I have a shapefile containing three polygons of river basins with different values. I want to know the average values per country. The country thus contains three river basins. When I use join in Arcgis or join by location in QGIS the average value is just the average of the three values, not weighted by the amount of (area) overlap.
example: basin 1 value 1 overlap 1% ; basin 2 value 9 overlap 99% should result in an average value of 8.92 and not 5
the eventual analysis is a global one so speed is critical. I am aware of the option the rasterize and use zonal stats.
