GEOGRAPHIC INFORMATION SYSTEM

Transcription

1 GEOGRAPHIC INFORMATION SYSTEM Submitted by: FELCAR NUÑEZ DANN ANGELO ALBAÑO Masterands Submitted to: MR. DOMINO PUSON Professor

2 This report will cover the following information about Geographic Information System: 1. Definition of Geographic Information Systems (GIS) 2. History of GIS 3. Type of data utilized by GIS 4. GIS operations and functions 5. Elements of GIS 6. GIS in Healthcare 7. Nursing and GIS 8. GIS in Health Research 9. Limitations of GIS in Health Research 10. Advantages of GIS in healthcare 11. Current limitations of GIS in healthcare GEOGRAPHIC INFORMATION SYSTEMS (GIS) DEFINITION: GIS is a system of hardware and software used for storage, retrieval, mapping, and analysis of geographic data. Practitioners also regard the total GIS as including the operating personnel and the data that go into the system. Spatial features are stored in a coordinate system (latitude/longitude, state plane, UTM, etc.), which references a particular place on the earth.

3 Descriptive attributes in tabular form are associated with spatial features. Spatial data and associated attributes in the same coordinate system can then be layered together for mapping and analysis. GIS can be used for scientific investigations, resource management, and development planning. GIS differs from CAD and other graphical computer applications in that all spatial data is geographically referenced to a map projection in an earth coordinate system. For the most part, spatial data can be "re-projected" from one coordinate system into another, thus data from various sources can be brought together into a common database and integrated using GIS software. Boundaries of spatial features should "register" or align properly when reprojected into the same coordinate system. Another property of a GIS database is that it has "topology," which defines the spatial relationships between features. The fundamental components of spatial data in a GIS are points, lines (arcs), and polygons. When topological relationships exist, you can perform analyses, such as modeling the flow through connecting lines in a network, combining adjacent polygons that have similar characteristics, and overlaying geographic features. HISTORY: In 1854, John Snow depicted a cholera outbreak in London using points to represent the locations of some individual cases, possibly the earliest use of the geographic method. His study of the distribution of cholera led to the source of the disease, a contaminated water pump (the Broad Street Pump, whose handle he had disconnected, thus terminating the outbreak) within the heart of the cholera outbreak. The year 1960 saw the development of the world's first true operational GIS in Ottawa, Ontario, Canada by the federal Department of Forestry and Rural Development. Developed by Dr. Roger

4 Tomlinson, it was called the Canada Geographic Information System (CGIS) and was used to store, analyze, and manipulate data collected for the Canada Land Inventory (CLI) an effort to determine the land capability for rural Canada by mapping information about soils, agriculture, recreation, wildlife, waterfowl, forestry and land use at a scale of 1:50,000. A rating classification factor was also added to permit analysis. CGIS lasted into the 1990s and built a large digital land resource database in Canada. It was developed as a mainframe-based system in support of federal and provincial resource planning and management. Its strength was continent-wide analysis of complex datasets. The CGIS was never available in a commercial form. In 1964, Howard T. Fisher formed the Laboratory for Computer Graphics and Spatial Analysis at the Harvard Graduate School of Design (LCGSA ), where a number of important theoretical concepts in spatial data handling were developed, and which by the 1970s had distributed seminal software code and systems, such as 'SYMAP', 'GRID' and 'ODYSSEY' that served as sources for subsequent commercial development to universities, research centers and corporations worldwide. By the early 1980s, M&S Computing (later Intergraph) along with Bentley Systems Incorporated for the CAD platform, Environmental Systems Research Institute (ESRI), CARIS (Computer Aided Resource Information System) and ERDAS (Earth Resource Data Analysis System) emerged as commercial vendors of GIS software, successfully incorporating many of the CGIS features, combining the first generation approach to separation of spatial and attribute information with a second generation approach to organizing attribute data into database structures. In parallel, the development of two public domain systems (MOSS and GRASS GIS) began in the late 1970s and early 1980s. By the end of the 20th century, the rapid growth in various systems had been consolidated and standardized on relatively few platforms and users were beginning to explore the concept of

5 viewing GIS data over the Internet, requiring data format and transfer standards. More recently, a growing number of free, open-source GIS packages run on a range of operating systems and can be customized to perform specific tasks. Increasingly geospatial data and mapping applications are being made available via the World Wide Web. TYPE OF DATA UTILILIZED BY GIS TABULAR DATA Tabular data consists of attribute tables that define the parameters of the map features. There is really no limit to what the tables can contain, whether Boolean strings (True/False), Text, or Numeric data. For example, a Boolean entry in a cities table may define whether or not each city is a national capital. A text entry may have the city's name, or the archaeological period in which it flourished. A numeric entry could have population figures or lat/long coordinates. The advantage of the relational database system is that the different columns can be sorted and selected according to the user's need. These selections then appear highlighted on the map.

