The global system for mobile communication(GSM)is planned to meet the needs of the whole subscribers.The number of subscribers increased as the population increased due to the acceptance of GSM services by the subscri...The global system for mobile communication(GSM)is planned to meet the needs of the whole subscribers.The number of subscribers increased as the population increased due to the acceptance of GSM services by the subscribers.Thus,there should be a way to monitor base stations that will meet the increasing demand of subscribers in any area as a population surge will lead to more subscriptions.This will allow GSM network operators to serve their subscribers better and ease network congestion.This work presents a review of mobile evolution from the first generation to the fifth generation.A review of global positioning system(GPS)technology and its applications to geographic information systems(GIS)was done.The coordinates of these base stations were taken using a GPS device.These base station coordinates were then exported to QGIS for the design of the map.Thereafter,the output map was then integrated into the website.The discussions on the results followed and some useful suggestions given will go a long way to help the operators of GSM in Nigeria and in general.If the propositions given are adhered to,it will go a long way to help the operators reduce congestion on their network and thereby increase the satisfaction of the subscribers.展开更多
Landfilling is one of the most effective and responsible ways to dispose of municipal solid waste(MSW).Identifying landfill sites,however,is a challenging and complex undertaking because it depends on social,environme...Landfilling is one of the most effective and responsible ways to dispose of municipal solid waste(MSW).Identifying landfill sites,however,is a challenging and complex undertaking because it depends on social,environmental,technical,economic,and legal issues.This study aims to map the optimal sites that were environmentally suitable for locating a landfill site in Butuan City,Philippines.With reference to the policy requirements from DENR Section I,Landfill Site Identification Criteria and Screening Guidelines of National Solid Waste Management Commission,the integration of a Geographic Information System(GIS)model builder and Analytical Hierarchy Process(AHP)has been used in this study to address the aforementioned challenges related to the landfill site suitability analysis.Based on the generated sanitary landfill suitability map,results showed that Barangay Tungao(1131.42967 ha)and Florida(518.48 ha)were able to meet and consider the three(3)main components,namely economic,environmental,and physical criteria,and are highly suitable as landfill site locations in Butuan City.It is recommended that there will conduct a geotechnical evaluation,involving rigorous geological and hydrogeological assessment employing a combination of site investigation and laboratory techniques.In addition,additional specific social,ecological,climatic,and economic factors need to be considered(i.e.including impact on humans,flora,fauna,soil,water,air,climate,and landscape).展开更多
Malaria is a major health problem facing many tropical countries, including Ghana. The use of modern mechanisms to study environmental factors in malaria occurrence is imperative in malaria control efforts. The aim of...Malaria is a major health problem facing many tropical countries, including Ghana. The use of modern mechanisms to study environmental factors in malaria occurrence is imperative in malaria control efforts. The aim of this research is to investigate how malaria occurrence is influenced by environmental factors and how Geographical Information Systems (GIS) can be used as a mechanism for improving malaria control in healthcare delivery in Ghana. Environmental factors, elevation, daily temperature and daily rainfall were plotted against prevalence of M and S forms of mosquitoes using ArcGIS 10.1. Prevalence of Anopheles gambiae M was the highest at elevations of 0 m to 200 m and that of S was the highest at elevations between 200 m and 500 m. Prevalence of M was the highest at temperatures between 26.1°C - 27.6°C whilst that of S was the highest at temperatures of between 24.5°C and 26.0°C. Prevalence of M was the highest at rainfall between 10 mm and 35 mm and S was the highest at rainfall between 26 mm and 36 mm and beyond. M form was positively correlated with temperature and negatively with elevation and humidity. The S form was negatively associated with temperature and positively with elevation and rainfall. GIS models can combine with environmental data to estimate vector prevalence under environmental conditions and therefore its use is recommended in Ghana.展开更多
