Desktop.
Courtesy of Esri.
You can also develop or add custom scripts, analytical models, or other tools to supplement the built-in capabilities of ArcGIS. These custom components may be available through online user forums for the specific GIS package or by searching on the Internet. Many of these components are just as good as commercial products, and they are inexpensive or free; however, they may lack formal technical support.
If you are working with others, using a common software platform and version and data standards can save headaches when it comes to data compatibility and analysis. In recent years, geospatial data formats have become much more consistent under the leadership of the Open Geospatial Consortium, which boasts more than four hundred members, including geospatial software companies, government agencies, universities, and other organizations from around the world (http://www.opengeospatial.org).
Open-source GIS
Several open-source GIS software tools are available. Open-source software is free to download from a variety of sites on the Internet, and many of the software programs have supportive user communities happy to help out via e-mail lists. In most cases, you need to compile the program to work with your computer, a process that may require additional open-source components that you download independently. However, open-source software can be an excellent option if you are comfortable working with software with its configurations, and sometimes these tools provide analytical capabilities not readily available with other software.
Physical data model
The final phase of model abstraction is the physical data model. At this point we lay out the software-specific steps—the specific commands or menu options to accomplish the processing necessary for the analysis. Although many GIS programs use similar terminology for particular processes, there are variations.
Here, again, it can be helpful to annotate the flowchart that has been developed to this point. Where lines between data bubbles are located, you can indicate the specific command for your particular software package (figure 2.10). You should note specific names of the data layers used and created at each step. Although this may sound a bit tedious, it can pay off in helping you to keep track of your data at each step along the way. The alternative, trying to keep track of everything in your head when sitting at the computer, is asking for trouble.
Figure 2.10 A portion of the logical data model showing the steps necessary to reduce the full US Census dataset to the appropriate spatial and attribute components necessary for a study of children under age five in the study region. The logical model first indicates a clip, which is a spatial operation to cut out only the required geographic area, much like a cookie cutter. The resulting dataset is then queried to obtain only those records (or attributes) needed in the study.
Even a simple GIS analysis may result in dozens of individual data layers. Developing a flowchart to help you to know what each one is and the software options used to create them can be essential to keeping track of the steps in your analysis. There is nothing worse than accidentally deleting a file you needed. Equally frustrating is when you finally get the solution to your question only to realize you have no idea which steps and software options you used to get there.
Determining project goals
Any person interested in conducting research ultimately begins by determining the main idea, or purpose, of his or her research. For any discipline, the possibilities are endless, especially when it comes to incorporating GIS into the research plan. Many different factors can affect the purpose of your research, such as your personal interests and the interests of the sponsoring organization or agency. Applied research projects may have more than a single purpose, setting out to answer a series of questions or to work toward a solution for specific social problems.
Any time you are going to engage in a research project, you need a clear picture of your goals. A surprising number of people carry out an analysis without asking, What is the purpose of this study? Having a clear project goal is very important because, beyond being the reason for engaging in research in the first place, the goal directly informs the data to locate, collect, and prepare for eventual analysis. A project may have more than one goal—different participants in and funders of the project process may have different goals. If this is the case, it is useful to develop a set of overarching project objectives and a list of needed data prior to beginning the data collection process. One of the most troublesome things that can occur in carrying out an analysis is realizing after the fact that an essential and easy-to-acquire piece of data was not collected as part of the original design. Going back to fill in missing data after the fact, assuming it is possible, can be time consuming, expensive, and, of course, embarrassing. In the GIS realm, you will also need to determine how you will encode the data in a GIS-compatible format that simultaneously works within the GIS and effectively meets the requirements of your study. Chapter 5 addresses these issues in more detail.
Some questions you might ask yourself in developing goals for your study include the following:
If you are able to answer these questions clearly and up front, you will have a much easier time defining the specific goals of the project and thus the data and variables you will require in achieving your objectives.
Guiding questions
The following sections describe four sets of questions you can ask yourself to determine how a GIS could be integrated into your study. The sections include questions about concept, data, location, and analysis.
Questions about concept
The questions in this section focus on the ideological structure of your study. These questions are designed to be asked early on in the research process, usually before you begin implementing your research methodology. When answering these questions, some background research may be necessary; this research should be done before beginning the actual project and going out into the field. You may be able to conduct much of your background research through a literature review and an Internet search or through talks with local experts and others who are familiar with the study site to gain a good understanding of the existing relationships. However, your contact with people