6 SPATIAL DATA Spatial data places the features on the map. The coordinates of a point are the most obvious example of this, but it also incorporates projection systems, line and polygon attributes, and other information. There are two main classes of spatial data: vector and raster. Vector Data - Most work archaeologists do in GIS is based in vector data. This system of recording features is based on the interaction between arcs and nodes, represented by points, lines, and polygons. A point is a single node, a line is two nodes with an arc between them, and

7 a polygon is a closed group of three or more arcs. With these three elements, it is possible to record most all necessary information. Points represent discrete locations on the ground. Either these are true points, such as the point marked by a USGS brass cap, such as a section corner, or they may be virtual points, based on the scale of representation. For example, a city's location on a driving map of the United States is represented by a point, even though in reality a city has area. As the map's scale increases, the city will soon appear as a polygon. Beyond a certain scale of zoom (i.e., when the map's extent is completely within the city), there will be no representation of the city at all; it will simply be the background of the map. Here is a view of the Puget Sound area with airports. The airports are stored as points within the GIS. Lines represent linear features, such as rivers, roads and transmission cables. Here are major roads in the Puget Sound region, along with line attributes. In ArcGIS, lines are also known as "arcs," hence the name "ArcGIS." Each line is composed of a number of

8 different coordinates, which make up the shape of the line, as well as the tabular record for the line vector feature. Polygons form bounded areas. Polygons are formed by bounding arcs, which keep track of the location of each polygon, as shown in this image:

9 Raster Data - Raster data is characterized by pixel values. Basically, a raster file is a giant table, where each pixel is assigned a specific value from 0 to 255. The meaning behind these values is specified by the user- they can represent elevations, temperatures, hydrography, etc. Satellite imagery uses raster data to record different wavelengths of light. Raster data is advantageous to vector data in constructing 3D images, as the values for every pixel are calculated through a process called interpolation. In ArcMap, it is possible to control what type of interpolation method is used when converting from vector to raster data. Other programs, such as Erdas Imagine, are tailored specifically to raster data and may be more appropriate for certain projects

10 GIS OPERATIONS AND FUNCTIONS Data Input Data input covers the range of operations by which spatial data from maps, remote sensors, and other sources are transformed into a digital format. Among the different devices commonly used for this operation are keyboards, digitizers, scanners, CCTS, and interactive terminals or visual display units (VDU). Given its relatively low cost, efficiency, and ease of operation, digitizing constitutes the best data input option for development planning purposes.

11 Two different types of data must be entered into the GIS: geographic references and attributes. Geographic reference data are the coordinates (either in terms of latitude and longitude or columns and rows) which give the location of the information being entered. Attribute data associate a numerical code to each cell or set of coordinates and for each variable, either to represent actual values (e.g., 200 mm of precipitation, 1,250 meters elevation) or to connote categorical data types (land uses, vegetation type, etc.). Data input routines, whether through manual keyboard entry, digitizing, or scanning, require a considerable amount of time. Data Storage Data storage refers to the way in which spatial data are structured and organized within the GIS according to their location, interrelationship, and attribute design. Computers permit large amounts of data to be stored, either on the computer's hard disk or in portable diskettes. Data Manipulation and Processing Data manipulation and processing are performed to obtain useful information from data previously entered into the system. Data manipulation embraces two types of operations: (1) operations needed to remove errors and update current data sets (editing); and (2) operations using analytical techniques to answer specific questions formulated by the user. The manipulation process can range from the simple overlay of two or more maps to a complex extraction of disparate pieces of information from a wide variety of sources. Data Output Data output refers to the display or presentation of data employing commonly used output formats that include maps, graphs, reports, tables, and charts, either as a hard-copy, as an

12 image on the screen, or as a text file that can be carried into other software programs for further analysis. ELEMENTS OF A GIS Hardware and Software Components Hardware components of a basic GIS work station consist of: (1) a central processing unit (CPU) where all operations are performed; (2) a digitizer, which consists of a tablet or table where analog data are converted to digital format; (3) a keyboard by which instructions and commands as well as data can be entered; (4) a printer or plotter to produce hard copies of the desired output; (5) a disk drive or tape drive used to store data and programs, for reading in data and for communicating with other systems; and (6) a visual display unit (VDU) or monitor where information is interactively displayed. Several GIS software packages are available representing a very broad range of cost and capability. Users and Users' Needs Planners need to carefully evaluate their GIS needs and proposed applications before taking the decision to acquire an install a GIS. Once a positive conclusion has been reached, its hardwaresoftware configuration should be designed based on those needs and applications and within the constraints posed by the financial and human resources available to operate the system. It is possible that the costs of establishing a GIS exceed the benefits to a single agency. Under these circumstances, it is worthwhile determining if several agencies might share the GIS. The potential users must agree on the data to be compiled, the data formats, standards of accuracy, etc. As a result, the data requirements of a variety of users are made compatible, and the value of the data increases commensurately.

