2.1.6—Movements and shifts in demand

A movement along demand is caused by the good’s own price changing; a shift is caused by a non-price determinant changing.

A movement changes quantity demanded on one curve, while a shift changes demand at every price. Confusing them reverses the diagram and explanation.

Ask “did this good’s price change?” If yes, move along; if not, test income, tastes, related goods or expectations.

A fall in cinema ticket price moves down the curve; a successful film campaign shifts demand right.

A change in demand is not interchangeable with a change in quantity demanded.