2.1.5—Demand curve shifts

A demand shift means consumers want a different quantity at every possible price. It is caused by a determinant such as income, tastes, expectations or a related good’s price, not by the good’s own price.

For a normal good, higher income usually shifts demand right; for an inferior good it may shift demand left. Use the good’s classification and the direction of the determinant.

If consumers expect petrol prices to rise next month, current demand may shift right as they buy more now, even though today’s petrol price is unchanged.

A right shift does not mean quantity demanded rises at only one price; it changes the whole relationship.