Economist george stigler once wrote that, according to consumer theory, if consumers do not buy less of a commodity when their incomes rise, they will surely buy less when the price of the commodity rises.

On the off chance that purchasers don't purchase to a lesser extent a decent when their earnings rise, the positive qualities being referred to must be a typical decent. For an ordinary decent, the salary and substitution impacts both suggest that the purchaser will purchase less if the value rises.