Demarcating distribution area of goods is often guided by the rule of thumb by business proprietors. However, this method seems to be unsuitable when the demand points increase to a certain large extent. The present w...Demarcating distribution area of goods is often guided by the rule of thumb by business proprietors. However, this method seems to be unsuitable when the demand points increase to a certain large extent. The present work attempted to convert the problem of distribution area demarcation into a localized problem of warehouseing and networking, and tried to establish district-based planning mode based on location based heuristic (LBH). Two methods were used in this study: 1) the manual method to construct the mathematical model and conduct simulation; 2) the automatic method using TransCAD software of geographical information system (GIS) for simulation. By comparing the effects of the two methods, the research provides theoretical support for business proprietors to demarcate the distribution area rationally with the application of GIS system. The results show that GIS has very good graphics construction function to replace complex text, and the automatic demarcating mode with human-machine interaction provides a good business decision-making support.展开更多
GIS relates and integrates spatial data from various sources, for storage, retrieval, analyses and display. This paper presents the analysis and mapping of Geotechnical data using natural neighbour interpolation tool ...GIS relates and integrates spatial data from various sources, for storage, retrieval, analyses and display. This paper presents the analysis and mapping of Geotechnical data using natural neighbour interpolation tool of GIS. The Campus of Hassan Usman Katsina Polytechnic Nigeria was as the study area, and Arc GIS 10.2.1 was used to perform the analyses. The study used soils samples from ten trial pit distributed within the study area and subjected to various laboratory tests. Index and engineering properties of the samples were determined. Map database developed in a GIS environment and the result of the laboratory tests stored, were analysed and displayed using GIS. The research results show maps of various soil properties. The research result provides estimated data for preliminary designing of engineering infrastructures in the area.展开更多
The lack of water resources in many regions is the main challenge for the human being and to extended investigations. Water resources controlling and management is essential in the areas depending on the seasonal rain...The lack of water resources in many regions is the main challenge for the human being and to extended investigations. Water resources controlling and management is essential in the areas depending on the seasonal rainfall. This research aims to estimate the surface water runoff for Basin of Alrakhmah Valley located in the southwestern part of Kirkuk Province in northeastern of Iraq. Analyzing of Spatial data and Digital Elevation Model (DEM) data has been conducted using Geographic Information System (GIS) to estimate the hydrological properties for the watershed valley with 158.5 km<sup>2</sup> surface area. The results showed that watershed valley type is from the fifth rank with a longitudinal shape and topography percentage of 0.568. The watershed textures found to be 3.24 and the drain density 1.5 at 3.49 river branching. Finally, the annual estimated surface water retreat according to the morpho-hydro climatic elements found to be 0.01286233 milliard cubic meter.展开更多
人文社会地理信息系统(geographical information system, GIS)源于人文科学、社会科学和地理信息科学等多个学科的交叉融合,属于自然科学与人文社会科学的学科交叉领域.本文依托南京师范大学长期开展地理信息科学与人文社会科学交叉融...人文社会地理信息系统(geographical information system, GIS)源于人文科学、社会科学和地理信息科学等多个学科的交叉融合,属于自然科学与人文社会科学的学科交叉领域.本文依托南京师范大学长期开展地理信息科学与人文社会科学交叉融合的科研和教学成果,系统分析了人文社会GIS的交叉学科特性,提出了人文社会GIS的内涵和知识体系,设计了“人文社会GIS”课程的创新教学模式,形成了有代表性的学科交叉课程教学实践案例,对于开展“新工科”和“新文科”背景下的交叉学科研究和复合型人才培养具有较好的参考价值.展开更多
为了解决工业发展导致的灌区土壤投入品残留污染问题,给出一种基于地理信息系统(geographic information system,GIS)的土壤污染监测预警系统。该系统结合VOC-PF1型传感器、STM32主控芯片和GSM通信模块,实现了高效的数据采集和通信功能...为了解决工业发展导致的灌区土壤投入品残留污染问题,给出一种基于地理信息系统(geographic information system,GIS)的土壤污染监测预警系统。该系统结合VOC-PF1型传感器、STM32主控芯片和GSM通信模块,实现了高效的数据采集和通信功能。通过反距离加权(inverse distance weighted,IDW)插值法进行空间分析,并设立预警阈值,实现对灌区土壤投入品残留污染的实时监测和预警。实验结果表明:该系统的监测精度高达98%,监测时长最高为49 s,具有很高的实用性和效率。研究结果不仅为灌区土壤投入品残留污染监测提供了有效手段,也为环境保护和农业可持续发展提供有力支持。展开更多
Ecological security defined as the creation of a condition where the physical surroundings of a community provide for the needs of its inhabitants without diminishing its natural stock,which is important for regional ...Ecological security defined as the creation of a condition where the physical surroundings of a community provide for the needs of its inhabitants without diminishing its natural stock,which is important for regional security and social stability.In recent years,land use patterns in the Changbai Mountain region have changed significantly with intensive human activities,and consequently led to increasing problems in regional ecological security.Based on the Pressure-State-Impact-Response(PSIR) model and the mathematical method of catastrophe progression supported by geographical information system(GIS),the ecological security situation of the study area under land use and cover change(LUCC) was evaluated.The results indicated that the ecological security in Changbai Mountain region varied nonlinearly,which got better from 1990 to 2000 but became worse from 2000 to 2007,the ecological security levels in Changbai Mountain region were mainly medium and medium to low during the past 17 years,with higher values of Ecological Security Index(ESI) in the central region and lower values in the east and west,the ecological security situation was more serious in the settlements and river valleys,where the LUCC was most remarkable.展开更多
