ABSTRACT
One of the most intuitively reasonable requirements of a measure of concentration of income/wealth within a population is that it should be invariant under scale transformations – the degree of inequality should be the same if incomes are measured in or US$. The situation is rather different if we are comparing inequalities between populations. For instance, suppose we have two populations whose unit income distributions are identical, but with one measured in , the other in US$. Then their ‘within population’ concentration measures will be the same and yet there is clearly a difference ‘between populations’ since if both were expressed in the same units, we would have two populations with different degrees of affluence.
