2.4 - Price Elasticity of Supply
Understanding price elasticity of supply
Price elasticity of supply (PES) measures how responsive the quantity supplied of a good or service is to a change in its price. This concept helps explain how producers react to price incentives and constraints in the market.
PES is important because it shows whether suppliers can easily increase or decrease production in response to price fluctuations. For example, if a price rise leads to a large increase in supply, the supply is highly responsive. Graphs of supply curves can illustrate this: a steeper curve indicates less responsiveness, while a flatter curve shows greater responsiveness.
Calculating price elasticity of supply
To determine PES, you calculate the ratio of the percentage change in quantity supplied to the percentage change in price. This quantifies the sensitivity of supply to price changes.
Formula for price elasticity of supply
Where:
- Percentage change in quantity supplied =
- Percentage change in price =
PES is always positive because price and quantity supplied move in the same direction along a supply curve. You can calculate PES using data from tables or graphs, such as points on a supply curve.
Worked example - Calculating price elasticity of supply
The price of a product increases from $10 to $12, and the quantity supplied rises from 500 units to 700 units. Calculate the PES.
Step 1: Identify the values
- Old price = $10
- New price = $12
- Old quantity supplied = 500 units
- New quantity supplied = 700 units
Step 2: Calculate percentage changes
Step 3: Apply the PES formula
Step 4: Interpretation
A PES of 2 means the quantity supplied is highly responsive to the price change, increasing by twice the percentage of the price rise.
Ranges of price elasticity of supply
The value of PES determines whether supply is elastic, inelastic, or unit elastic. These ranges describe how proportional the change in quantity supplied is to the change in price, with 1 as the benchmark where changes are equal.
Categories of price elasticity of supply:
- Elastic (PES > 1) - Quantity supplied changes by a larger percentage than the price. This occurs when suppliers can easily adjust output, leading to significant supply increases with price rises. On a graph, this appears as a relatively flat supply curve.
- Inelastic (PES < 1) - Quantity supplied changes by a smaller percentage than the price. Suppliers struggle to adjust output quickly, so supply responds minimally to price changes. This shows as a steep supply curve on a graph.
- Unit elastic (PES = 1) - Quantity supplied changes by exactly the same percentage as the price. The response is proportional, often seen in balanced market conditions.
These ranges affect total revenue for suppliers: elastic supply might amplify revenue changes with price adjustments, while inelastic supply limits such impacts.
Factors influencing price elasticity of supply
PES varies based on certain conditions that affect how easily firms can change their production levels.
Key factors affecting PES:
- Availability of alternative inputs - Lower prices or easier access to substitutes allow faster production adjustments, raising PES.
- Time period - In the short run, PES is often lower (more inelastic) due to fixed resources; over the long run, it becomes higher as firms can adapt.
- Spare capacity - Firms with unused resources can increase output quickly, leading to higher PES.
- Storage possibilities - Goods that can be stored easily allow suppliers to respond to price changes by releasing stockpiles, increasing elasticity.
Understanding these factors helps predict how markets respond to price incentives and constraints faced by firms.