I have four rasters with cells of 5x5 arc minutes. I transformed the rasters to vectors/ shapefiles. The cells overlap, so I used intersect to combine the layers. It dawns on me that this was not very efficient, and clip might have done a better/ faster job. Nonetheless, it should have yielded the correct results.
However, for some reason I receive most awkward results: For three of the four layers, seemingly every FID is double. When looking at each of these pairs, one sees that the fourth layer displays a zero one row and the correct value for the other row. I know that the value > zero is correct, because this is the value I get when I check the original shapefile.
What has gone wrong and how can I fix it?