Economics – The allocation of resources - Demand | e-Consult

A change in demand refers to a shift of the entire demand curve to the left or right. This is caused by factors other than price, such as changes in consumer income, tastes, expectations, or the prices of related goods (substitutes and complements). A change in quantity demanded refers to a movement *along* the existing demand curve, caused *only* by a change in the price of the good.

If the price of a good decreases, the quantity demanded will increase. This is a movement *along* the existing demand curve. The demand curve itself will not shift. The reason for the increase in quantity demanded is simply that consumers are willing and able to buy more of the good at the lower price.

In summary:

• Change in Demand: Shift of the entire demand curve (due to factors other than price).
• Change in Quantity Demanded: Movement along the existing demand curve (due to a change in price).