Communicating Quantities

For a while now I’ve been trying to figure out precisely why so many people really struggle when it comes to making thematic maps where the purpose is to communicate something about the spatial pattern of numbers. Why do so many pick the wrong map type, select inappropriate classification schemes, use poor colours and so on? Sometimes it’s down to a lack of knowledge and understanding. Sometimes, it’s simply down to the fact that so many people now make maps using software that preselects any number of variables and they neither understand what’s going on or why they would change things. Sometimes it’s down to a lack of time. Sometimes, well...there’s got to be other more fundamental reasons. I then happened across what I found to be an insightful blog post by Santiago Ortiz on Visual.ly (Ortiz, 2012) and think I found the answer that had been staring me in the face for so long. I contacted Ortiz and was granted permission to reprint much of his blog here which I think provides a really valuable insight into why it’s just so fundamentally difficult to map patterns of quantitative data. Ortiz posed the following question at a workshop on interactive data visualisation in 2010: ‘let’s try and find all possible ways to visualize a ludicrously small set of data of two numbers. Afterwards, let’s try and pick the best visualization’. With such a tiny dataset, you would think both exercises could be completed in less than 5 min. Yet, the exercise lasted over 2 h without having actually accomplished either of the two tasks. Not only was the number of possible ways to visualize two values far higher than expected, but also each single visualisation method admitted multiple and interesting variations and opened new questions and discussions. The following is a list of different ways to visualize two numbers. In many cases, the visualisation depends directly on the unit, meaning, interpretation and context of the values. Some of the examples might be seen as variations of the same theme, while others will be perceived as excessively eccentric or even esoteric. The list is, quite probably, not exhaustive! The numbers: 75 and 37