1.2.8

Price Determination

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Market Equilibrium

The equilibrium is the point where the demand curve meets the supply curve.

Equilibrium price

Equilibrium price

  • This is the only price where the amount consumers want to buy is equal to the amount producers want to sell.
  • If the market is at equilibrium, there is no reason to move away.
  • Supply and demand (market forces) dictate the equilibrium quantity and price in a free market.
Disequilibrium

Disequilibrium

  • Disequilibrium is when the market is not at a stable price and quantity.
  • If the market is not at equilibrium, economic pressure arises to move the market towards a stable price and quantity.
    • E.g if petrol prices were to rise above their equilibrium level, the market would respond and the quantity demanded would fall.
Excess supply and demand

Excess supply and demand

  • Excess supply and demand occur at disequilibrium.
  • The higher price makes it more profitable for petrol producers, so output expands.
  • The difference between the quantity demanded and quantity supplied is now the excess supply.
  • When quantity demanded exceeds quantity supplied, there is excess demand.
Pressure to reach equilibrium

Pressure to reach equilibrium

  • The market price is unstable when there is excess demand or supply.
  • Excess supply will force producers to cut the price because it is better to sell at a lower price than not at all. Others will follow.
  • Excess demand will signal to producers they can generate more profit by raising the price and will do so.
  • So excess demand and supply can lead to price change.

Equilibrium vs Disequilibrium in a Market

Equilibrium is a state of rest, where price and quantity are stable. In disequilibrium, there is pressure from market forces to reach equilibrium.

Equilibrium

Equilibrium

  • The point of equilibrium is determined by the forces of demand and supply in an economy. These are called market forces. Here, supply is equal to demand.
  • This model of equilibrium assumes perfect competition. It also assumes ceteris paribus (everything else equal), as well as independence between supply and demand.
Disequilibrium

Disequilibrium

  • At disequilibrium, price and quantity are not stable.
  • Market forces will move the economy back to a position of stability at equilibrium over time.

Shifts in Equilibrium

Demand and supply curve shifts affect where an equilibrium is.

Demand curve shifts

Demand curve shifts

  • A shift in the demand curve (but not in the supply curve) will have the following effects:
    • An increase in demand (D->D1) will cause an increase in price. Supply will extend and form a new equilibrium (Q1,P1).
    • A decrease in demand (D->D2)will cause the price to fall. Supply will contract and form a new equilibrium (Q2, P2).
Supply curve shifts

Supply curve shifts

  • A shift in the supply curve (but not in the demand curve) will have the following effects:
    • An increase in supply (S->S1)will cause a decrease in price. Demand will extend and form a new equilibrium (Q1,P1).
    • A decrease in supply (S->S2) will cause an increase in price. Demand will contract and form a new equilibrium (Q2,P2).
Elasticity (slopes of demand and supply curves)

Elasticity (slopes of demand and supply curves)

  • Price elasticity of demand and supply affect how much the equilibrium price and quantity change by.
    • E.g a rightward shift in the demand curve along an elastic supply curve will influence quantity more than price.
    • An inelastic demand curve is steeper than an elastic demand curve.
Jump to other topics
1

Introduction to Markets

2

Market Failure

3

The UK Macroeconomy

4

The UK Economy - Policies

5

Business Behaviour

6

Market Structures

7

A Global Perspective

8

Finance & Inequality

9

Examples of Global Policy

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