October 1995 // Volume 33 // Number 5 // Tools of the Trade // 5TOT2

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Determining Need for a Geographic Information System (GIS)

A user's need for a geographic information system (GIS) is dependent on having data with location as a characteristic as well as location being of significance to the user. Appropriate tools should be used for appropriate issues. Many potential GIS users are entranced by the graphic nature of the technology and fail to comprehend the application of the technology to their needs. Potential users should (a) identify the spatial components of their data, (b) determine if the spatial character of the data is significant in the data analysis, and (c) understand the basic concepts of GIS before approaching commercial vendors about specific GIS products.

Scott A. Samson
Assistant Extension Professor
Department of Sociology
University of Kentucky
Lexington, Kentucky
Internet address: ssamson@ukcc.uky.edu

As with the introduction of any new technology, there may be a period where "technological euphoria" captures a person's spirit while dulling the senses of practicality. Occasionally, this can result in an impulse decision and then days, weeks, or even months of regret. A current trend in information technology is the adoption of a geographic information system, or GIS, to improve the acquisition, management and analysis of spatial (geographic) data. However, the possession of a computer hardware and software system does not ensure successful application. Appropriate tools should be selected for appropriate tasks. How do users determine if a GIS would be of benefit in reaching their objective?

Understanding a GIS

Before assessing the need for a GIS, it is important that the general concepts of geographic information systems be understood. A GIS is more than the integration of computer hardware and software. It is the acquisition, management, analysis, and display of data that have geographic location as an important characteristic. Data that have a spatial character are usually displayed in the form of maps. For example, the level of nitrates found in a water sample by itself does not have geographic character. However, the location of the site where the water sample was obtained is important when viewed geographically relative to other features around the sampling site, such as proximity to potable water sources.

A GIS is also designed to recognize that there is more than one feature or activity that occupies the same geographic space. For example, a soil type may occupy some of the same area as that of a plant community. Both occupy similar space and, subsequently, can be delineated and mapped as two distinct spatial distributions. The ability to analyze coincidental and proximal (nearness) relations of features that occupy the same or nearly the same geographic space is what makes a GIS unique from conventional business relational database systems.

Not only is location important but also the manner in which location relates to a specific position on the surface of the earth. There are several earth-based coordinate systems used to define geographic location, such as latitude/longitude, Universal Transverse Mercator (UTM), and state plane. Using defined coordinate systems allows geographic data from different sources to be registered spatially with each other. Arbitrary X,Y coordinates are often used in computer-aided drafting (CAD) systems to draw graphic features such as floor plans and electrical circuits.

Determining Need

The discussion now returns to determining a need for a GIS. Based on the definition of GIS, it is obvious that data must have a geographic component in order to be mapped. This is the most important criteria in determining need for a GIS: does the data have a spatial character that is important to the user?

Another significant criterion is the potential of repetitive use of the data. Repetitive use warrants a computer as the analytical engine for operations which would be too time-consuming to do by manual means. (The concept of a GIS in itself does not require the use of a computer.) Repetitive updating of the data file, the examination of multiple scenarios of spatial interaction of several different items that share the same, or nearly the same, space, and the production of multiple copies of a final product without the need to maintain an expensive inventory of maps are some of the reasons to consider the use of a GIS.

Is there a need to understand the spatial relationship of two or more variables that occupy the same space or may be in proximity to each other? A GIS is more than a simple computer mapping tool. Computer mapping assists in the design and production of a single-theme map. There is no attempt to incorporate the results of spatial data analysis in computer mapping. A GIS usually has the capabilities of computer mapping but it is also designed to undertake some degree of exploratory analysis of spatial data.

A GIS is a modeling engine and is constructed to take a series of logical sequences from the user to clearly examine the spatial relationship among variables. Some potential users of GIS technology have the preconceived belief that a GIS is a "black box" engine, ingesting whatever data are available and generating a solution without input from the user. A GIS requires the user to clearly identify the steps of the spatial data analysis. The result can be a means either to evaluate the effectiveness of a spatial data analysis model or to investigate the spatial relationship among variables found at user-defined locations.


GIS, like any other tool, can be effective only if it is the appropriate tool for the appropriate task. A potential user of GIS technology should have a clear understanding of the concepts of geographic information systems and recognize the spatial components of the potential application. Only after accomplishing this should the potential user seek out information about GIS software/hardware systems from prospective vendors. Make sure that the capabilities of a particular GIS will address the tasks identified in the preliminary assessment, and not redefine the problem to accommodate the capabilities of a vendor's GIS product!