I have created a series of thematic maps that join census data to county boundaries. I have then exported these so they are now shape files. I am then trying to carry out an intersection with another polygon layer. The intersection works but when I try to convert the area field to calculate the new area of the smaller polygons, some of the area values go up. This just makes no sense and I have no idea what has gone wrong.
When i joined the two features to make the thematic map, each feature had its own area value, one in miles squared and one in Km squared, it does not matter which field I recalculate after the join I still manage to get area values grater than before.
Has anyone got any ideas about where I am going wrong and what I could try to get it to work?
Any help would be very much appreciated as i have been staring at the screen for hours and i cannot come up with anything.