Читать книгу GIS Research Methods - Steven J. Steinberg - Страница 65

Before initiating an analysis with GIS, it is essential that a GIS represents a model of reality—the computer does not understand reality. Although this may seem obvious, all too often, as people start to consider how they will work with their projects inside a GIS environment, they allow the GIS environment and their data to dictate their approach. Of course, knowledge of the data, the project, the disciplinary expertise, and local knowledge should drive the approach to the study.

Although it can be quite enticing, you should not allow the capabilities of a particular GIS software program or available data to dictate your analytic process. This is especially true when time, money, and personnel available to conduct an analysis are limited. Unfortunately, we cannot offer you a simple solution. Every project requires finding a balance between the real world that you are analyzing and the abstraction that is required to make that reality fit into a GIS. It is important to recognize that there is a distinction between reality as it truly is and reality as represented in the model. When assessing a GIS model or its result, keep yourself firmly planted in the true reality, where your results and decisions affect real people.

Beyond the issues of how the reality fits into the GIS, you will need to consider (as a precursor to this) what reality is for your study. Our discussion of reality isn’t philosophical but rather practical. Defining reality is not always quite as simple as it may seem. For example, if you are doing a survey of household income, where is the breakpoint between economic classes? How might this vary in different geographic regions? Are only dollars and cents relevant? What about bartered services? What about work performed in the home by a member of the household for no pay? As you can see, there are numerous possible components to how income might be assessed and analyzed.

As the analyst who is going to locate, collect, or use these data, how do you define your variables and classes? When looking for archival data, referring to the data dictionary and the metadata may help, if they exist. A data dictionary is a collection of information and details about the data that includes variable names. When collecting your own data, these are the kinds of issues you need to ponder and, in many cases, debate with colleagues, community members, or stakeholders. In short, defining reality is no small task, but it is by far one of the most important.