Why this is mistaken
Demand is the relationship; quantity demanded is one price-specific point on that relationship. Changing the good's own price while holding the relationship fixed changes quantity demanded. Changing a nonprice determinant can shift demand, meaning a different quantity at relevant prices.
Use a two-column repair. In the first, state the old and new own prices and read two points from one labeled curve. In the second, hold a reference price fixed, name the changed nonprice determinant, and compare quantities on two curves. Do not infer the determinant merely from the geometry.
A correct response also separates modeled quantity demanded from actual sales, which depend on supply and market institutions.
Where to watch
When this mistake may appear
- The good's own price changes on a fixed schedule.
- A nonprice determinant changes while the prompt asks about every price.
Check your work
Your work may contain this mistake if:
- Says lower price increased demand when only a movement along the same curve is shown.
- Calls one observed sales quantity the demand curve.
- Names a shift without identifying a nonprice determinant and comparison basis.