The objective of this paper is to develop a GIS(Geographic Information System) database for Jiuzhaigou National Nature Reserve(Jiuzhaigou,hereafter) in China and demonstrate its application as a research tool.A cost-e...The objective of this paper is to develop a GIS(Geographic Information System) database for Jiuzhaigou National Nature Reserve(Jiuzhaigou,hereafter) in China and demonstrate its application as a research tool.A cost-effective procedure was developed to compile a variety of geographical and biological data of the study area in terms of popular GIS format such as shape files.These files were further calibrated and validated using field surveys data.The developed GIS database was used to quantify the distributions of the wildlife(amphibians,mammals,and birds) using the distances of the wildlife to the centerline of the bus-tour routes.The Pearson correlation coefficient was used to quantify the correlation in space between pairs of different wildlife using the number of habitats for given space contexts.An ArcObject-based macro was developed to perform the analysis.The results showed the majority of the habitats of wildlife are located in the proximity of the tour-bus routes with an average distance ranging from 564 to 894 m depending on types of wildlife.This indicates a possibility of the disturbance to the wildlife by human activities.The correlation coefficient of the wildlife ranged from 0.36 to 0.64 depending on pairs of wildlife,indicating some correlations in space.However,due to the limited sample size,the statistical significances need to be further investigated.This paper has successfully demonstrated the use of the GIS-based database as a research tool for environmental study.展开更多
Objective:To expound geographical information system (GIS) technology is a very important tool when it was employed to assist to present the distribution by time and place and the model of transmission of infectious d...Objective:To expound geographical information system (GIS) technology is a very important tool when it was employed to assist to present the distribution by time and place and the model of transmission of infectious disease. Methods: We illustrated the assistant decision-making support function of GIS with an example of the spatial decision support system for SARS controlling in Shaanxi province of China which was developed by us. Results: The spatial decision support system established by applying GIS technology fulfilled the needs of real-time collection and management and dissemination SARS information and of surveillance and analysis the epidemic situation of SARS. Conclusion: Occurrence and epidemic of diseases, implement prevention and intervention measures and collocation hygienic resources are all with the characteristic of the variation of time and space, therefore, GIS technology has become a powerful tool for identifying risk factors of diseases, providing clues of causation of diseases , evaluating the effects of intervention measures and drawing a health management plan.展开更多
Historical geographic information system construction echoes the call of academic development in the information era and demonstrates the in-depth advancement of history studies. In recent years, an increasing number ...Historical geographic information system construction echoes the call of academic development in the information era and demonstrates the in-depth advancement of history studies. In recent years, an increasing number of data platforms have been built to facilitate historical information storage, display, management and analysis. In such a context, the geographic information system(GIS) begins to contribute to the study of Chinese history. Its contribution is highlighted in nine areas: historical climate, fluvial landforms, town economies, rural settlements, hydraulic societies, environmental changes, ancient cities, ancient maps and HGIS-enabled research methods. The application of GIS to the study of Chinese history initiates a reform in research methods and at the same time upgrades the philosophy of history studies, facilitating the utilization of a diversity of historical data(documents, ancient maps, remote-sensing images, archaeological information, etc.) for dynamic tracing and multi-factor comprehensive research. At present, restricted by traditional disciplinary boundaries, the construction of HGIS platforms remains slow and insufficient, making it difficult to extensively apply GIS to the study of Chinese history.展开更多
