Separate a shift from a movement
A change in the good's own price moves along a curve. A change in another factor, such as input costs or buyer preferences, can shift a curve. State what stays fixed.
Connect the diagram to the argument
Label price and quantity axes, original curves and equilibrium. Show the affected curve shifting, then compare equilibria. If both curves shift, the direction of price or quantity may depend on their relative changes.
Example
Invented classroom market, not an archive submission or observed price forecast.
- Model
- For notebooks, suppose quantity demanded Qd = 100 - 10P and quantity supplied Qs = 20 + 10P. P is dollars per notebook; quantities are notebooks per week.
- Initial equilibrium
- Set Qd = Qs: 100 - 10P = 20 + 10P. Thus P = $4 and Q = 60 notebooks per week.
- Demand change
- Suppose stronger buyer preferences change demand to Qd = 120 - 10P, with supply unchanged. Solve 120 - 10P = 20 + 10P: P = $5 and Q = 70.
- Interpretation
- Demand shifts right. Price and quantity rise, with a movement along the unchanged supply curve.
Review your draft
Check units and substitute the equilibrium price into both equations. Explain the economic change before describing its mathematical result.
Further reading: OpenStax: changes in equilibrium.
Past supply or demand requests
Real historical request types, described without student text or files.
- Supply or demand coursework request — May 2021
- Supply or demand coursework request — April 2021
- Supply or demand coursework request — April 2021
- Supply or demand coursework request — April 2021
Common questions
Does a higher price shift demand?
A change in the good's own price changes quantity demanded along a given demand curve. It does not itself shift that curve.
Should every analysis include numbers?
Use the information supplied. A qualitative diagram can show directions of change without inventing numerical estimates.