Why this is mistaken
Supply is the relationship; quantity supplied is one point at a stated price. An own-price change moves along a fixed supply curve. A nonprice change can shift the relationship if sellers would offer a different quantity at relevant prices.
Repair the response by separating the market offer schedule from production, capacity, and accounting inventory. State the reference price, period, seller set, changed determinant, and causal or model basis. Then compare the quantity supplied at that same price before and after the proposed shift.
The correction remains bounded: observed sales can change because demand moved, even when the supply relationship did not.
Where to watch
When this mistake may appear
- The good's own price changes on a fixed schedule.
- Input cost, technology, capacity, expectations, or seller composition changes.
Check your work
Your work may contain this mistake if:
- Says higher price increased supply when only quantity supplied changed.
- Uses ending inventory as the supply curve.
- Names a shift without identifying a nonprice mechanism and controlled comparison.