<P> Others are very inconsistent across geographic regions or cultures . The potato, for example, generally conforms to the demand function of an inferior good in the Andean region where the crop originated . People of higher incomes and / or those who have migrated to coastal areas are more likely to prefer other staples such as rice or wheat products as they can afford them . However, in several countries of Asia, such as Bangladesh, potatoes are not an inferior good, but rather a relatively expensive source of calories and a high - prestige food, especially when eaten in the form of "French fries" by urban elites . </P> <P> A special type of inferior good may exist known as the Giffen good, which would disobey the "law of demand". Quite simply, when the price of a Giffen good increases, the demand for that good increases . This would have to be a good that is such a large proportion of a person or market's consumption that the income effect of a price increase would produce, effectively, more demand . The observed demand curve would slope upward, indicating positive elasticity . </P> <P> It was noted by Sir Robert Giffen III that in Ireland during the 19th century there was a rise in the price of potatoes . The poor people were forced to reduce their consumption of meat and expensive items such as eggs . Potatoes still being the cheapest food, in order to compensate they started consuming more even though its price was rising . This phenomenon is often described as "Giffen's Paradox". </P>

As income increases the demand for interior goods