Topic summary
Superior good
Extracted from the Wikipedia article Luxury goods.
Confusion with normal goods
In economics, "superior goods" is the gradable antonym of "inferior good". If the quantity of an item demanded increases with income, but not by enough to increase the share of the budget spent on it, then it is only a normal good and is not a superior good. Consumption of all normal goods increases as income increases. For example, if income increases by 50%, then consumption will increase (maybe by only 1%, maybe by 40%, maybe by 70%). A superior good is a normal good for which the proportional consumption increase exceeds the proportional income increase. So, if income increases by 50%, then consumption of a superior good will increase by more than 50% (maybe 51%, maybe 70%).