13 Sharing information has its costs as well as benefits. Negotiating with other users can be a painful task, and compromises inevitably ensure that no one user will get the equipment most precisely suited to his uses. In this regard, it is important to establish a comfortable working relationship among sharers. Information and Information Sources General reference maps and information on natural hazards and natural resources should form a "library of knowledge" for any GIS. Virtually all countries have topographic maps, road maps, generalized soils maps, some form of climate information, and at least the locational component of natural hazards information (e.g. location of active volcanoes, fault lines, potential flood areas, areas of common occurrence of landslides, areas of past tsunami occurrence, etc.). Natural hazards locational data can be made compatible in a GIS with previously collected information about natural resources, population, and infrastructure, to provide planners with the wherewithal for a preliminary evaluation of the possible impacts of natural events. GEOGRAPHIC INFORMATION SYSTEMS IN HEALTH AND HEALTHCARE GIS have many potential applications in studying geographically differentiated health and healthcare phenomena and changes in those phenomena over time, for example, cardiovascular disease in a given community. Traditionally, two broad types of GIS applications can be distinguished, which also reflect the two traditions in health geography (geography of disease and geography of healthcare systems), namely (1) health outcomes and epidemiology applications and (2) healthcare delivery (services) applications.

14 GIS can help health care professionals, public health officials, and community members to identify potential environmental risks related to the health outcomes and to support decision making for allocation of scarce disease prevention resources in high-risk areas. Given the important role that environmental health risks can play in public health, it is critical that community/public health nurses begin to integrate environmental health assessment skills into their professional practices by creating assessment and analytic tools to be used at the local and community-based level. A simple community survey using GIS can be an effective means to raise awareness about environmental health risk factors and utilizing GIS mapping tools can further enhance the accessibility of the combined exposure and health information for both lay and professional audiences. Moreover, GIS also play an important role in the following: profiling and understanding the varying needs of target communities; profiling their environment and health and social services available to them; linking and using such information for planning, optimizing, and targeting suitable health and social care services (geographically accessible physical services-"fair access for all") and well-tailored intervention programs to those communities (eg, consumer health information, self-help and self-care programs); continually monitoring, assessing, and tweaking such interventions during their execution; testing different "what if" scenarios before making any financial commitments; and ascribing priorities in a climate of finite resources. Another use of GIS is in emergency situations, for example, in dealing with bioterrorism, especially when combined with geographically enabled syndromic surveillance systems such as RODS (Realtime Outbreak and Disease Surveillance system).

15 NURSING AND GEOGRAPHIC INFORMATION SYSTEMS Some of the uses of GIS in nursing include the following: supporting academic practice, faculty outreach, and educational initiatives at a school of nursing; visualizing nursing workforce distribution for policy evaluation; conducting community assessment and nursing research; conducting health intervention research in diabetes; providing public health nursing education and practice; and designing population-based health interventions. Understanding of GIS is essential for nursing science to continue to evolve in the 21st century. The integration of geography into nursing education, can aid in both for understanding the geographic factors that influence nursing education outcomes and providing students with insights about core subjects in the nursing curriculum. The key advantage that information systems offer is the ability to link data systems in a way that gives us a much clearer picture about the context in which healthcare is delivered. To take the example of diabetes, geographical data have identified that prescribing practices and collection/dispensing of self-testing glucose strips vary widely across areas of different population density. In the current climate of increased emphasis on self-management in longterm conditions, GIS can enable us to provide (or at least aim for) self-care support best tailored to the geographical location of the patient and the type/severity of disease. In this context, GIS also provide an ideal tool to facilitate integration of service delivery and service evaluation. GIS allow us to examine questions such as "what would happen if community nurses introduce telephone or Web-based support for patients with diabetes recently discharged from hospital?" The various facets of this intervention (availability of telephone services, availability of broadband Internet, relative costs and reliability of these services, socioeconomic data) could be mapped by geographical location, and a decision could be made about feasibility of the service.

