Supply and Demand

Supply and demand are the two fundamental forces that set prices and distribute resources in a market economy. Together they determine the equilibrium price — the point where what buyers want to purchase exactly matches what sellers want to sell.

The Law of Demand

Demand: the willingness and ability of buyers to purchase a product or service.

Law of Demand: as price drops, quantity demanded rises. As price rises, quantity demanded falls.

This is an inverse (negative) relationship — price and quantity move in opposite directions. On a standard graph (price on Y-axis, quantity on X-axis), the demand curve slopes downward.

The Law of Supply

Supply: the willingness and ability of producers to offer a good or service for sale.

Law of Supply: as price rises, quantity supplied rises. As price drops, quantity supplied falls.

This is a direct (positive) relationship — price and quantity move in the same direction. The supply curve slopes upward.

Market Equilibrium

The equilibrium price (also called the market price) is the profit-maximizing price at which:

Quantity demanded = Quantity supplied

At equilibrium, the market is in balance. In practice, supply and demand are always shifting, so markets are constantly moving toward equilibrium rather than sitting still at it.

Surpluses and Shortages

Situation	What Happened	Market Response
Surplus	Quantity supplied > Quantity demanded	Producers lower prices to clear inventory
Shortage	Quantity demanded > Quantity supplied	Price rises until supply can meet demand

Both situations are inefficient — firms operating away from equilibrium either lose money (surplus) or miss revenue (shortage).

Consumer and Producer Surplus

Even at equilibrium, participants capture extra value:

• Consumer Surplus: the benefit a buyer gets by paying less than the maximum they would have been willing to pay
• Producer Surplus: the benefit a seller gets by receiving more than the minimum they would have been willing to accept

Together, consumer and producer surplus represent the total value created in a market transaction.

How It Appears Per Course

ADMN 201

Supply and demand are the mechanism by which resources are distributed in Canada’s mixed market economy. Every business decision about pricing and production quantity is ultimately shaped by these forces — whether you’re a lobster fisher in Cape Breton or a Shopify merchant deciding how much inventory to stock.

Cross-Course Connections

EconomicSystems — supply and demand are the allocation mechanism of market economies
DegreesOfCompetition — the degree of competition determines how much power any single firm has to deviate from market price
PrivateEnterprise — profit motive drives both supply decisions and demand behaviour

Key Points for Exam/Study

• Demand: inverse relationship (price ↑ → demand ↓); downward-sloping curve
• Supply: direct relationship (price ↑ → supply ↑); upward-sloping curve
• Equilibrium = where curves intersect; Qd = Qs
• Surplus = supply > demand (quantity too high at this price)
• Shortage = demand > supply (quantity too low at this price)
• Consumer surplus: paid less than max willing to pay; Producer surplus: received more than min willing to accept
• Real markets are always in flux, always moving toward equilibrium

Open Questions

• What specific factors cause the demand or supply curves to shift (covered in later chapters)?

graph TD
    A[Price Increases] -->|Law of Demand - Inverse| B[Quantity Demanded Falls]
    C[Price Decreases] -->|Law of Demand - Inverse| D[Quantity Demanded Rises]
    A -->|Law of Supply - Direct| E[Quantity Supplied Rises]
    C -->|Law of Supply - Direct| F[Quantity Supplied Falls]
    G[Equilibrium Point] -->|Qd = Qs| H[Market Price Set]
    H --> I[Consumer Surplus]
    H --> J[Producer Surplus]
    K[Above Equilibrium] --> L[Surplus: Qs > Qd]
    M[Below Equilibrium] --> N[Shortage: Qd > Qs]