Читать книгу GIS Research Methods - Steven J. Steinberg - Страница 59

The information component of GIS relates to the database aspect of the software. Databases are specialized software programs designed for storing, organizing, and retrieving information. GIS software packages can read or directly interact with data from almost any data management and analysis software. Some data translation may be necessary to facilitate the movement of an existing research database into a GIS software package. Many of the fundamental baseline datasets you might need to answer a question are already available in GIS-ready formats.

In particular, data from the US Census as well as many state- and local-level datasets are available through online sources or via a visit to the appropriate government office. Numerous university sources also provide GIS-ready data, as do a variety of private firms. Many of the data are freely accessible, including a wide range of spatial data from government agencies and other organizations. Additionally, a number of commercial databases are available for purchase. Such databases typically compile specialty data that are in some cases not available through other sources. Commercial data may be updated more frequently and may already be compatible with your GIS software.

The decision whether to use free or commercial data most often comes down to your needs and experience. Esri provides users access to a wide array of both free and commercial datasets designed to operate seamlessly with ArcGIS. Many other third-party providers also sell a wide range of economic, infrastructure, business, and social data types. Commercial data are reviewed for quality and presented in formats that are compatible with popular GIS software applications. Many free sources are similarly prepared, whereas others may require more effort and manipulation to make them compatible with a particular GIS package. Choosing your data source may simply be dependent on your budget. If you do not have the resources to purchase data or to collect your own, new data, you may need to explore free options. Of course, if you use free data, there could be a trade-off in the time it takes to prepare the data for use in your analysis, or the necessary data may simply not be available.

Of course, you can also use your own data, whether collected via survey, interview, observation, or almost any other means. In fact, so long as you intend the data to end up in a computer in digital form, regardless of the particular software involved, it will be accessible to a GIS. In fact, with a little foresight, perhaps through one or two additional questions or notations on the data sheet, you can collect data in a way that facilitates easy incorporation into GIS. These additional data can take the form of either real or conceptual locational information tied to a basemap that you choose (figure 2.6). Thus, the informational aspect of GIS is the easy part because almost everyone working in social sciences is already familiar with the process of collecting and coding data. Most are also familiar with entering data into a computer for analysis.

Figure 2.6 Esri provides a wide range of basemaps through its online map services. Some basemaps may require special licensing. Similar basemaps can be obtained from government agencies and other commercial data providers. Esri.