Average credit scores for people in the United States (US) differ from state to state. Some states have high, and some states have low average credit scores. Since lenders and employers use credit scores to make loa...Average credit scores for people in the United States (US) differ from state to state. Some states have high, and some states have low average credit scores. Since lenders and employers use credit scores to make loan and employment decisions, people living in states where average credit scores are high should experience the benefits of living where credit scores tend to allow more favorable loan and employment decisions. Although credit scores are the direct result of credit histories, credit histories may be impacted by demographic factors. If the demographic factors that impact credit histories are identified, ways to improve credit scores are likely to be discovered and available to people and state government policymakers. This study looks for demographic factors to indirectly explain the average credit scores for people living in each state of the US. The methodology includes statistical analyses and geographic information systems (GIS) mapping. Statistical analyses provide evidence to suggest that state average credit scores are explained by the demographic factors of education, family, income, and health. GIS mapping reveals clusters of states with similar demographics and credit scores.展开更多
文摘The global system for mobile communication(GSM)is planned to meet the needs of the whole subscribers.The number of subscribers increased as the population increased due to the acceptance of GSM services by the subscribers.Thus,there should be a way to monitor base stations that will meet the increasing demand of subscribers in any area as a population surge will lead to more subscriptions.This will allow GSM network operators to serve their subscribers better and ease network congestion.This work presents a review of mobile evolution from the first generation to the fifth generation.A review of global positioning system(GPS)technology and its applications to geographic information systems(GIS)was done.The coordinates of these base stations were taken using a GPS device.These base station coordinates were then exported to QGIS for the design of the map.Thereafter,the output map was then integrated into the website.The discussions on the results followed and some useful suggestions given will go a long way to help the operators of GSM in Nigeria and in general.If the propositions given are adhered to,it will go a long way to help the operators reduce congestion on their network and thereby increase the satisfaction of the subscribers.
文摘Landfilling is one of the most effective and responsible ways to dispose of municipal solid waste(MSW).Identifying landfill sites,however,is a challenging and complex undertaking because it depends on social,environmental,technical,economic,and legal issues.This study aims to map the optimal sites that were environmentally suitable for locating a landfill site in Butuan City,Philippines.With reference to the policy requirements from DENR Section I,Landfill Site Identification Criteria and Screening Guidelines of National Solid Waste Management Commission,the integration of a Geographic Information System(GIS)model builder and Analytical Hierarchy Process(AHP)has been used in this study to address the aforementioned challenges related to the landfill site suitability analysis.Based on the generated sanitary landfill suitability map,results showed that Barangay Tungao(1131.42967 ha)and Florida(518.48 ha)were able to meet and consider the three(3)main components,namely economic,environmental,and physical criteria,and are highly suitable as landfill site locations in Butuan City.It is recommended that there will conduct a geotechnical evaluation,involving rigorous geological and hydrogeological assessment employing a combination of site investigation and laboratory techniques.In addition,additional specific social,ecological,climatic,and economic factors need to be considered(i.e.including impact on humans,flora,fauna,soil,water,air,climate,and landscape).
文摘Malaria is a major health problem facing many tropical countries, including Ghana. The use of modern mechanisms to study environmental factors in malaria occurrence is imperative in malaria control efforts. The aim of this research is to investigate how malaria occurrence is influenced by environmental factors and how Geographical Information Systems (GIS) can be used as a mechanism for improving malaria control in healthcare delivery in Ghana. Environmental factors, elevation, daily temperature and daily rainfall were plotted against prevalence of M and S forms of mosquitoes using ArcGIS 10.1. Prevalence of Anopheles gambiae M was the highest at elevations of 0 m to 200 m and that of S was the highest at elevations between 200 m and 500 m. Prevalence of M was the highest at temperatures between 26.1°C - 27.6°C whilst that of S was the highest at temperatures of between 24.5°C and 26.0°C. Prevalence of M was the highest at rainfall between 10 mm and 35 mm and S was the highest at rainfall between 26 mm and 36 mm and beyond. M form was positively correlated with temperature and negatively with elevation and humidity. The S form was negatively associated with temperature and positively with elevation and rainfall. GIS models can combine with environmental data to estimate vector prevalence under environmental conditions and therefore its use is recommended in Ghana.
