Factors Affecting Price Elasticity of Supply (PES)

Introduction to Price Elasticity of Supply (PES)

• Price Elasticity of Supply (PES) measures the responsiveness of the quantity supplied of a good or service to a change in its price.

• It is calculated as:

  $$PES = \frac{\% \Delta \text{ in Quantity Supplied}}{\% \Delta \text{ in Price}}$$
  * PES values:
  * Perfectly Elastic: PES = ∞ (horizontal supply curve)
  * Elastic: PES > 1 (quantity supplied is relatively responsive to price changes)
  * Unit Elastic: PES = 1 (percentage change in quantity supplied equals the percentage change in price)
  * Inelastic: PES < 1 (quantity supplied is relatively unresponsive to price changes)
  * Perfectly Inelastic: PES = 0 (vertical supply curve)

KEY TAKEAWAY: PES measures how much the quantity supplied of a good changes when its price changes.

Determinants of Price Elasticity of Supply

1. Spare Capacity

• Definition: Spare capacity refers to the extent to which a firm is operating below its maximum potential output.
• Impact on PES:
  • High Spare Capacity: If firms have a lot of spare capacity (e.g., underutilized equipment, available labor), they can increase production quickly in response to a price increase. This leads to a higher PES (more elastic supply).
  • Low Spare Capacity: If firms are operating near full capacity, it is difficult to increase production quickly without significant investment. This leads to a lower PES (more inelastic supply).
• Example: A factory operating at 50% capacity can easily double its output if demand and prices rise, making its supply more elastic. A factory operating at 95% capacity would struggle to increase output substantially in the short term, making its supply more inelastic.

APPLICATION: Think about the difference between a restaurant with empty tables (high spare capacity) and a fully booked restaurant (low spare capacity).

2. Production Period (Time to Produce)

• Definition: Production period refers to the length of time it takes to produce a good or service.
• Impact on PES:
  • Short Production Period: Goods that can be produced quickly (e.g., a simple manufactured item) tend to have a higher PES. Producers can respond rapidly to price changes.
  • Long Production Period: Goods that take a long time to produce (e.g., agricultural products, complex manufactured goods like airplanes) tend to have a lower PES. It takes time to increase output, even if prices rise.
• Example: The supply of bread is likely more elastic than the supply of wine. Bread can be produced within hours, while wine requires months or years of fermentation and aging.

EXAM TIP: When discussing production period, always relate it back to the ability of the producer to respond quickly to price changes.

3. Durability of Goods

• Definition: Durability refers to how long a good can be stored without significant loss of quality or value.
• Impact on PES:
  • Durable Goods: Durable goods that can be stored easily (e.g., metals, some manufactured goods) tend to have a higher PES. Producers can adjust supply by releasing or withholding stored goods in response to price changes.
  • Perishable Goods: Perishable goods that cannot be stored for long (e.g., fresh fruits, vegetables) tend to have a lower PES. Producers must sell them quickly, regardless of price.
• Example: The supply of gold is more elastic than the supply of ripe tomatoes. Gold can be stored indefinitely, allowing producers to manage supply in response to price fluctuations. Tomatoes must be sold quickly, limiting producers’ ability to respond to price changes.

COMMON MISTAKE: Students often confuse durability with the lifespan of the product in use. Durability in this context refers to storability, not the lifespan of the product once sold.

Summary Table

VCAA FOCUS: VCAA often presents scenarios and asks you to explain how these factors influence the PES of specific goods or services. Make sure you can apply these concepts.