16 GIS is able to assist nursing as a science as it continues to grow increasingly global in nature, ever-widening what is envisioned by the person and the environment. Geography, cartography, and information sciences all lend themselves to the ever-widening boundaries of nursing, both physical and theoretical in nature, and should not be overlooked. GIS tools and technology are new ways of incorporating these global realms into nursing science and research, and ultimately into practice. GIS IN HEALTH RESEARCH It is not surprising, then, that health-related fields would find GIS useful. GIS is a tool for analyzing spatial data, and there are many aspects of health research that analyze the spatial setting of quantitative phenomena. Generally speaking, there are 2 broad areas where health fields use GIS. They are, first, the geography of disease and health, and second, the geography of healthcare. The geography of disease and health involves describing and analyzing illness spatially. It is mainly interested in aspects of disease such as spatial clustering, or associations between disease and elements of the environment. For instance, mapping of certain cancers, traumatic injuries, and deaths can be used to determine areas of needed patient education for health promotion, prevention, and care. The second aspect of health research that typically uses GIS is the geography of healthcare. Health resources have to be located somewhere, and this area uses GIS to evaluate the spatial aspect of needs for healthcare and spatial aspects of healthcare provision. Researchers may look for places where healthcare needs were not being met, and where people travelled long distances to get care.

17 In a unique application of GIS, the National Indian Council on Aging (NICOA) mapped American Indian elders. NICOA produced documents, one of which was a map of the United States, with each point on the map representing each American Indian elder. The council reported that this was the first time GIS was used to map a minority population for healthcare implications. The study went on to describe and locate available relevant services as well as several disease processes present, such as diabetes. This was an effort that utilized both types of GIS in health approaches. The use of GIS in healthcare is likely to increase in the foreseeable future. Demographic and financial pressures on healthcare systems are encouraging greater emphasis on measuring health needs accurately and managing them in ways that are both clinically effective and costeffective. Of course, the desired nursing outcome to the use of such a tool is increasing the understanding of space and time as they relate to access and use. Increasing pressures of chronic conditions across all age groups necessitate an understanding of not only who your patient is, but also where and how far, and the environmental impact of that time and space on health. LIMITATIONS OF GIS IN HEALTH RESEARCH As with any tool it is often wise to gain an understanding of its intended uses and possible problems. There are several notable pitfalls in using GIS in a research project and several will be mentioned here, following the stages of a typical study. In conceptualizing a study that utilizes GIS, it is important to recognize that GIS used by non experts can potentially create misleading results due to the complexities of geographic data quality and scale, as well as more subtle issues related to misleading maps. This is where creating nontraditional (ie, out of academic health fields) interdisciplinary partnerships is important until proficiency can be attained. A second important conceptual concern is the fact that GIS is not well-equipped to handle temporal data, and is best suited for providing a current snapshot of a phenomenon. This is a

18 significant concern in many fields, including those related to health. However, as in the study underway by the authors, this is overcome by overlaying longitudinal snapshots to see past patterns and hopefully be able to more accurately predict the future map. In the second stage of a research project-data collection-researchers should consider issues of cost and availability. Although free and low-cost data are becoming more available every year, quite often the data needed for a study are either expensive to obtain, or do not yet exist. For instance, the authors had to create the database from the census for the map in Figure 5. It did not come ready-made for importing. However, now the last 2 censuses are readily available in forms compatible for GIS use. In the final 2 stages, methodology and analysis, there are several related pitfalls worth considering. Issues of cause and effect are important in all fields, though GIS was initially designed for cataloging data, not for analyzing causes. There is a tendency to believe that because computers are powerful tools, whatever emerges from them is necessarily true. But just because 2 things coincide in space does not mean that one causes the other, even if they appear together on a wonderfully expressive map. Finally, there are social, ethical, and cultural issues to consider. Models such as GIS inherently simplify, which can be useful in grasping ideas, but can also be problematic when studying the complexities of humans. An all-powerful GIS that knows all of your whereabouts and activities would not only threaten privacy, but also would not be an optimum tool for understanding culture, society, and individual values in isolation of other techniques. This is but another compelling reason to add nursing's caring voice to this tool as an advocate for person within the environment whether community or health related. ADVANTAGES OF GIS TECHNOLOGY IN HEALTHCARE

