A product's market price reflects buyers' willingness to purchase and sellers' willingness to produce under stated competitive conditions. Market analysis separates changes in the product's own price from changes in the conditions underlying supply or demand.
Demand describes quantities buyers would purchase at different prices, holding other determinants constant. Supply describes quantities sellers would offer at different prices under the same restriction.
A change in the product's own price causes movement along an unchanged demand or supply curve. A change in another determinant shifts the applicable curve because quantity changes even at the original price.
Demand shifters include the following conditions:
- Wealth: Higher asset wealth can increase demand without increasing current income.
- Related-goods prices: A substitute's price increase can increase demand; a complement's price increase can decrease demand.
- Income: Higher income increases demand for normal goods and decreases demand for inferior goods.
- Preferences: Changes in tastes, perceived quality or convenience alter willingness to purchase.
- Expectations: Anticipated future price increases can bring purchases forward, increasing current demand for storable products.
Common mistakes
- Using a nonbinding controlled price. A $10 ceiling does not force Vale's price to $10; its unchanged $8 equilibrium remains feasible.
- Treating the approximation as exact. The 3% subtraction-based real return exceeds the exact 2.857143% return by approximately 0.142857 percentage points.
- Ignoring currency quotation units. Harbor's exposure change is 200,000 euros x $0.055 per euro = $11,000; 200,000 x 5% = 10,000 does not measure the dollar gain.
Bottom line
- Own-price changes cause movements along curves; changes in other determinants shift supply or demand.
- Binding ceilings create shortages and binding floors create surpluses under the stated competitive model.
- Elasticity calculations require a consistent percentage-change convention; cross-price and income classifications depend on signs.
- Real amounts remove inflation, while future nominal expenses compound inflation; discount rates must match the cash flows' inflation basis.
Exam shortcut
The analysis first identifies the requested output: quantity, revenue, contribution, purchasing power, cash-payment change, market-value change or transaction value. For a market shock, the analysis identifies the changing determinant and affected curve, then tests whether a price control binds before calculating quantities. The calculation uses the stated percentage denominator and exchange-rate quotation units, with basis points converted to decimal yield changes before applying duration.
The full lesson (about 11,920 words, 79 min read) adds 3 worked examples, all 6 common mistakes, a self-check, free in the app.
Learning objectives
- I.B5
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