This also comes up in immigration studies. Say you have two countries A and B. A has an average income of 5, and B has an average income of 20. If a resident of

This also comes up in immigration studies. Say you have two countries A and B. A has an average income of 5, and B has an average income of 20. If a resident of A earning 10 moves to B where he earns 15, the average income of both countries goes down even though total income increases.