How to Create an Effective Thematic Map



Considering the evolution of automatic mapping programs and the huge amount of available data, the key elements that go into creating thematic maps are presented so that those less familiar with map-making might be able to craft accurate, reliable and illustrative maps.
Here, we used ArcGIS Pro in order to exemplify the process of creating thematic maps presenting correlations between the number of emergency/total 112 calls and the population of Romanian counties. These freely-available data were classified using Natural Brakes, Quantile, Equal Interval, Geometric Interval, Standard Deviation, Defined Interval and Manual Interval, so as to highlight their relevant aspects. The value of the goodness of absolute deviation fit was calculated for each method and each data set. The maps were then created using combined choropleth and proportional symbol methods. The ratio between the total number of 112 calls and the county populations, structured into five classes, has been represented using choropleth method. On the resulting map, emergency calls have been represented with proportional symbols. Furthermore, aspects related to the other map elements were presented all in one place, in order to create a thematic map that would be easy to understand and interpret.
The findings of the present paper could be used by those who want to represent their own data in a very suggestive and reliable manner, without having had any cartographic training beforehand. They could also more easily interpret their datasets and be able to take the necessary steps in their own domains of activity.


classification; emergency calls; symbolization; thematic maps.

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