Geospatial Modeling and GIS
So far in this book you have seen the way mapping information, even complex and multiple pieces of information, is possible and can be very eﬀective at showing relationships and changes across time and space. Even these maps start to have their limits, however, and the conclusions drawn from them can be suspect, because the social, political, economic, and interpersonal worlds that our data are taken from are complex and multifaceted places. A number of processes are occurring simultaneously in the real world, and just because we can isolate a few of these on a map and show what appears to be a compelling story about, for example, a relationship between crime and alcohol availability, or the lack of a relationship between HIV infection rates and national rivalries, does not mean that we have fully explored the entire realm of possibilities. This is not to say that the maps are not a powerful means with which to support decision making, make policy, and test relationships, at least, that is, in all the examples we have discussed thus far. The realities we need to deal with to be eﬀective at the tasks GIS can help us with call for a greater complexity to the approach we take to gain understanding about how these complexities operate. This section is about how to model the multivariate complexities of the geospatial realities we have already shown you how to construct using GIS. As such this section on spatial modeling is a natural extension of the previous section in which you learned to make complex and multifaceted maps to examine real world problems and relationships.