Change in consumer income:A change in consumer income may bring about a change in the quantity demanded of a good or service. However, the direction of change in quantity demanded will depend on the type of commodity in question. For a normal good, the quantity demanded might increase when consumer income increases and quantity demanded might fall when consumer income falls, ceteris paribus. Therefore, inferior goods are those goods that we consume more when we are worse of financially and less when we are better of. For instance who would want to buy “second hand” goods when he becomes richer? For a necessity, a change in consumer income may not affect quantity demanded.