基金Funded by Natural Science Foundation of Zhejiang Province of China (No. Y6090417)Social Sciences Foundation of the Ministry of Education of China (No. 09YJA630143)
文摘Demarcating distribution area of goods is often guided by the rule of thumb by business proprietors. However, this method seems to be unsuitable when the demand points increase to a certain large extent. The present work attempted to convert the problem of distribution area demarcation into a localized problem of warehouseing and networking, and tried to establish district-based planning mode based on location based heuristic (LBH). Two methods were used in this study: 1) the manual method to construct the mathematical model and conduct simulation; 2) the automatic method using TransCAD software of geographical information system (GIS) for simulation. By comparing the effects of the two methods, the research provides theoretical support for business proprietors to demarcate the distribution area rationally with the application of GIS system. The results show that GIS has very good graphics construction function to replace complex text, and the automatic demarcating mode with human-machine interaction provides a good business decision-making support.
文摘GIS relates and integrates spatial data from various sources, for storage, retrieval, analyses and display. This paper presents the analysis and mapping of Geotechnical data using natural neighbour interpolation tool of GIS. The Campus of Hassan Usman Katsina Polytechnic Nigeria was as the study area, and Arc GIS 10.2.1 was used to perform the analyses. The study used soils samples from ten trial pit distributed within the study area and subjected to various laboratory tests. Index and engineering properties of the samples were determined. Map database developed in a GIS environment and the result of the laboratory tests stored, were analysed and displayed using GIS. The research results show maps of various soil properties. The research result provides estimated data for preliminary designing of engineering infrastructures in the area.
文摘The lack of water resources in many regions is the main challenge for the human being and to extended investigations. Water resources controlling and management is essential in the areas depending on the seasonal rainfall. This research aims to estimate the surface water runoff for Basin of Alrakhmah Valley located in the southwestern part of Kirkuk Province in northeastern of Iraq. Analyzing of Spatial data and Digital Elevation Model (DEM) data has been conducted using Geographic Information System (GIS) to estimate the hydrological properties for the watershed valley with 158.5 km<sup>2</sup> surface area. The results showed that watershed valley type is from the fifth rank with a longitudinal shape and topography percentage of 0.568. The watershed textures found to be 3.24 and the drain density 1.5 at 3.49 river branching. Finally, the annual estimated surface water retreat according to the morpho-hydro climatic elements found to be 0.01286233 milliard cubic meter.
文摘人文社会地理信息系统(geographical information system, GIS)源于人文科学、社会科学和地理信息科学等多个学科的交叉融合,属于自然科学与人文社会科学的学科交叉领域.本文依托南京师范大学长期开展地理信息科学与人文社会科学交叉融合的科研和教学成果,系统分析了人文社会GIS的交叉学科特性,提出了人文社会GIS的内涵和知识体系,设计了“人文社会GIS”课程的创新教学模式,形成了有代表性的学科交叉课程教学实践案例,对于开展“新工科”和“新文科”背景下的交叉学科研究和复合型人才培养具有较好的参考价值.
基金supported by the National Key Technology R&D Program of China under Grant No.2013BAK05B01the National Natural Science Foundation of China under Grant No.41371495+1 种基金the National Grand Fundamental Research 973 Program of China under Grant No.2010CB951102the National Key Technology R&D Program of China under Grant No.2011BAD32B00-04
文摘Ecological security defined as the creation of a condition where the physical surroundings of a community provide for the needs of its inhabitants without diminishing its natural stock,which is important for regional security and social stability.In recent years,land use patterns in the Changbai Mountain region have changed significantly with intensive human activities,and consequently led to increasing problems in regional ecological security.Based on the Pressure-State-Impact-Response(PSIR) model and the mathematical method of catastrophe progression supported by geographical information system(GIS),the ecological security situation of the study area under land use and cover change(LUCC) was evaluated.The results indicated that the ecological security in Changbai Mountain region varied nonlinearly,which got better from 1990 to 2000 but became worse from 2000 to 2007,the ecological security levels in Changbai Mountain region were mainly medium and medium to low during the past 17 years,with higher values of Ecological Security Index(ESI) in the central region and lower values in the east and west,the ecological security situation was more serious in the settlements and river valleys,where the LUCC was most remarkable.
