Price Elasticity of Demand: What Is Elasticity? | Part 1

Main Ideas and Concepts

• Elasticity (in everyday life): describes “stretchiness” (e.g., rubber bands).
• Elasticity (in economics): refers to responsiveness to price changes, specifically price elasticity of demand.
• Law of demand:
  • Price ↑ → quantity demanded ↓
  • Price ↓ → quantity demanded ↑
  • However, the law of demand does not explain how much the quantity changes—elasticity does.

Price Elasticity of Demand (PED)

• Definition: For a given good or service, PED measures how sensitive/responsive consumers are to a change in price.
• How it’s determined: Compare the percent change in quantity demanded to the percent change in price.

Classification Rules

Price Elastic Demand

• Condition: %Δ Quantity demanded > %Δ Price
• Meaning: quantity demanded changes more than price → “stretchy” demand
• Example (from video):
  • Price increases 10%
  • Quantity demanded decreases 20%
  • Result: elastic demand

Price Inelastic Demand

• Condition: %Δ Quantity demanded < %Δ Price
• Meaning: quantity demanded changes less than price → “not stretchy” demand
• Example (from video):
  • Price increases 10%
  • Quantity demanded decreases 5%
  • Result: inelastic demand

Unit Elastic Demand

• Condition: %Δ Quantity demanded = %Δ Price (in opposite direction)
• Meaning: quantity demanded changes by the same proportion as price
• Example (from video):
  • Price increases 20%
  • Quantity demanded decreases 20%
  • Result: unit elastic demand

Pop Quiz Lessons (Answers Included)

1. Black high-top basketball shoes

   • Price: +10%
   • Quantity demanded: -20%
   • Conclusion: Price elastic (quantity change magnitude exceeds price change)

2. Natural gas

   • Price: +10%
   • Quantity demanded: -5%
   • Conclusion: Price inelastic (quantity change magnitude is smaller than price change)

Key Takeaway / Transition

• The video states that athletic shoes are more elastic than natural gas because different goods have different responsiveness to price changes.
• It also says Part 2 will cover four primary factors that influence whether demand is elastic or inelastic.

Speakers / Sources Featured

• No specific named speaker/source is identified in the subtitles (only “Music” cues are present, plus the narrator/teacher voice implicitly).