19 Several advantages of GIS technology for public health practice, planning, and research are as follows: 1) GIS technology improves the ability of practitioners, planners, and researchers to organize and link datasets (for example, by using geocoded addresses or geographic boundaries). Geography provides a near-universal link for sorting and integrating records from multiple information sources into a more coherent whole. This ability to link datasets can help public health practitioners plan more cost-effective interventions. For example, suppose that a childhood lead poisoning prevention program could access residential databases maintained by the tax assessor's office and map the street addresses of houses built before 1950 (when lead-based paint was commonly used). Suppose that the prevention program could also access hospital and managed care plan electronic databases to identify street addresses for new births. Combining these datasets, the program could apply GIS technology to identify infants at high risk for exposure to lead-based paint and send a public health worker to follow up with specific households. By matching the addresses of these infants to a street map (from a "topologically integrated geographic encoding and referencing" [TIGER] file), using the "address-match" and "route-scheduling" functions of GIS software, the health worker can implement and efficient schedule of household visitations. 2) GIS technology provides public health practitioners and researchers with several new types of data. For example, with GIS technology, local public health departments can use global positioning systems (GPS) to receive signals from satellites to determine latitude-longitude coordinates for point locations not found in TIGER files, such as rural residences, wells, and septic tanks. Public health practitioners can also use digital imagery from satellites or aerial photos to add details to (or improve the accuracy of) a mapping project. If a sequence of digital images for a small area of interest is available, automated change detection can be used to observe changes over time, such as the

20 addition of housing developments, roads, and landfills and other changes in land use and land cover. Public health practitioners can also begin to explore the utility of data collected by marketing firms about consumer spending patterns, retail expenditures, and lifestyle segmentation profile. 3) GIS technology encourages the formation of data partnerships and data sharing at the community level. For example, to develop a map of motor vehicle injuries and fatalities in a community, a local public health department could develop data partnerships with the Department of Transportation (for information about traffic flow and accidents), local ambulance services (for information about injuries requiring transportation by ambulance to hospital emergency rooms), and the Medical Examiner's office (for information about fatalities). Some GIS projects may be feasible only if all parts of local government join together and contribute (for example, developing a regional data warehouse or obtaining digital aerial photos or satellite images for an entire region). 4) Compared with tables and charts, maps developed using GIS technology can be an extremely effective tool to help community decision makers visualize and understand a public health problem. In addition, action is more likely when the decision maker can see on a map that a problem is occurring in his or her "backyard." GIS technology enables detailed maps to be generated with relative speed and ease. In turn, this provides public health practitioners with the ability to provide quick responses to questions or concerns raised in a community meeting, for example, by preparing supplemental maps or by displaying more information about a point on the map during the course of the meeting. CURRENT LIMITATIONS OF GIS IN HEALTHCARE

21 Some of the current limitations of GIS from a public health perspective are as follows: 1) Community health planning and other public health applications remains a relatively underdeveloped marketplace niche for GIS technology. 2) Current, accurate, low-cost base street maps are essential for epidemiologic uses. Without an up-to-date base street map, for example, a public health practitioner investigating a disease outbreak may have to spend considerable extra time and effort to digitize the locations of cases or may not be able to map all case reports. Current and accurate base street maps are especially needed for urban areas with high growth and for those rural areas where residents only have post office box addresses. 3) Practitioners, planners, and researchers, and especially state and local public health department staff, need training and user support in GIS technology, data, and epidemiologic methods in order to use GIS technology appropriately and effectively. The cost of training programs offered by commercial GIS vendors can be a financial burden for a small local public health agency or individual practitioner. GIS training programs specifically custom-designed for public health professionals are still relatively limited or in the early stages of development. The time required for training can be a severe challenge for organizations in which demands on personnel are already high. Another drawback is that public health professional specialties currently do not recognize continuing education credit for individuals who participate in GIS software training. 4) Statistical and epidemiological methods need to be developed to protect individual and household confidentiality. Even if a single database may appear to have effective confidentiality safeguards, when several databases are linked within a geographic information system, the "sum" may be less well protected than the "parts." A false

22 identification may be just as damaging to an individual as a correct identification that is not kept confidential. 5) GIS software continues to evolve rapidly; typically, a new iteration (or upgrade) is released about every 18 months. Every software package has its strengths and weaknesses. Current prices for some GIS products (in particular, for Web-enabled GIS applications and for neighborhood lifestyle segmentation datasets) remain a potential barrier. In addition, costs for maintenance and upgrades can be substantial. 6) The technology to prepare and display maps on the Web is still in the very early stages of development. Models and methods for Web-enabled GIS technology need to be developed for public health applications and field tested. Full GIS capability on the Web is a considerable technical challenge because GIS software has only recently started to be developed using Web-accessible programming languages and the size of GIS map images and data files can be large and significantly slow access and display functions over the Web. Spatial statistical software programs will also need to be developed for use with these Web-enabled GIS applications. REFERENCES:

23 envirn.umaryland.edu/.../geographic%20information%20systems%20a%20new%20tool%20for %20 ing_workflow_and.12.aspx