基金sponsored by the Natural Science Foundation of China(Grant No.41101514)111 Project+4 种基金New Faculty Start-up Funds of Sichuan University(Grant No.JS20100324507093)the New Century Talent Support Program of the Ministry of Education of China(Grant No.NCET10-0578)International Science & Technology Cooperation Program(Grant No.2012DFG91520)Key Projects of National Science & Technology Pillar Program in the 12th 5 Years(Grant No.2013BAJ11B01)the Jiuzhaigou International Laboratory of Sichuan University,the GIS Center, and the Sustainability Research and Education Center of Sichuan University
文摘The objective of this paper is to develop a GIS(Geographic Information System) database for Jiuzhaigou National Nature Reserve(Jiuzhaigou,hereafter) in China and demonstrate its application as a research tool.A cost-effective procedure was developed to compile a variety of geographical and biological data of the study area in terms of popular GIS format such as shape files.These files were further calibrated and validated using field surveys data.The developed GIS database was used to quantify the distributions of the wildlife(amphibians,mammals,and birds) using the distances of the wildlife to the centerline of the bus-tour routes.The Pearson correlation coefficient was used to quantify the correlation in space between pairs of different wildlife using the number of habitats for given space contexts.An ArcObject-based macro was developed to perform the analysis.The results showed the majority of the habitats of wildlife are located in the proximity of the tour-bus routes with an average distance ranging from 564 to 894 m depending on types of wildlife.This indicates a possibility of the disturbance to the wildlife by human activities.The correlation coefficient of the wildlife ranged from 0.36 to 0.64 depending on pairs of wildlife,indicating some correlations in space.However,due to the limited sample size,the statistical significances need to be further investigated.This paper has successfully demonstrated the use of the GIS-based database as a research tool for environmental study.
基金Supported by the Sci & Tech Development Foundation of Shaanxi province(2003K10G61)
文摘Objective:To expound geographical information system (GIS) technology is a very important tool when it was employed to assist to present the distribution by time and place and the model of transmission of infectious disease. Methods: We illustrated the assistant decision-making support function of GIS with an example of the spatial decision support system for SARS controlling in Shaanxi province of China which was developed by us. Results: The spatial decision support system established by applying GIS technology fulfilled the needs of real-time collection and management and dissemination SARS information and of surveillance and analysis the epidemic situation of SARS. Conclusion: Occurrence and epidemic of diseases, implement prevention and intervention measures and collocation hygienic resources are all with the characteristic of the variation of time and space, therefore, GIS technology has become a powerful tool for identifying risk factors of diseases, providing clues of causation of diseases , evaluating the effects of intervention measures and drawing a health management plan.
基金a staged research result of “Silk Road-themed Historical Geographic Information System Construction”(14ZDB031)a major program funded by National Social Sciences Fund
文摘Historical geographic information system construction echoes the call of academic development in the information era and demonstrates the in-depth advancement of history studies. In recent years, an increasing number of data platforms have been built to facilitate historical information storage, display, management and analysis. In such a context, the geographic information system(GIS) begins to contribute to the study of Chinese history. Its contribution is highlighted in nine areas: historical climate, fluvial landforms, town economies, rural settlements, hydraulic societies, environmental changes, ancient cities, ancient maps and HGIS-enabled research methods. The application of GIS to the study of Chinese history initiates a reform in research methods and at the same time upgrades the philosophy of history studies, facilitating the utilization of a diversity of historical data(documents, ancient maps, remote-sensing images, archaeological information, etc.) for dynamic tracing and multi-factor comprehensive research. At present, restricted by traditional disciplinary boundaries, the construction of HGIS platforms remains slow and insufficient, making it difficult to extensively apply GIS to the study of Chinese history.
文摘Average credit scores for people in the United States (US) differ from state to state. Some states have high, and some states have low average credit scores. Since lenders and employers use credit scores to make loan and employment decisions, people living in states where average credit scores are high should experience the benefits of living where credit scores tend to allow more favorable loan and employment decisions. Although credit scores are the direct result of credit histories, credit histories may be impacted by demographic factors. If the demographic factors that impact credit histories are identified, ways to improve credit scores are likely to be discovered and available to people and state government policymakers. This study looks for demographic factors to indirectly explain the average credit scores for people living in each state of the US. The methodology includes statistical analyses and geographic information systems (GIS) mapping. Statistical analyses provide evidence to suggest that state average credit scores are explained by the demographic factors of education, family, income, and health. GIS mapping reveals clusters of states with similar demographics and credit scores.