The concept of market equilibrium

Market equilibrium is a key idea in economics that describes a balanced state in a market where the plans of buyers and sellers align perfectly. This balance ensures that resources are allocated without any pressure for change, assuming other factors remain constant (ceteris paribus).

Features of market equilibrium

• Equilibrium happens when the quantity supplied exactly matches the quantity demanded at a particular price.
• At this point, the market clears through the price mechanism, meaning all goods produced are sold without leftovers or shortages.
• It occurs where the demand curve (representing consumer plans) intersects with the supply curve (representing supplier plans).
• Total consumer expenditure, which is also the total revenue for sellers, equals price multiplied by quantity.

In the real world, markets are rarely in perfect equilibrium due to constant changes in economic conditions, but they provide a benchmark for understanding market behaviour.

Causes and effects of disequilibrium in markets

Disequilibrium arises when there is an imbalance between supply and demand at the current price, leading to either too much or too little of a good being available. This imbalance creates pressure for the market to change.

Types of disequilibrium

• Excess supply - This occurs when the quantity supplied is greater than the quantity demanded at the given price, often because the price is set too high, resulting in unsold goods.
• Excess demand - This happens when the quantity demanded exceeds the quantity supplied at the given price, typically due to the price being too low, leading to shortages.

These situations are common in actual markets, where factors like sudden changes in consumer preferences or production costs prevent supply and demand from matching exactly.

How markets adjust from disequilibrium to equilibrium

Markets have a natural tendency to move towards equilibrium through adjustments in price and quantity, driven by the motives of consumers seeking value and suppliers aiming to maximise profits. These adjustments help resolve imbalances over time.

The adjustment process in cases of excess supply

• When excess supply exists, suppliers lower prices to attract more buyers.
• Lower prices increase the quantity demanded while reducing the quantity supplied.
• This continues until quantity supplied equals quantity demanded, restoring equilibrium.

The adjustment process in cases of excess demand

• In excess demand situations, suppliers raise prices to manage the shortage.
• Higher prices decrease the quantity demanded while encouraging more supply.
• The process persists until the market clears at a new equilibrium point.

Total consumer expenditure (price × quantity) changes during these adjustments, affecting revenue for suppliers.

Worked example - Adjusting from disequilibrium in the smartphone market

In the smartphone market, at a price of £750, manufacturers supply 15,000 units per week, but consumers demand only 9,000 units. Later, at a price of £450, consumers demand 15,000 units, but manufacturers supply only 9,000 units. Explain the disequilibrium in each case and how the market would adjust.

Step 1: Identify the values for the first scenario

• Price = £750
• Quantity supplied = 15,000 units
• Quantity demanded = 9,000 units

Step 2: Analyse the first disequilibrium

Excess supply = 15,000 - 9,000 = 6,000 units This creates surplus stock, prompting manufacturers to lower prices and reduce production until supply matches demand.

Step 3: Identify the values for the second scenario

• Price = £450
• Quantity supplied = 9,000 units
• Quantity demanded = 15,000 units

Step 4: Analyse the second disequilibrium

Excess demand = 15,000 - 9,000 = 6,000 units This leads to shortages, causing manufacturers to raise prices and increase production until equilibrium is reached.

Factors influencing the speed of market adjustments

Market adjustments do not happen instantly; various factors determine how quickly a market can move from disequilibrium back to equilibrium. These include practical constraints on production and information flow.

Key factors affecting adjustment speed

• Time lags in production - Producers may need time to alter output levels, such as hiring workers or sourcing materials, slowing the response to price changes.
• Price elasticity of supply - Markets with elastic supply adjust faster because producers can easily increase or decrease output; inelastic supply, common in sectors like agriculture, leads to slower adjustments.
• Communication of price information - The speed at which buyers and sellers learn about price changes affects adjustments; modern tools like online comparisons help consumers quickly find better deals across stores or markets.
• Geographic and environmental constraints - Factors such as weather, soil conditions, or location can limit how quickly supply can change, particularly in industries like farming where production cycles are long.
• Market participant motives - Consumers compare prices across channels (e.g., physical stores, online platforms), while suppliers respond to profit opportunities, driving the overall tendency towards equilibrium.

Efficiency and dynamic nature of markets

Markets are constantly evolving, shifting between states of equilibrium and disequilibrium due to changing economic conditions. This dynamic process highlights the role of markets in resource allocation.

Characteristics of market efficiency

• Efficiency at equilibrium - When supply equals demand, markets allocate resources efficiently, with no waste from surpluses or shortages.
• Inefficiency in disequilibrium - Imbalances lead to inefficiencies, such as unsold goods or unmet demand, which waste resources.
• Dynamic market behaviour - Markets are always moving towards equilibrium, influenced by ongoing adjustments, even if they rarely stay balanced for long due to external shocks or internal changes.