement occurs at locations where vehicles will encounter facilities early during their journeys to a centralized area or major activity center. Locating park-and-rides in this fashion maximizes the chances of removing users from the network. These elements are demonstrated in three hypothetical placement scenarios that make use of synthetic network and traffic flow data. Results illustrate the functionality of our approach for identifying park-and-ride candidate locations. Lastly, implications of our work are discussed in light of broader planning concerns and practical demands on rail facility location.     

On the equilibrium properties of locational sorting models

Important to many models of location choice is the role of local interactions or spillovers, whereby the payoffs from choosing a location depend in part on the number or attributes of other individuals or firms that choose the same or nearby locations in equilibrium. This paper develops the equilibrium properties of a broadly applicable and readily estimable class of sorting models that allow location decisions to depend on both fixed local attributes (including unobserved attributes) and local interactions, describes the conditions under which equilibria exist and are unique, and provides a test for uniqueness in empirical analyses of sorting equilibrium.     

The Determinants of Attendance at Neutral Site College Football Games

This paper develops a predictive model of attendance at neutral site Division 1‐A college football games. From 2004–2012 seasons, 427 games were identified and split into training and holdout data sets. A Tobit model is developed using matchup‐specific, game‐specific, location‐specific, and university‐specific determinants. Results are generally consistent with the existing literature on attendance modeling, showing that these prior home team‐specific models are adaptable to neutral site locations. Results are useful as they reveal how the selection of game location and matchup of opponents – decisions made by athletic directors or bowl officials – ultimately affect game‐day attendance. Copyright © 2014 John Wiley & Sons, Ltd.     

Analyzing the Relationships among Race,Wealth, and Home Ownership in America

This paper presents new evidence on the determinants of the large disparities in home ownership by race in the U.S. Consistent with results first reported by P. Linneman and S. M. Wachter (1989,AREOFA J.7, No. 4, 389–402), we find noceteris paribusracial differences in ownership rates among white and minority households who possess sufficient wealth to meet down payment and closing cost requirements associated with standard mortgage underwriting criteria. However, substantial racial differences among wealth-constrained households exist, with constrained whites owning at higher rates than observationally equivalent minority households. Because minorities are disproportionately constrained by wealth-related underwriting standards, these differentials apply to roughly one-third of the white households in our samples and well over one-half of the minority sample. A multinomial model that treats central city versus suburban location as a choice variable in addition to tenure status is also estimated. The results show that even among households unconstrained by wealth-related underwriting considerations, minorities are much more likely than whites to own in central city locations. Thus, while controlling for wealth constraint status does eliminate tenure choice differences among the unconstrained, location differences remain for this group. They also are present among constrained households. Given the disparate fortunes of central city and suburban land markets in many metropolitan areas, this racial location pattern of ownership may have important long-run impacts on wealth distribution by race.     

The flow-refueling location problem for alternative-fuel vehicles

Beginning with Hodgson (Geogr.Anal.22(1990) 270), several researchers have been developing a new kind of location-allocation model for “flow capturing.” Instead of locating central facilities to serve demand at fixed points in space, their models aim to serve demand consisting of origin-destination flows along their shortest paths. This paper extends flow-capturing models to optimal location of refueling facilities for alternative-fuel (alt-fuel) vehicles, such as hydrogen fuel cells or natural gas. Existing flow-capturing models assume that if a flow passes just one facility along its path, it is covered. This assumption does not carry over to vehicle refueling because of the limited range of vehicles. For refueling, it may be necessary to stop at more than one facility in order to successfully refuel the entire path, depending on the vehicle range, the path length, and the node spacing. The Flow Refueling Location Model (FRLM) optimally locates p refueling stations on a network so as to maximize the total flow volume refueled. This paper presents a mixed-integer programming formulation for the nodes-only version of the problem, as well as an algorithm for determining all combinations of nodes that can refuel a given path. A greedy-adding approach is demonstrated to be suboptimal, and the tradeoff curve between number of facilities and flow volume refueled is shown to be nonconvex.     

物流系统设施区位模型研究

本文系统介绍了以降低成本与提高服务效率为目标的传统物流系统设施区位模型即运输成本最小化模型与服务效率模型的发展与特点。作者认为确定性模型向不确定性模型演化是运输成本最小化模型发展的总趋势，服务效率模型包括以建设成本最小化为目标的完全覆盖模型和最大覆盖模型两类：在此基础上，介绍了近年来在供应链环境影响下发展而来的考虑库存成本与各级企业利益协调的库存-选址区位模型。     

Stochastic model specification search for Gaussian and partial non-Gaussian state space models

Model specification for state space models is a difficult task as one has to decide which components to include in the model and to specify whether these components are fixed or time-varying. To this aim a new model space MCMC method is developed in this paper. It is based on extending the Bayesian variable selection approach which is usually applied to variable selection in regression models to state space models. For non-Gaussian state space models stochastic model search MCMC makes use of auxiliary mixture sampling. We focus on structural time series models including seasonal components, trend or intervention. The method is applied to various well-known time series.     

Services cultural alignment in offshoring: The impact of cultural dimensions on offshoring location choices

Empirical research on the growing wave of services offshoring has examined the impact of several key factors such as wages and personnel quality on firm choices of offshore locations. However, examinations of culture in services offshoring to date have largely been confined to the relatively coarse concept of aggregate cultural differences between the home and host countries. We propose that specific cultural attributes are more closely aligned with successful service provision. We empirically examine our theoretical development of service cultural alignment and investigate the impact of cultural dimensions on the location of service offshoring projects. In addition, we examine whether Western and Asian firms have different cultural preferences in terms of the location of services offshoring projects. We find that host countries with lower levels of Hofstede's uncertainty avoidance as well as higher levels of individualism and power distance are able to attract greater numbers of service offshoring projects, even after controlling for macroeconomic, linguistic, and risk-related factors. We did not find that Western and Asian firms have different cultural preferences in this regard. We discuss implications of the findings with respect to theory, managerial practice, and governmental policy.     

