A Giffen good is a low-income, non-luxury product that defies standard economic and consumer demand theory. Demand for Giffen goods rises when the price rises and falls when the price falls.

The quest for the elusive Giffen good has taken economists to the depths of the Irish potato famine, to the poorest parts of rural China and to the cages of lab rats at Texas A&M University.

An inferior good is one whose demand drops when people's incomes rise. When incomes are low or the economy contracts, inferior goods become a more affordable substitute for more expensive goods.

A Veblen good is generally a high-quality, coveted product. This stands in contrast to a Giffen good, which also has an upward-sloping curve but is a non-luxury product with no easily available ...