I have a question about heat maps and the correct way to describe the results. I have a dataset of small historic territorial units which vary greatly in size in different parts of a country. I want to demonstrate that certain areas of the country have larger territorial units than others and, rather than produce a map showing all 60000 territorial units as polygons, I think a heat map can achieve what I want.
Using QGIS 2.0 I have created 60,000 points corresponding with the centroid of each territorial unit. I used the QGIS heatmap plugin, setting a radius for 5000m and no advanced features, to create a heatmap. I'm happy with the resulting raster, which I have styled as a conventional blue (low density, 0.00656748) to red (high density, 3.78287).
What I want to know is, when I produce the key for the map, how do I describe it? Is it 'Units per 78.5km²'- the area of a circle of 5km radius? Or 'Count of points in a radius of 5km'? Whilst my main aim is just to show that different parts of the country have different concentrations of territorial units, I want to be able to describe the results correctly. I’m sorry this is a rather basic question.