Michigan Radio recently ran a story about a project from Michigan State University’s AgBio Research center that included mapping access to fresh food in Lansing, MI. The map from the project is above (click on the map for a larger image). It’s a beautifully designed map, but in terms of communication, I think this is one for Cartastrophe.
We used it in Intro GIS today as an example of the limitations of dot density mapping, in which dots represent a certain quantity of a phenomenon (in this case, 50 residents) but aren’t necessarily spatially correlated with the actual distribution of the phenomenon. For instance, note the dots representing residents that are placed in the middle of highways. That can be problematic, especially when you’re dealing with a relatively small area in which specific location is exactly what you’re trying to communicate.
Other problems with the MSU map are an unclear legend (what are the items it refers to?) and lack of explanatory text to answer that question and others. For example, why are the areas of accessibility so irregularly shaped? My guess is that they were made using raster analysis of the road network, but without the road network being visualized (and without labels on the roads that are shown), it’s just confusing. A bit of explanatory text would be very helpful.
Furthermore, since transportation is vital to access to food, a map that incorporates statistics on car ownership would be awesome. Witness this map from one of last semester’s Intro GIS students (sorry I can’t insert a picture because it’s a PDF). The design could be improved (this is from a sophomore intro student), but in my opinion this is a much more useful map. The interpolated surface is a much clearer way of communicating proximity to grocery stores, and the incorporation of car-ownership shows that the places where we most need grocery stores to be located are exactly the areas where food is least accessible.
Anyway, I’m very glad for the research going on at MSU, but that map could be greatly improved. I’m also glad that Calvin students are doing similar work at the undergraduate level, and the whole thing has given me an idea for a lab I’m going to try to create around food accessibility.