A family of Markovian models of recurrent choice

This paper presents a Markovian binary choice model for a heterogeneous population using a bivariate S_BB mixing distribution. Special forms of this model include Markov models with independent parameters, Last Place Loyal, Place Loyal and Bernoulli models. The modelling framework adopted allows these special forms to be both identified and tested. Analysis of recurrent shopping trips from travel diary data from Uppsala, Sweden [Burnett (1977)] finds no Markovian adaptive behaviour.     

Intraurban variation in the price of housing

Theoretical models of spatial consumer behavior assume the existence of a housing price surface that increases with accessibility. It is often hypothesized that inadequate accessibility measures are responsible for the failure of most empirical studies to support this premise. A general accessibility measure consisting of a double power series in cartesian coordinates is developed and shown to represent a general formulation of traditional accessibility measures. This formulation is incorporated in a hedonic price regression model, and the model is estimated using census tract data for the city of Milwaukee. The hedonic prices are then used to construct intraurban housing price indexes. The results of this study provide strong support for the existence of the presumed price surface. A comparison of this new hedonic price model with traditional models suggests that the double power series formulation is a superior representation of accessibility.     

A central limit theorem for endogenous locations and complex spatial interactions

We provide a new central limit theorem (CLT) for spatial processes under weak conditions that are plausible for many economic applications in which location is endogenous. In particular, our CLT is designed for problems that have some, but not necessarily all, of the following features: (i) Agents choose the locations of observations to maximize profits, welfare, or some other objective. (ii) The objects that are chosen (e.g., stores or brands) interact with one another. For example, they can be substitutes or complements. (iii) Interaction can be complex. In particular, interaction between i and j need not depend only on the distance between the locations of i and j, but can also depend on distance to or location of other observations k, or possibly on the number of other such observations.     

Measuring the spatial accessibility to fire stations using enhanced floating catchment method

Enhancing the spatial accessibility of population to fire services is a key strategy to help improve emergency response, minimise property loss, and reduce injuries and deaths. Given its significance for fire service policy and strategic planning, we draw on small area population forecasts, fire station locations and the road network, and employ the enhanced two-step floating catchment method to compute the levels of spatial accessibility of population to fire services in relation to current and future population growth in Brisbane, Australia. Results show that lower levels of spatial accessibility to fire services exist in the most populated areas compared to those that are least populated. Further, we reveal that some areas are more likely to suffer a reduction in spatial accessibility than others. Spatial accessibility of population to fire services over the period to 2036 is likely to reduce as a consequence of rising demand for service. The identification of locales that experience lower levels of accessibility to fire services will enable fire services agencies to strategically plan infrastructure investment and help enhance the operational efficiency of emergency response.     

On the non-existence of oligopolistic equilibria in differentiated products spaces

In a large class of product differentiation models á la Hotelling, the firms' payoffs in the game involving location in the differentiated products space exclusively depends on the distance to their neighbouring firms, rather than on the firms' locations proper. This leads to a degeneracy on the firms' strategy space. Using alternative equilibrium concepts, this is shown to be the reason for the non-existence of non-cooperative equilibria, especially if the firms' technologies are not identical.     

A location-based comparison of health care services in four U.S. states with efficiency and equity

This paper examines the efficiency and equality in geographic accessibility provided by hospitals. We use the criteria efficiency, availability of the service, and equality. Quantitative measures are defined for all criteria, and are measured using a geographical information system. We then compare existing locations with optimal locations satisfying two objectives, one that minimizes hospital–patient distance, and another that captures as many patients as possible within a pre-specified time or distance. The results of our study indicate that the existing locations provide near-optimal geographic access to health care. Some potential for improvement is indicated.     

Critical infrastructure location under supporting station dependencies considerations

This paper develops a framework to locate critical infrastructure (CI) facilities to most fully capitalize on the supporting stations (SSs) they depend on for normal operation. CI facilities include health services, transportation and electricity; agencies that impact the national economy, security and the public's health and wellbeing. SSs are facilities that provide essential services for the regular operation of a CI. For instance, the power service, communication services and water supply services are SSs for Hospitals. In this paper SSs are independent from the CIs that they service and have a heterogeneous probability of failure that will cripple the dependent CI. The proposed framework ranks the SS according to its cost of providing service such that the rank-1 SS is the primary service provider and incorporates the probability of failure for the SS. The CI will be served from secondary SS if the primary fails due to a disaster. This formulation insures the continuous service to the CI from SS and determines both the optimal location of the CI and the optimal number of demands served. A mixed integer linear programming approach is applied to develop a Reliable Facility Location Problem considering Supporting Stations (RFLP-SS) to identify the optimal location to build a critical facility. In addition to that, The RFLP-SS determines the capacity of the optimally located facility and its allocated demands. This research highlights the importance of considering dependencies among the SSs that service CI. The paper presents a case study in Puerto Rico to demonstrate the applicability of the proposed framework. The case study investigates the status of health services in Puerto Rico, and identifies the optimal locations to establish new hospitals. The paper recommends 11 locations for new hospitals so that the people of Puerto Rico will be better served than they are currently.